| On this page we provide you with the mounting evidence of the abortion/breast cancer link. All abstracts were obtained from The National Library of Medicine, an online medical research service. Please visit their site if you would like more information about these particular studies. |
| Studies Which Reported More Than a Twofold Elevation in risk |
(We will be adding a brief explanation for those that do not have an abstract available.)
| Other Studies Which Show Increased Risk |
| Studies showing link between delayed first full term pregnancy and breast cancer |
- Russo et al. Breast Cancer Res Treat 1992;23(3):211-8
Influence of age and parity on the development of the human breast. - MacMahon, B. et al "Age at First Birth and Breast Cancer Risk,"
Bull. Wld Health Org., 1970; (43-209-21) Study reported "It is estimated that women having their first child when aged under 18 years have only about one-third the breast cancer risk of those whose first birth is delayed until the age of 35 or more." Its data also revealed a "suggested increased risk associated with abortion -- contrary to the reduction in risk associated with full-term births."
| Studies for which an abstract is not available: |
- MacMahon, B. et al "Age at First Birth and Breast Cancer Risk," (same as above) Bull. Wld Health Org., 1970; (43-209-21) Study reported "It is estimated that women having their first child when aged under 18 years have only about one-third the breast cancer risk of those whose first birth is delayed until the age of 35 or more." Its data also revealed a "suggested increased risk associated with abortion -- contrary to the reduction in risk associated with full-term births."
- Segi M., et al "An Epidemiological Study on Cancer in Japan," GANN, Vol. 48, Supplement: April, 1957Segi et al (1957) GANN 48 (suppl) : 1-63
| Studies which did not show an increased risk: |
- Sanderson M, Shu X-O, Jin F, Dai Q, Wen W, Hua Y, Gao Y-T, Zheng W. Abortion history and breast cancer risk: results from the Shanghai breast cancer study. Int J Cancer 2001;92:899-905
- Moseson et al. (1993) Int J Epidemiology 22:1000-9
The influence of medical conditions associated with hormones
on the risk of breast cancer. - Melbye et al. N Engl J Med 1997 Jan 9; 336(2):81-5
Induced abortion and the risk of breast cancer - Burany (1979) Jugosl Genekol Opstet 19:237-47 (Serbo-Craot)
- La Vecchia et al. (1993) Int J Cancer 53:215-9
- Zaridze et al (1988) "unpublished" and referenced in Br J Cancer 72:744-51
- Sanderson et al. Amer J Epidemiology, June 1, 2000;151 (11)
Abortion history and breast cancer risk: results from the Shanghai breast cancer study. - Adami et al. (1990) Br J Cancer 62:122-6
Absence of association between reproductive variables and the risk of breast cancer in young women in Sweden and Norway. - Newcomb PA, Mandelson MT. A record-based evaluation of induced abortion and breast cancer risk (United States). Cancer Causes Control 2000; 11:777-81.1
- Goldacre MJ, Kurina LM, Seagroatt V, Yeaates. Abortion and breast cancer: a case-control record linkage study. J Epidem Community Health 2001;55:336-7.
| Other Studies of Interest: (Abstracts are not available for most) |
TITLE: Oral contraceptive use and early abortion as risk factors for breast cancer in young women. AUTHORS: Pike MC; Henderson BE; Casagrande JT; Rosario I; Gray GE
SOURCE: Br J Cancer 1981 Jan;43(1):72-6
CITATION IDS:PMID: 7459241 UI: 81110289
ABSTRACT: A case-control study was conducted in Los Angeles County, California,
of 163 very young breast-cancer cases (all aged 32 or less at diagnosis)
to investigate the role, if any, of oral contraceptives (OC) in the
development of the disease. OC use before first full-term pregnancy
(FFTP) was associated with an elevated risk, which increased with
duration of OC use (relative risk approximately 2.2 at 6 years of use, P
< 0.01). This increased risk could not be explained by other risk factors.
OC use after FFTP was not associated with any change in risk. A
first-trimester abortion before FFTP, whether spontaneous or induced,
was associated with a 2.4-fold increase in breast-cancer risk (P < 0.005). Back to Top
TITLE: Breast cancer risk factors in African-American women: the Howard University Tumor Registry experience. AUTHORS: Laing AE; Demenais FM; Williams R; Kissling G; Chen VW; Bonney GE AUTHOR AFFILIATION: Division of Biostatistics, Howard University Cancer Ctr, Washington, DC 20060.
SOURCE: J Natl Med Assoc 1993 Dec;85(12):931-9
CITATION IDS: PMID: 8126744 UI: 94172652 ABSTRACT:
This retrospective case-control study examines risk factors for breast cancer in African-American women, who recently have shown an increase in the incidence of this malignancy, especially in younger women. Our study involves 503 cases from the Howard University Hospital and 539 controls from the same hospital, seen from 1978 to 1987. Using information culled from medical charts, an analysis of various factors for their effect on breast cancer risk was made. The source of data necessarily meant that some known risk factors were missing. Increases in risk were found for known risk factors such as decreased age at menarche and a family history of breast cancer. No change in risk was observed with single marital status, nulliparity, premenopausal status, or lactation. An increased odds ratio was found for induced abortions, which was significant in women diagnosed after 50 years of age. Spontaneous abortions had a small but significant protective effect in the same subgroup of women. Birth control pill usage conferred a significantly increased risk. It is of note that abortions and oral contraceptive usage, not yet studied in African Americans, have been suggested as possibly contributing to the recent increase in breast cancer in young African-American women. Back to Top
| Other Studies Which Show Increased Risk |
TITLE: Reproductive factors in the etiology of breast cancer.
AUTHORS:Brinton LA; Hoover R; Fraumeni JF Jr
SOURCE:Br J Cancer 1983 Jun;47(6):757-62 ABSTRACT: An interview study of 1,362 breast cancer cases and 1,250 controlsidentified through a multi-centre screening project allowed an evaluation of reproductive determinants of breast cancer. Risk increased linearly with age at first livebirth; women with a birth after Back to Top
TITLE: Breast cancer in relation to the occurrence and time of induced and spontaneous abortion [published erratum appears in Am J Epidemiol 1994 Nov 1;140(9):856]
AUTHORS: Rosenberg L; Palmer JR; Kaufman DW; Strom BL; Schottenfeld D; Shapiro S SOURCE: Am J Epidemiol 1988 May;127(5):981-9 ABSTRACT:The authors evaluated whether an induced or spontaneous abortion during the first six months of gestation, particularly if it occurs before the first term pregnancy, increases the risk of breast cancer. Data from a case-control study of women under 70 years of age were used: 3,200 cases of breast cancer were compared with 4,844 controls with nonmalignant nongynecologic conditions. Among both nulliparous and parous women, the risk of breast cancer was not related to the number of induced or spontaneous abortions. After allowance for all identified potential confounding factors, the estimated relative risk for nulliparous women with an induced abortion relative to those who had never been pregnant was 1.3 (95% confidence interval (CI) 0.8-2.2), and for spontaneous abortion, the corresponding estimate was 0.9 (95% CI 0.5-1.5). Among parous women, the estimated relative risks were 1.2 (95% CI 0.9-1.6) for an induced abortion and 0.9 (95% CI 0.8-1.0) for a spontaneous abortion, relative to never having had an abortion of any type. The time of the abortion had little effect: The relative risk estimates were 0.9 (95% CI 0.5-1.4) for induced abortion before the first term birth, 1.4 (95% CI 1.0-1.9) for induced abortion first occurring after the first term birth, 0.9 (95% CI 0.7-1.2) for spontaneous abortion before the first term birth, and 0.9 (95% CI 0.7-1.0) for spontaneous abortion first occurring after the first term birth. Similar results were evident for women under age 40, among whom the frequency of induced abortion was relatively high. These data suggest that the risk of breast cancer is not materially affected by abortion, regardless of whether it occurs before or after the first term birth. Back to Top TITLE: Adolescent reproductive events and subsequent breast cancer risk.
