Posted on 04/02/2008 9:25:13 PM PDT by kiriath_jearim
WASHINGTON -- Why do some 90-year-old chain smokers avoid lung cancer, while other people who smoke far less wind up dying of the disease? How can some people light up now and then without getting hooked, while others are addicted practically from their first puffs?
The answer, at least in part, may be in your genes.
Scientists have identified certain genetic variations that appear to make people more likely to get hooked on cigarettes and more prone to develop lung cancer.
The findings could someday lead to screening tests and customized treatments for smokers trying to kick the habit.
The discovery by three separate teams of scientists makes the strongest case so far for the biological underpinnings of nicotine addiction and sheds more light on how genetics and lifestyle habits join forces to cause cancer.
"This is kind of a double whammy gene," said Christopher Amos, a professor of epidemiology at the M.D. Anderson Cancer Center in Houston and author of one of the studies. "It also makes you more likely to be dependent on smoking and less likely to quit smoking."
A smoker who inherits these genetic variations from both parents has an 80 percent greater chance of lung cancer than a smoker without the variants, the researchers reported. And that same smoker on average lights up two extra cigarettes a day and has a much harder time quitting than smokers who don't have these genetic differences.
The researchers disagreed on whether the variants directly increased the risk of lung cancer or did so indirectly, by causing more smoking.
The three studies, funded by governments in the U.S. and Europe, are being published Thursday in the journals Nature and Nature Genetics.
The scientists studied the genes of more than 35,000 white people of European descent in Europe, Canada and the United States. Blacks and Asians will be studied soon and may yield different results, scientists said.
They aren't quite sure if what they found is a set of variations in one gene or in three closely connected genes. But the gene variations govern nicotine receptors on cells.
"This is really telling us that the vulnerability to smoking and how much you smoke is clearly biologically based," said psychiatry professor Dr. Laura Bierut of Washington University in St. Louis, a genetics and smoking expert who did not take part in the studies. She praised the research as "very intriguing."
The new studies are surprising in that they point to areas of the genetic code that are not associated with pleasure and the rewards of addiction.
That may help explain why some people can quit and others fail, said Dr. Nora Volkow, director of the National Institute of Drug Abuse in Bethesda, Md., which funded one of the studies.
"It opens our eyes," Volkow said Wednesday. "Not everyone takes drugs for the same reason. Not everyone smokes cigarettes for the same reasons."
One clue is in the location of the just-discovered variants, on the long arm of chromosome 15, Volkow said. It is in an area that, when damaged during tests on animals, makes them depressed and anxious. While some people smoke because it helps them focus or gives them a physiological reward, others do it to stave off depression.
That suggests that adding anti-depressants to some smokers' treatment could help them kick the habit.
Bierut said a simple, inexpensive test could be developed to screen people for the variants. Kari Stefansson, lead author of the largest of the three studies, agreed. He is chief executive of deCode Genetics of Iceland, which already does prostate cancer genetic tests.
Such testing could carry risks all its own, bioethicist Arthur Caplan of the University of Pennsylvania warned. People who have been found to have a genetic predisposition to addiction and lung cancer could find it harder to get health or life insurance, or their employer might drop their coverage, he said.
"The good news is that getting these risk estimates will help focus anti-smoking campaigns, and some people will want to voluntarily get into anti-addiction programs early, where they will probably work better," Caplan said in an e-mail. But if such testing is done, it should be voluntary, and the results should be kept private, he said.
Smoking-related diseases worldwide kill about one in 10 adults, according to the World Health Organization.
21%
Approximate smoking rate among U.S. adults.
42%
The smoking rate among
U.S. adults in 1965.
10%
The number of adults worldwide killed by smoking-related diseases, according to the World Health Organization.
Even after 7 years without a single puff, I still crave them on occasion.
It sure would be nice to know if I've got the gene they're talking about!
Wonder if that’s the same gene makes folks ride Harleys and live in trailer parks?
I’m an older tobacco user but now am probably less than 5% of my heyday. No urge anymore.
Wow, that's funny.
However, you had better put on your flak jacket.
I don’t know any Harley riders that live in trailer parks. The folks in trailer parks usually ride jap weenie bikes.
“This is kind of a double whammy gene,” said Christopher Amos, a professor of epidemiology at the M.D. Anderson Cancer Center in Houston and author of one of the studies.
This comment strikes me as childlike . How about just growing a pair filled with sand , set a goal then do something about it ?
And I think that genetic predispositions towards cancer have been established for decades now.
I would give you H3ll for that, but... I think you’re on to soemthing....
I think Rev Wrong calls that ‘typical whitey’
My dad lived in a trailer park, has a Harley, but he quit smoking.........
I lived in a trailer park growing up, and I smoke; now if I only had a Harley.......
No wait a minute, this is my chance to achieve victim’s class status. I find that offensive; its society’s fault. /sarc
And for those of you wondering... No, we never received social benifits. He got a new job and made it out. At age 17 after I finished Boot Camp, he handed me a $20 to put in the gas tank for the drive to Lejeune. I’ve been on my own ever since and bought my first house at 20. Onna dem real fancy stick-built jobbers; you know they kind that ain’t never had no wheels.
I ride and own 2 Harleys (around $60k worth) and I don’t live in a trailer park.....but that was good enough for a smile.
“Some of us just have addictive personalities. We don’t like to do anything in moderation.”
THAT would be me.
I quit smoking once, quit drinking, swearing and chasing wild women. It was the longest 20 minutes of my whole life.
I've quit smoking hundreds of times. At age 58, I figure I only got one more quit left in me.
Good one. ;>)
It’s bad enough that you ain’t got no Harley, just don’t ever quit cookin’ in the back of yer truck. ;>)
My life would have been easier if I had discovered that character flaw before I discovered alcohol and tobacco. Fortunately I did become aware of it however and I at least had enough sense to avoid more harmful drugs. While living in Seattle during the late 80’s and early 90’s I watched a few friends descend into heroin addiction. By that time however I definitely knew that I could become addicted and I wouldn’t touch the stuff with a 10’ pole.
For 37 years, my Bride has been the lion tamer, or God only knows where I would have been.
I have slowed down a bit at 59, but that risk thing (adrenaline junkie)..... is still there. ;>)
My father smoked for 50 years. Doctor told him to quit and he did. Cold Turkey. Never touched another one. Never acted differently or complained. Lived into his 80s.
Potential route for smoking regulations under ADA guidlelines?
If you've got the gene...lite up if you know what I mean.
Don’t worry I won’t. ‘specially since the truck ain’t going anywhere with the tranny in the tub and all.
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