Scientists at the University of Washington and Fred Hutchinson Cancer Research Center presented their results in the October 1 issue of Cancer Research, a journal of the American Association for Cancer Research.
They studied a concept called fetal microchimerism, which is the ability of cells from a growing unborn baby to take up long-term residence in the mother's body.
Vijayakrishna K. Gadi, M.D., Ph.D., assistant professor at the University of Washington and research associate at the Fred Hutchinson Cancer Research Center, discussed the findings in a statement LifeNews.com obtained.
"Our research found that these persisting fetal cells may be giving a woman an edge against developing breast cancer, he said. This experiment of nature is all the more fascinating because for years doctors treated a number of different cancers by transplanting cells from one person to another."
Fetal microchimerism has been implicated as a mechanism of autoimmune disease but it may also benefit mothers by putting the immune system on alert for malignant cells to destroy.
The researchers recruited 82 women, 35 of whom had been diagnosed with breast cancer.
Approximately two-thirds of the women studied have had children, and more than half of the participants had given birth to at least one son. That's important because the scientists examined whether any of the women had the male Y chromosome among female cells in a blood sample.
Among the women with breast cancer, only five had male DNA in their bloodstream.
Three of the five previously gave birth to sons, one had had an abortion and the other had never been knowingly pregnant.
In total, about 14 percent of all women in the breast cancer group had male DNA in their bloodstream compared to 43 percent of women in the non-breast cancer group.
According to Dr. Gadi, these findings could provide a starting point for future research on the role of fetal microchimerism in the prevention of cancer.
And pro-life groups say the findings show women should be encouraged to have children instead of having abortions as it helps protect them from contracting breast cancer.