AUTHORS: Marcus PM; Baird DD; Millikan RC; Moorman PG; Qaqish B; Newman B AUTHOR AFFILIATION: Division of Cancer Prevention, National Cancer Institute, Bethesda, MD 20892-7354, USA. pm145q@nih.gov
SOURCE: Am J Public Health 1999 Aug;89(8):1244-7
CITATION IDS: PMID: 10432916 UI: 99361582 NOTE FROM THE COALITION: The latest tactic for the abortion-breast cancer scientists who are trying to politicize their findings is to write misleading abstracts and to publish studies that are too small to implicate induced abortion as a risk factor for breast cancer. While it does not say so, the Marcus study is the twelfth American study to implicate induced abortion as a risk factor for breast cancer, showing a risk increase of 20%. It is the thirteenth U.S. study to publish data on the abortion-breast cancer link. See Dr. Joel Brind's Fall, 1999 issue of the Abortion-Breast Cancer Quarterly Update for his commentary. ("New NCI Study Finds -- But Covers Up -- ABC Link in North Carolina Women," p. 3).
ABSTRACT:
OBJECTIVES: This study investigated the relationship between reproductive events during adolescence and subsequent breast cancer risk. METHODS: Logistic regression models used self-reported data from 862 case patients and 790 controls in the Carolina Breast Cancer Study. RESULTS: Miscarriage, induced abortion, and full-term pregnancy before 20 years of age were not associated with breast cancer. Among premenopausal women, breast-feeding before 20 years of age was inversely associated with disease. Oral contraceptive use before 18 years of age was positively associated with disease risk among African American women only. CONCLUSIONS: Pregnancy during adolescence does not appear to influence breast cancer risk, but breast-feeding may. A possible increased breast cancer risk among African American women who used oral contraceptives as adolescents warrants further study. Back to Top
TITLE: Induced and spontaneous abortion in relation to risk of breast cancer (United States).
AUTHORS: Palmer JR; Rosenberg L; Rao RS; Zauber A; Strom BL; Warshauer ME; Stolley PD; Shapiro S
SOURCE:Cancer Causes Control 1997 Nov;8(6):841-9
ABSTRACT:
The relation of induced and spontaneous abortion to the risk of breast cancer is evaluated in a hospital-based case-control interview study conducted in three cities in the United States from 1985 through 1995. Cases were 1,803 women aged 25 to 64 years with newly diagnosed invasive breast cancer; controls were 4,182 women of the same ages admitted for conditions unrelated to reproductive factors. Other breast cancer risk-factors were controlled through multiple logistic regression. The reference for all analyses was women who had never had an abortion, either induced or spontaneous. Among parous women, the relative risk (RR) estimate was 1.1 (95 percent confidence interval [CI] = 0.9-1.5) for induced abortion overall, 1.0 (CI = 0.7-1.4) for abortion before the first birth, and 1.3 (CI = 1.0-1.8) for abortion after at least one birth. Among nulliparous women, the relative risk estimate for induced abortion was 1.3 (CI = 0.9-1.9). There was no trend of increased risk with number of abortions, nor was there consistent evidence of an increased risk in any particular subgroup. Spontaneous abortion was not associated with increased risk of breast cancer, either among nulliparous women or among parous women. These findings provide little support for the hypothesis that induced abortion increases breast cancer risk overall or in particular subgroups. Back to Top TITLE: Induced abortion and breast cancer risk. AUTHORS: Lazovich D; Thompson JA; Mink PJ; Sellers TA; Anderson KE
AUTHOR AFFILIATION: Division of Epidemiology, School of Public Health, University of Minnesota, Minneapolis 55454-1015, USA.
SOURCE:Epidemiology 2000 Jan;11(1):76-80
CITATION IDS: PMID: 10615848 UI: 20081594 NOTE FROM THE COALITION: This is also a very small study. The low statistical power of the study makes it impossible to determine significance. Lazovich reported an increased risk of breast cancer of 10% for postmenopausal women with histories of having had induced abortions. This study is the fourteenth American study, and the thirteenth to report an increased risk. It is the twenty-seventh of thirty-four worldwide studies to link abortion with breast cancer. ABSTRACT:
Results from case-control studies suggest that induced abortion may be associated with a small increase in risk of breast cancer. While risk estimates from cohort studies have generally not observed such an association, these studies have had limited information regarding abortion and possible confounding variables. Therefore, we conducted a study among a cohort of post-menopausal women from whom detailed information regarding pregnancy outcomes as well as risk factors for breast cancer had been collected. The study sample included 37,247 Iowa Women's Health Study participants, 55-64 years of age at baseline
in 1986, who reported no history of breast, or other, cancer (except non-melanoma skin cancer), and for whom information regarding pregnancy outcomes (that is, live birth, stillbirth, spontaneous abortion, ectopic pregnancy or induced abortion) was available. We used linkage with records of the State Health Registry of Iowa, part of the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) program, to estimate the incidence of breast cancer among cohort
members through 1995. We calculated age-adjusted relative risks and
95% confidence intervals using Cox proportional hazards regression. Only 653 women (1.8%) reported an induced abortion. The age-adjusted relative risk of breast cancer among women with prior induced abortion compared with those without was 1.1 (95% CI = 0.8-1.6). Relative risks were higher among women whose age at first abortion was less than 20 or at least 30 years, for those whose abortion took place after their first birth or who never gave birth, and for those with early termination (0-2 months). These estimates varied from 1.3-1.7, but the confidence intervals around each were wide. Since most women in this cohort were beyond their reproductive years when abortion became legal in 1973,
the low prevalence of induced abortion argues for a cautious
interpretation. Back to Top
TITLE: Risk of breast cancer among white women following induced abortion. AUTHORS: Daling JR; Brinton LA; Voigt LF; Weiss NS; Coates RJ; Malone KE; Schoenberg JB; Gammon M
AUTHOR AFFILIATION: Division of Public Health Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98104, USA.
SOURCE: Am J Epidemiol 1996 Aug 15;144(4):373-80
CITATION IDS: PMID: 8712194 UI: 96316782 ABSTRACT:
Some studies (but not all) have suggested that there may be an increase in the risk of breast cancer associated with a prior induced abortion. The risk, if present, may vary according to the duration of the pregnancy in which the abortion occurred, or to a woman's age or parity at that time. The authors conducted a case-control study of breast cancer in white women under age 45 years to address the question of breast cancer risk in relation to induced abortion, with the intention of identifying subgroups of women who might be at particularly increased risk. White women who were diagnosed with breast cancer (n = 1,302) from May 1, 1990, through December 31, 1992, in three geographic regions of the United States (Atlanta, Georgia; Seattle/Puget Sound, Washington; and five counties in central New Jersey) were interviewed about their reproductive histories, including the occurrence of induced abortion. Similar information was obtained from control women identified through random digit dialing. Logistic regression analysis was used to estimate the relative risk of breast cancer associated with a history of induced abortion, controlling for the potentially confounding influence of other breast cancer risk factors. Among women who had been pregnant at least once, the risk of breast cancer in those with a prior induced abortion was 20% higher than that in women with no history of abortion (95% confidence interval 1.0-1.5). This small increase in risk varied little according to number of abortions or a woman's current age. The association was present primarily among nulliparous women whose abortions occurred prior to 9 weeks' gestation (estimated relative risk = 2.0, 95% confidence interval 1.2-3.3). There was no excess risk of breast cancer associated with induced abortion among parous women. These data support the hypothesis that there may be a small increase in the risk of breast cancer related to a history of induced abortion among young women of reproductive age. However, the data from this study and others do not permit a causal interpretation at this time; neither do the collective results of the studies suggest that there is a subgroup of women in whom the relative risk associated with induced abortion is unusually high. Back to Top TITLE: Risk of breast cancer among young women: relationship to induced abortion. (see comment) AUTHORS: Daling JR; Malone KE; Voigt LF; White E; Weiss NS
AUTHOR AFFILIATION: Division of Public Health Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98104.
SOURCE: J Natl Cancer Inst 1994 Nov 2;86(21):1584-92
CITATION IDS: PMID: 7932822 UI: 95018337
COMMENT: Comment in: J Natl Cancer Inst 1994 Nov 2;86(21):1569-70 ABSTRACT:
BACKGROUND: Certain events of reproductive life, especially completed pregnancies, have been found to influence a woman's risk of breast cancer. Prior studies of the relationship between breast cancer and a history of incomplete pregnancies have provided inconsistent results. Most of these studies included women beyond the early part of their reproductive years at the time induced abortion became legal in the United States. PURPOSE: We conducted a case-control study of breast cancer in young women born recently enough so that some or most of their reproductive years were after the legalization of induced abortion to determine if certain aspects of a woman's experience with abortion might be associated with risk of breast cancer. METHODS: Female residents of three counties in western Washington State, who were diagnosed with breast cancer (n = 845) from January 1983 through April 1990, and who were born after 1944, were interviewed in detail about their reproductive histories, including the occurrence of induced abortion. Case patients were obtained through our population-based tumor registry (part of the Surveillance, Epidemiology, and End Results Program of the National Cancer Institute). Similar information was obtained from 961 control women identified through random digit dialing within these same counties. Logistic regression analysis was used to estimate odds ratios and confidence intervals (CIs). RESULTS: Among women who had been pregnant at least once, the risk of breast cancer in those who had experienced an induced abortion was 50% higher than among other women (95% CI = 1.2-1.9). While this increased risk did not vary by the number of induced abortions or by the history of a completed pregnancy, it did vary according to the age at which the abortion occurred and the duration of that pregnancy. Highest risks were observed when the abortion was done at ages younger than 18 years--particularly if it took place after 8 weeks' gestation--or at 30 years of age or older. No increased risk of breast cancer was associated with a spontaneous abortion (RR = 0.9; 95% CI = 0.7-1.2). CONCLUSION: Our data support the hypothesis that an induced abortion can adversely influence a woman's subsequent risk of breast cancer. However, the results across all epidemiologic studies of this premise are inconsistent--both overall and within specific subgroups. The risk of breast cancer should be reexamined in future studies of women who have had legal abortion available to them throughout the majority of their reproductive years, with particular attention to the potential influence of induced abortion early in life. Back to Top TITLE: Breast cancer among young U.S. women in relation to oral contraceptive use.
AUTHORS: White E; Malone KE; Weiss NS; Daling JR
SOURCE: J Natl Cancer Inst 1994 Apr 6;86(7):505-14 ABSTRACT:
BACKGROUND: While most studies have found no association between oral contraceptive use and breast cancer, several studies of younger women have reported an association with long-term oral contraceptive use. PURPOSE. We studied the relationship of patterns of oral contraceptive use to breast cancer risk among younger women. These women have had oral contraceptives available their entire reproductive lives and are now entering the breast cancer-prone years. METHODS: A population-based, case-control study of breast cancer was conducted in three counties in western Washington State among women born in 1945 or later, ages 21-45. Case patients were 747 women with breast cancer diagnosed in 1983-1990 and identified through the Seattle-Puget Sound Surveillance, Epidemiology, and End Results cancer registry. Control subjects were 961 women identified by random-digit telephone dialing. Subjects were interviewed in person, using pictures of brands of oral contraceptives and calendars of life events as recall aids. RESULTS: There was no increased incidence of breast cancer associated with ever having used oral contraceptives. Because only 8% of this cohort had never used oral contraceptives, short-term users (< 1 year) were combined with never users as the reference group for further analyses. A small increased risk of breast cancer was associated with long duration of oral contraceptive use (odds ratio for > or =
10 years = 1.3; 95% confidence interval [CI] = 0.9-1.9; P for trend = .03), particularly among women aged 35 years or younger (odds ratio for > or = 10 years = 1.7; 95% CI = 0.9-3.1). Breast cancer was also modestly related to oral contraceptive use early in reproductive life (odds ratio for use within 5 years of menarche = 1.3; 95% CI = 1.0-1.8; P for trend = .04) and to use of high-progestin-potency oral contraceptives for at least 1 year (odds ratio = 1.5; 95% CI = 1.1-2.1). These associations were adjusted for age, age at menarche, term pregnancy, induced abortion, and family history of breast cancer. The associations were not further confounded by case-control differences in education, religion, breast feeding of offspring, or infertility; in oral contraceptive contraindications, indications, or complications; or in measures of breast cancer detection such as mammography or breast biopsy. CONCLUSIONS: Long-term oral contraceptive use among young women or use beginning near menarche may be associated with a small excess breast cancer risk, possibly due to susceptibility to genetic damage in breast epithelial cells at ages of high breast cell proliferative activity. IMPLICATIONS: Future studies should investigate whether the patterns of risk we reported are present as this cohort ages. Back to Top TITLE: Pregnancy termination in relation to risk of breast cancer [seecomments]
AUTHORS: Newcomb PA; Storer BE; Longnecker MP; Mittendorf R; Greenberg ER; Willett WC
SOURCE: JAMA 1996 Jan 24-31;275(4):283-7 ABSTRACT:
OBJECTIVE--To evaluate the association between pregnancy terminations and risk of breast cancer. DESIGN AND SETTING--Population-based case-control study in Wisconsin, Massachusetts, Maine, and New Hampshire. STUDY PARTICIPANTS--Cases were women younger than 75 years with a new diagnosis of breast cancer (n = 6888), identified from statewide tumor registries. Controls younger than 65 years (n = 9529) were randomly selected from lists of licensed drivers, or for older subjects, from lists of Medicare beneficiaries. EXPOSURES AND OUTCOMES--Breast cancer risk in relation to spontaneous or induced abortions. RESULTS--After adjustment for parity, age at first birth, and other risk factors, pregnancy termination (induced or spontaneous) was associated with a relative risk (RR) of breast cancer of 1.12 (95% confidence interval [CI], 1.04 to 1.21), compared with the risk among women who had never had a termination. Induced terminations were associated with a RR of 1.23 (95% CI, 1.00 to 1.51), which was somewhat greater than the risk associated with spontaneous terminations (RR, 1.11; 95% CI, 1.02 to 1.20). The association with induced abortions was stronger for those performed before legalization of abortion in 1973 (RR, 1.35; 95% CI, 1.01 to 1.80) than after this time (RR, 1.12; 95% CI, 0.84 to 1.49), suggesting a bias in reporting this sensitive procedure. CONCLUSIONS--A weak positive association was observed between abortion--whether induced or spontaneous--and risk of breast cancer. The increase in risk of breast cancer was somewhat greater among women with a history of induced terminations. However, this association may be due to reporting bias and was not significantly different than the slight risk for spontaneous terminations. Back to Top TITLE: Early abortion and breast cancer risk among women under age 40. AUTHORS: Howe HL; Senie RT; Bzduch H; Herzfeld P
AUTHOR AFFILIATION: Division of Epidemiology, New York State Department of Health.
SOURCE: Int J Epidemiol 1989 Jun;18(2):300-4
CITATION IDS:
PMID: 2767842 UI: 89358398 ABSTRACT:
In New York State, incidence of cancer and fetal death are reportable health events mandated by state law. These data enabled a population-based record linkage study of the effect of early pregnancy termination on breast cancer risk to be conducted. In upstate New York 1451 cases under age 40 were reported to the Cancer Registry during 1976-1980. Cases were matched with 1451 population controls by year of birth and by residence using zip codes. All names including those changed by marriage were matched with the reports of fetal deaths occurring between 1971 and 1980. Matched pairs analyses revealed an excess of early pregnancy terminations among cases in all categories. Odds ratios (OR) were significantly elevated among those with an induced abortion (OR = 1.9) and a spontaneous abortion (OR = 1.5). Elevated risks were also noted for consecutive abortion events without intervening livebirths. Back to Top TITLE: A population-based case-control study of diet and breast cancer in Australia. AUTHORS: Rohan TE; McMichael AJ; Baghurst PA
AUTHOR AFFILIATION: CSIRO Division of Human Nutrition, Adelaide, Australia.
SOURCE: Am J Epidemiol 1988 Sep;128(3):478-89
CITATION IDS: PMID: 3414656 UI: 88324377 NOTE FROM THE COALITION: This 1988 study, which was conducted on Australian women, revealed the reluctance of researchers to publish data showing the association between induced abortion and breast cancer. Abortion-breast cancer data obtained by the Rohan researchers were not published with the rest of the data in the American Journal of Epidemiology and were withheld for seven years, in spite of the fact that induced abortion was found to be the strongest risk factor found. The data were not published until Nadine Andrieu's 1995 meta-analysis of six studies examining the synergistic effect between family history and induced abortion came out in France. This was the first time that the abortion-breast cancer data in the Rohan study was ever published, and it revealed a 160% increased risk of breast cancer among Australian women who had had induced abortion. It was the only variable in the Rohan study which was statistically significant, even surpassing family history in increased risk. Spontaneous abortion was not linked with breast cancer.
ABSTRACT:
The relation between diet and breast cancer was examined in a
population-based case-control study conducted in Adelaide, South Australia,
involving 451 case-control pairs aged 20-74 years. Cases were identified
through the state cancer registry between April 1982 and July 1984; for
each case, one age-matched control was selected from the electoral register.
Dietary intake was measured by self-administered quantitative food
frequency questionnaires. There was little variation in risk across levels of
daily intake of energy, protein, and total fat; for energy, the relative risk of
breast cancer at the uppermost fifth of intake, relative to a risk of unity for
the lowest fifth, was 1.22 (95% confidence interval (CI) 0.80-1.86); for
protein, the corresponding relative risk was 1.09 (95% CI 0.72-1.64), and for
total fat, the relative risk was 0.90 (95% CI 0.59-1.38). Variation in risk in
association with sugar and starch intake was also insubstantial, while for
fiber, there was a nonuniform reduction in risk at the three uppermost fifths
of intake. Risk varied little with level of retinol intake, but it decreased with
increasing intake of beta-carotene, a trend that was statistically significant;
the relative risk of breast cancer at the uppermost fifth of beta-carotene
intake was 0.76 (95% CI 0.50-1.18). Multivariate adjustment for the effects
of potentially confounding variables did not alter these patterns. The study
does not support a role for dietary fat in the etiology of breast cancer. Back to Top TITLE: Familial risk, abortion and their interactive effect on the risk of breast cancer--a combined analysis of six case-control studies. AUTHORS: Andrieu N; Duffy SW; Rohan TE; Le MG; Luporsi E; Gerber M; Renaud R; Zaridze DG; Lifanova Y; Day NE
AUTHOR AFFILIATION: Unite INSERM 351, Institut Gustave Roussy, Villejuif, France.
SOURCE: Br J Cancer 1995 Sep;72(3):744-51
CITATION IDS:PMID: 7669588 UI: 95399199 ABSTRACT:
In a previous study in France, we reported that the relative risk of breast
cancer associated with a family history of breast cancer was higher in those
subjects with a history of abortions. The present study was undertaken to
check the existence of this interaction in other studies and to investigate
whether the interaction is modified by the time at which abortions occur.
Data were obtained from six case-control studies in France, Australia and
Russia, with information on family history of breast cancer and abortion for
2693 breast cancer cases and 3493 controls. The interaction effect was
estimated in each study separately, then combined using a multivariate
weighted average. The relative risk conferred by a family history of breast
cancer increased with the number of abortions (1.8 for no abortion, 1.9 for
one abortion, 2.8 for two or more). There was a significant interaction
between total number of abortions and family history (P = 0.04), but this was
no longer significant when adjusted for other risk factors. The familial risk
was highest for those who had had an abortion before first childbirth (1.9 for
abortion after first childbirth, 2.7 for abortion before first childbirth). The
adjusted risk associated with family history was significantly higher in those
with an abortion before first childbirth (P = 0.04). Our findings suggest a
synergism between familial factors and abortion. The interaction was not
substantially modified by the type of abortion (spontaneous or induced) but
was modified by the time at which it occurred in relation to first childbirth.
This suggests an effect of abortion itself rather than predisposition to
abortion. Further studies of breast cancer cases, particularly among BRCA1
gene carriers and their families, could improve our understanding of this
effect. Back to Top TITLE: Occurrence of breast cancer in relation to diet and reproductive history: a case-control study in Fukuoka, Japan. AUTHORS: Hirohata et al. (1985) Natl Cancer Inst Monogr 69:187-90 ABSTRACT: An epidemiologic study on breast cancer in relation to diet and reproductive history was conducted with 3 populations at different levels of risk for the disease: Japanese in Fukuoka, Japan (low risk), Japanese in Hawaii (intermediate risk), and Caucasians in Hawaii (high risk). This report describes the Fukuoka portion of the study. We interviewed 212 patients with histologically confirmed breast cancer and an equal number each of hospital and neighborhood controls to determine risk factors for the disease. The results indicated that "overnutrition" (a high-fat and high-animal protein diet) was not statistically associated with the disease. As noted in previous studies, age at the first birth was positively related to the disease; those women who gave birth to their first child when they were 35 or more years of age showed a relative risk of 5.0 compared with those giving birth at less than 20 years of age. A past history of both natural abortion and of benign breast disease were significantly associated with the disease. On the whole, the results obtained from this Fukuoka portion of study were in good agreement with those from the Hawaii study during which Japanese and Caucasians in Hawaii were investigated. Back to Top TITLE: Risk of breast cancer in relation to reproductive factors in Denmark.
AUTHORS: Ewertz M; Duffy SW
SOURCE: Br J Cancer 1988 Jul;58(1):99-104
ABSTRACT: The effect of reproductive factors on breast cancer risk was evaluated in a population-based case-control study, including 1,486 breast cancer cases diagnosed over a one-year period in Denmark. They were identified from the files of the nationwide trial of the Danish Breast Cancer Co-operative group and the Danish Cancer Registry. The control group was an age-stratified random sample of 1,336 women from the general population. Data on risk factors were collected by self-administered (mailed) questionnaires. Significantly increased relative risks (RR) were associated with never being pregnant (RR = 1.47), an early terminated first pregnancy (RR = 1.43), and having a natural menopause after the age of 54 (RR = 1.67). Trends of decreasing risk were observed by increasing parity and age at menarche. These findings were independent of age at first full-term pregnancy which overall was not related to breast cancer risk, though a weak association appeared in women less than 50 years at diagnosis. The study confirmed that pregnancies must continue to term to offer protection against breast cancer.
Back to Top TITLE: Abortion and the risk of breast cancer: a case-control study in Greece
AUTHORS: Lipworth L; Katsouyanni K; Ekbom A; Michels KB; Trichopoulos D
SOURCE: Int J Cancer 1995 Apr 10;61(2):181-4 ABSTRACT: We have examined the association between induced or spontaneous abortion and breast cancer risk in Greece. In a hospital-based case-control study in Athens, 820 patients with confirmed breast cancer were compared with 795 orthopedic patient controls and 753 healthy visitor controls, matched to cases by age and interviewer. Logistic regression was used to analyze the data, controlling for demographic, reproductive and nutritional variables. Odds ratio (OR) patterns were similar for the 2 control series, which were therefore combined to increase precision of the estimates. The risk for breast cancer was not increased for women who had a history of abortion, compared to nulliparous women with no history of abortion. Thus ORs and 95% confidence intervals were for nulliparous women with spontaneous abortion, 1.17 (0.64-2.13); for nulliparous women with induced abortion, 0.98 (0.56-1.73); for parous women with no abortion, 0.56 (0.31-1.01); for parous women with spontaneous abortion, 0.61 (0.33-1.14) and for parous women with induced abortion, 0.99 (0.56-1.74). When the analysis was restricted to parous women, using parous women with no history of abortion as the baseline, ORs and 95% confidence intervals were for induced abortion before first full-term pregnancy, 2.06 (1.45-2.90); for induced abortion after first full-term pregnancy, 1.59 (1.24-2.04) and for spontaneous abortion, 1.10 (0.82-1.40). Our findings suggest that an interrupted pregnancy does not impart the long-term protective effect of a full-term pregnancy attributable to terminal differentiation. Back to Top TITLE: Induced abortion and risk for breast cancer: reporting (recall) bias in a Dutch case-control study
AUTHORS: Rookus MA; van Leeuwen FE
SOURCE:J Natl Cancer Inst 1996 Dec 4;88(23):1759-64 COMMENT:Comment in: J Natl Cancer Inst 1996 Dec 4;88(23):1698-700
Comment in: J Natl Cancer Inst 1997 Apr 16;89(8):588-90 ABSTRACT:BACKGROUND: In general, no association has been found between spontaneous abortion (naturally occurring termination of a pregnancy) and the risk for breast cancer. With respect to induced abortion (termination of a pregnancy by artificial means), the results have been more inconclusive. A positive association was found in five studies, no association was found in six studies, and a negative association was found in the only cohort study. It is thought that part of the inconsistency of the reported results may be attributable to reporting (recall) bias, since all but two studies on induced abortion used the case-control design and were based only on information obtained from study subjects. In comparison with breast cancer case patients, healthy control subjects may be more reluctant to report on a controversial, emotionally charged subject such as induced abortion. Thus, differential underreporting may be a cause of spurious associations in case-control studies. PURPOSE: Our goal was threefold: 1) to evaluate the relationship between a history of induced or spontaneous abortion and the risk for breast cancer in a Dutch population-based, case-control study; 2) to examine reporting bias by comparing risks between two geographic areas (i.e., western regions and southeastern regions in The Netherlands that differ in prevalence of and attitudes toward induced abortion); and 3) to compare reporting bias in data on induced abortion with reporting bias in data on oral contraceptive use. METHODS: Data analyzed in this study were obtained from 918 women (20-54 years of age at diagnosis) who were diagnosed with invasive breast cancer during the period from 1986 through 1989 and had been initially enrolled in a population-based, case-control study investigating oral contraceptive use and breast cancer risk. The women resided in one of four geographic areas that were covered by Regional Cancer Registries: two western regions (Amsterdam and West) and two southeastern regions (East and Eindhoven). Each case patient was pair-matched, on the basis of age (within 1 year) and region, with a control subject who was randomly selected from municipal registries that fully covered the Dutch population. Both the case patients and the control subjects were interviewed at home by the same trained interviewer, who used a structured questionnaire. Reporting bias was examined indirectly by comparing risks between the western and the southeastern regions of the country, which differ in the prevalence of and attitude toward induced abortion. Multivariate conditional logistic regression methods for individually matched case-control studies were used to estimate relative risks (RRs). Reported P values are two-sided. RESULTS AND CONCLUSION: Among parous women, a history of induced abortion was associated with a 90% increased risk for breast cancer (adjusted RR = 1.9; 95% confidence interval [CI] = 1.1-3.2). Among nulliparous women, no association between induced abortion and breast cancer was found. Neither among parous women nor among nulliparous women was a history of spontaneous abortion related to the risk for breast cancer. The association between induced abortion and breast cancer was stronger in the southeastern regions of the country, which have a predominantly Roman Catholic population, than in the western regions (adjusted RR = 14.6 [95% CI = 1.8-120.0] versus adjusted RR = 1.3 [95% CI = 0.7-2.6], respectively; test of difference between regions, P = .017), suggesting reporting bias. Support for reporting bias as an explanation for the regional differences was also found in data supplied by both study subjects and their physicians on the use of oral contraceptives. In comparison with physicians, control subjects in the southeastern regions underreported the duration of their oral contraceptive use by 6.3 months more than control subjects in the western regions (P = .007)... Back to Top TITLE: The role of reproductive and menstrual factors in cancer of the breast before and after menopause [see comments]
AUTHORS:Talamini R; Franceschi S; La Vecchia C; Negri E; Borsa L; Montella
M; Falcini F; Conti E; Rossi C
SOURCE: Eur J Cancer 1996 Feb;32A(2):303-10
COMMENT:Comment in: Eur J Cancer 1996 Nov;32A(12):2181-2 ABSTRACT:The aim of the study was to elucidate the role of reproductive and menstrual factors in the aetiology of breast cancer, overall and by menopausal status. A cooperative case-control study was conducted between 1991 and 1994 in six different Italian areas (including three from the centre and the south). The study included 2569 histologically confirmed incident cases of breast cancer (median age 55 years, range 23-78 years) and 2588 control women (median age 56 years, range 20-79 years) admitted to the same hospitals for a variety of acute conditions unrelated to the hypotheses in study. A trend of increasing risk with increasing age at menopause (odds ratio (OR) for age at menopause > or = 53 versus < 45 years = 1.8; 95% confidence interval (CI) = 1.4-2.2). High parity reduced cancer risk (OR for > or = 4 versus 1 birth = 0.7; 95% CI = 0.5-0.9). Overall, nulliparous women showed a 20% lower risk than uniparous ones (OR = 0.8; 95% CI = 0.7-1.0). Late age at first birth (or pregnancy) had an independent adverse effect (OR for first birth at > or = 32 versus < 20 years = 1.7; 95% CI = 1.3-2.1) both before and after menopause. An approximately 2-fold elevation of breast cancer risk was evident up to 10 years after the last birth. No trend in risk was evident for induced abortions (OR = 1.2 for 1 and 1.1 for > or = 2 induced abortions versus 0). Other examined menstrual and reproductive characteristics did not seem important. Multiparity, early age at first birth and early age at menopause were therefore the most important determinants of breast cancer risk. The effects of the timing of births was significantly heterogeneous in pre- and postmenopausal women because of the transient adverse effect of such events, evident only in premenopausal women. Back to Top
| Studies which show a link between delayed first full term pregnancy and breast cancer |
-
TITLE: Influence of age and parity on the development of the human breast. AUTHORS: Russo J; Rivera R; Russo IH
AUTHOR AFFILIATION: Department of Pathology, Fox Chase Cancer Center, Philadelphia, PA 19111.
SOURCE: Breast Cancer Res Treat 1992;23(3):211-8
CITATION IDS: PMID: 1463860 UI: 93099284 ABSTRACT:
Breast cancer is heavily influenced by the reproductive history of the individual. Pregnancy has a protective effect which is attributed to differences in the degree of differentiation of the breast. The purpose of this work was to determine whether the quantity and the type of parenchymal structures present in the human breast were related to the age and parity history of a woman. Fifty-one human breast samples were obtained from bilateral or unilateral reduction mammoplasties performed in 40 parous women ranging in age from 18 to 57 years, and 11 nulliparous women ranging in age from 14 to 54 years. An average of 100 grams of tissue/specimen were processed for whole mount. A total of 650 slides were examined and 31,222 structures were classified and counted under the light microscope. The following mammary structures were identified: terminal structures (TS), and lobules (LOB) type 1, 2, and 3. Results were plotted for the total patient population and separately for nulliparous and parous women against age. The total patient population contained similar proportions of LOb1, 2, and 3 between ages 14-18, with a reduction of percentage of Lob1 and increase in Lob3 between ages 23 to the middle forties, when Lob3 decreased and Lob1 increased to 70%. Lob2 and TS did not exhibit significant changes throughout the period of life analyzed. When analyzed separately it was found that the breasts of nulliparous women were predominantly composed of Lob1, fewer Lob2, with Lob3 almost completely absent, whereas parous women had a high frequency of Lob3, which were the predominant structures until the fourth decade of life.(ABSTRACT TRUNCATED AT 250 WORDS) Back to Top
| Studies which did not show an increased risk: |
TITLE: The influence of medical conditions associated with hormones on the risk of breast cancer
AUTHORS: Moseson M; Koenig KL; Shore RE; Pasternack BS
SOURCE: Int J Epidemiol 1993 Dec;22(6):1000-9
ABSTRACT: Medical conditions related to hormonal abnormalities were investigated in a case-control study of breast cancer among women who attended a screening centre. Information was obtained by telephone interview regarding physician-diagnosed medical conditions such as thyroid or liver diseases, diabetes, and hypertension, as well as hirsutism, acne, galactorrhoea, and reproductive, menstrual, and gynaecological factors. Results are presented for 354 cases and 747 controls. Women with fertility problems who never succeeded in becoming pregnant were at significantly increased breast cancer risk (adjusted odds ratio [OR] = 3.5; 95% confidence interval [CI]:1.1-10.9). An elevated cancer risk was also associated with having excess body hair (OR = 1.5; 95% CI:1.0-2.3), or having excess body hair in addition to persistent adult acne (OR = 6.8; 95% CI:1.7-27.1). Recurrent amenorrhea (OR = 3.5; 95% CI:1.1-11.5), and a treated hyperthyroid condition (OR = 2.2; 95% CI:1.1-4.4) were significantly associated with risk. A non-significant elevation of risk was present for endometrial hyperplasia (OR = 1.8; 95% CI: 0.8-4.0). There was a suggestion of an association between a history of galactorrhoea and breast cancer risk (OR = 2.0; 95% CI:0.8-4.9) among premenopausal women. No associations were found with other medical or gynaecological factors. The possibility that some of these findings are due to chance cannot be excluded because of the problem of multiple comparisons. Back to Top TITLE: Induced abortion and the risk of breast cancer [see comments]
AUTHORS: Melbye M; Wohlfahrt J; Olsen JH; Frisch M; Westergaard T; Helweg-Larsen K; Andersen PK
AUTHOR AFFILIATION: Department of Epidemiology Research, Danish Epidemiology Science Center, Statens Serum Institut, Copenhagen, Denmark. SOURCE: N Engl J Med 1997 Jan 9;336(2):81-5
COMMENT: Comment in: N Engl J Med 1997 Jan 9;336(2):127-8
Comment in: N Engl J Med 1997 Jun 19;336(25):1834; discussion 1835
Comment in: ACP J Club 1997 Jul-Aug;127(1):18 NOTE FROM THE COALITION: The 1997 Melbye study, which is also known as the Danish study, received a considerable amount of press coverage because the study concluded that there was no significant link between abortion and breast cancer. Journalists were impressed with the study's size: 1.5 million women. However, this study has been severely criticized for its misclassification and data adjustment errors. For example, the researchers followed non-abortive women more than twice as long as the women who did have elective abortions. They compared a smaller group of younger women (280,691) who had had abortions to a far larger number of older women (1,248,541) who hadn't procured abortions. The difficulty with this practice is obvious. Women who live longer have a greater chance of developing breast cancer. (See Dr. Joel Brind's web site, "Rotten in Denmark," www.abortioncancer.com.)
Moreover, even this study reported that "[w]ith each one-week increase in
the gestational age of the fetus . . . there was a 3 percent increase in the
risk of breast cancer." The relative risk was found to increase from 0.81 due
to induced abortion at under seven weeks of gestation to a statistically
significant 1.89 after eighteen weeks of gestation. The Melbye researchers
noted that "The increased risk among women who had had second-trimester
abortions finds biologic support in experiments in rats and is in line with
the hypothesis of Russo and Russo."
Dr. Brind and his colleagues believe that this study actually masked a
statistically significant risk increase. It is interesting that the Melbye
researchers corrected some of these errors in a 1999 study, but declined to
admit that they were doing so and did not provide a reanalysis of their
induced abortion data from the earlier study. [Joel Brind and Vernon
Chinchilli, Letter, "Induced Abortion and Risk of Breast Cancer," II Epidemiol
ogy 234-235 (2000)]. The Brind team intends to do this job for the Melbye
researchers.
The Melbye team reported in their 1999 study that premature birth before
32 weeks gestation more than doubles the breast cancer risk which the woman would have had had the pregnancy continued to full term.
Interestingly, the New England Journal of Medicine which published the
1997 study acknowledged abortion as a risk factor less consistently associated with breast cancer in the text of an article discussing risk factors for breast cancer written by Katrina Armstrong in February, 2000. However, the NEJM's acknowledgment understated the increased risk. [Armstrong (2000) NEJM 342:564-71].
ABSTRACT:
BACKGROUND: It has been hypothesized that an interrupted pregnancy might increase a woman's risk of breast cancer because breast cells could proliferate without the later protective effect of differentiation. METHODS: We established a population-based cohort with information on parity and vital status consisting of all Danish women born from April 1, 1935, through March 31, 1978. Through linkage with the National Registry of Induced Abortions, information on the number and dates of induced abortions among those women was combined with information on the gestational age of each aborted fetus. All new cases of breast cancer were identified through linkage with the Danish Cancer Registry. RESULTS: In the cohort of 1.5 million women (28.5 million person-years), we identified 370,715 induced abortions among 280,965 women (2.7 million person-years) and 10,246 women with breast cancer. After adjustment for known risk factors, induced abortion was not associated with an increased risk of breast cancer (relative risk, 1.00; 95 percent confidence interval, 0.94 to 1.06). No increases in risk were found in subgroups defined according to age at abortion, parity, time since abortion, or age at diagnosis of breast cancer. The relative risk of breast cancer increased with increasing gestational age of the fetus at the time of the most recent induced abortion: <7 weeks, 0.81 (95 percent confidence interval, 0.58 to 1.13); 7 to 8 weeks, 1.01 (0.89 to 1.14); 9 to 10 weeks, 1.00 >12 weeks, 1.38 (1.00 to 1.90) (reference category, 9 to 10 weeks). CONCLUSIONS: Induced abortions have no overall effect on the risk of breast cancer. Back to Top
Abortion history and breast cancer risk: results from the Shanghai breast cancer study.
Amer J Epidemiology, June 1, 2000;151 (11)
M Sanderson, XO Shu, F Jin, Q Dai, WQ Wen, Y Hui, YT Gao, W Zheng (university of South Carolina, SC, 29208)
Studies of the association between induced abortion and breast cancer risk
have been inconsistent, perhaps due to suspected underreporting of abortions. Induced abortion is a well-accepted family control procedure in China, and women who have several induced abortions do not feel stigmatized. The authors used data from a population case-control study of breast cancer among women age 25 to 64 conducted between 1996 and 1998 in urban Shanghai to assess whether a history and number of induced abortions was related to breast cancer risk. In-person interviews were completed with 1459 incident breast cancer cases ascertained through a population-based cancer registry, and 1556 controls randomly selected from the general population in Shanghai (with respective response rates of 91% and 90%). After adjusting for confounding, there was no relation between ever having had an induced abortion and breast cancer (odds ratio [OR] 1.0; 95% confidence interval [CI] 0.8-1.2). While women who had 3 or more induced abortions were not at increased risk of premenopausal breast cancer (OR 0.9; 95% CI 0.6-1.3) there was an elevated risk of postmenopausal breast cancer (OR 1.6, 95% CI 0.9-2.8). Among women whose first birth was at age 26 or older, the effect of having 3 or more abortions differed by menopausal status (premenopausal : OR 0.4, 95% CI 0.2-0.8; postmenopausal: OR 1.7, 95% CI 0.9-3.3). These results suggest that a history of several induced abortions may influence risk of premenopausal and postmenopausal breast cancer differently.
Back to Top TITLE: Absence of association between reproductive variables and the risk of breast cancer in young women in Sweden and Norway.
AUTHORS:Adami HO; Bergstrom R; Lund E; Meirik O
SOURCE: Br J Cancer 1990 Jul;62(1):122-6 ABSTRACT: A population-based case-control study was conducted in Sweden and Norway to analyse possible associations between breast cancer occurring before the age of 45 and several different characteristics of the women's reproductive life. A total of 422 (89.2%) of all eligible patients, and 527 (80.6%) of all eligible controls were interviewed. In univariate analyses, different characteristics of child-bearing (parity, age at first birth, years between last birth and diagnosis, duration of breast-feeding, and number of induced and spontaneous abortions), measures of the fertile or ovulating period (age at menarche, years between menarche and first pregnancy, and estimates of the menstruation span) and symptoms of anovulatory cycles or infertility were all seemingly unrelated to, or at most weakly associated with breast cancer. Adjustment for possible confounding factors in multivariate analyses resulted in largely unaltered risk estimates with odds ratios close to unity and without any significant trends when the exposure variables were studied in categorised or in continuous form. We conclude that reproductive factors did not explain the occurrence Back to Top
| Other Studies of Interest: |
TITLE: Preterm delivery and risk of breast cancer.
AUTHORS: Melbye M; Wohlfahrt J; Andersen AM; Westergaard T; Andersen PK AUTHOR AFFILIATION: Danish Epidemiology Science Centre, Statens Serum Institut, Copenhagen.
SOURCE: Br J Cancer 1999 May;80(3-4):609-13
CITATION IDS: PMID: 10408874 UI: 99314793
ABSTRACT:
To explore the risk of breast cancer in relation to the length of a pregnancy we tested whether a preterm delivery carries a higher risk of breast cancer than does a full-term delivery. Based on information from the Civil Registration System, and the National Birth Registry in Denmark, we established a population-based cohort of 474 156 women born since April 1935, with vital status and detailed parity information, including the gestational age of liveborn children and stillbirths. Information on spontaneous and induced abortions was obtained from the National Hospital Discharge Registry and the National Registry of Induced Abortions. Incident cases of breast cancer in the cohort (n = 1363) were identified through linkage with the Danish Cancer Registry. The period at risk started in 1978 and continued until a breast cancer diagnosis, death, emigration, or 31 December, 1992, whichever occurred first. After adjusting for attained age, parity, age at first birth and calendar period, we observed the following relative risks of breast cancer for different lengths of the pregnancy: < 29 gestational weeks = 2.11 (95% confidence interval 1.00-4.45); 29-31 weeks = 2.08 (1.20-3.60); 32-33 weeks = 1.12 (0.62-2.04); 34-35 weeks = 1.08 (0.71-1.66); 36-37 weeks = 1.04 (0.83-1.32); 38-39 weeks = 1.02 (0.89-1.17); 40 weeks = 1 (reference). Parous women who had a preterm delivery below 32 weeks gestation had a 1.72-fold (1.14-2.59) increased risk of breast cancer compared with other parous women. In conclusion, a preterm delivery of 32+ weeks gestation did not significantly increase a woman's risk of contracting breast cancer. Only for the very small group of women with preterm deliveries of less than 32 weeks gestation did we observe an increased risk. MAIN MESH HEADINGS: Breast Neoplasms/*epidemiology
Back to Top
TITLE: HCG, HPL, oestradiol, progesterone and AFP in serum in patients with threatened abortion. AUTHORS: Kunz J; Keller PJ
SOURCE: Br J Obstet Gynaecol 1976 Aug;83(8):640-4
CITATION IDS: PMID: 60125 UI: 76253418 ABSTRACT:
The predictive value of various biochemical methods for monitoring early risk pregnancies has been compared in 65 cases of threatened abortion. Estimation of human chorionic gonadotropin (HCG), human placental lactogen (HPL), progesterone, oestradiol and alpha-fetoprotein (AFP) in serum were made by radioimmunoassays. Values below the normal range predicted abortion in 79, 81, 89, 92 and 38 per cent of patients, while normal values confirmed continuation of pregnancy with an accuracy of 71, 61, 60, 68 and 30 per cent respectively. Thus predictions from oestradiol and progesterone were at least as reliable as those from the protein hormones, while AFP proved to be unsuitable for this purpose. Combination of two variables gave even more reliable results. Due to individual and diurnal variation, however, abortion in the third and fourth month could not be definitely assumed at values above 5 IU HCG/ml, 5 ng progesterone/ml or 200 pg oestradiol/ml. Back to Top TITLE: Susceptibility of the mammary gland to carcinogenesis. II. Pregnancy interruption as a risk factor in tumor incidence. AUTHORS: Russo J; Russo IH
SOURCE: Am J Pathol 1980 Aug;100(2):497-512
CITATION IDS: PMID: 6773421 UI: 80263202 ABSTRACT:
In the rat, pregnancy and lactation prior to carcinogen administration protect the mammary gland from developing carcinomas and benign lesions. In this study, the influence of pregnancy interruption versus full pregnancy and pregnancy plus lactation on the incidence of carcinomas and benign lesions was studied in the mammary glands of rats treated with 7,12-dimethylbenz(a)anthracene (DMBA). Fifty-nine Sprague-Dawley rats were separated into 5 groups: I) rats that had had one pregnancy and one lactation; II) rats that had had one pregnancy without lactation; III) rats that had had pregnancy interrupted at the 12th day of gestation; IV) age-matched virgin rats as a control Group I; and V) age-matched virgin rats as a control for groups II and III. The 5 groups received a single intragastric dose of DMBA (10 mg/100 g body weight), with the exception of 2 animals per group, which were killed 1 hour after an intraperitoneal injection of 2.5 mu Ci 3H-thymidine/g body weight. The number of labeled nuclei per 100 cells (DNA labeling index, LI) was counted in terminal end buds (TEBs), terminal ducts (TDs), and alveolar buds (ABs) of the glands. The number of structures and the DNA-LI were correlated with the incidence of tumors at 22 weeks after DMBA. Pregnancy, with or without lactation, resulted in elimination of TEBs and reduction in the DNA-LI of TDs and ABs. These groups did not develop carcinomas. After the interruption of pregnancy the mammary gland contained numerous TEBs, with a high DNA-LI; 77% of these animals developed carcinomas, and all of them developed benign lesions. Therefore, while pregnancy and lactation protected the mammary gland from developing carcinomas and benign lesions by induction of full differentiation, pregnancy interruption did not elicit sufficient differentiation in the gland to be protective, and these animals were at the same risk as virgin animals treated with the carcinogen. Back to Top TITLE: A record-based evaluation of induced abortion and breast cancer risk (United States). Newcomb PA, Mandelson MT. Cancer Prevention Research Program, Fred Hutchinson Cancer Research Center, Seattle, WA 98104, USA. OBJECTIVE: Previous studies of induced abortion and breast cancer may have been limited by differential reporting of abortion history. We conducted a population-based case-control study to evaluate abortion (both induced and spontaneous) and breast cancer risk. METHODS: All study subjects were aged 20-69 years and members of Group Health Cooperative of Puget Sound (GHC). Incident invasive breast cancer cases (n = 138) were identified from the linkage between the GHC enrollment file and the Seattle-Puget Sound SEER Cancer Registry. Controls (n = 252) were randomly selected from GHC enrollment files and matched to cases on age and enrollment period. All subjects had to have been enrolled at GHC for the 2 years preceding diagnosis (cases) or reference (controls) date. The unified medical record of each case was abstracted for pregnancy history, including prior induced and spontaneous abortions, menopause status, height and weight, screening practices, and other risk factors. RESULTS: Compared to all women who had never had an induced abortion, the multivariate adjusted relative risk of breast cancer in women with an induced abortion was 0.9 (95% confidence interval 0.5-1.6). This risk was similar in parous women, and nulliparous women. There was no association between spontaneous abortion and breast cancer risk. CONCLUSIONS: These results do not support a relation between induced abortion and breast cancer incidence. Back to Top
|