Having a close family member who's had lung cancer doubles your own risk for the disease -- even if you don't smoke.
The finding comes from a 13-year study of more than 102,000 Japanese men and women. Study participants were aged 40 to 69 at the start of the study. Over the study period, nearly 800 participants developed lung cancer.
Jun-Ichi Nitadori, MD, and colleagues report in the October issue of the journal Chest that:
--Having a parent or sibling with lung cancer doubles a person's risk of lung cancer.
--The risk of inherited lung cancer is greater for women (2.65-fold risk) than for men (1.69-fold risk).
--The risk of inherited lung cancer is greater for people who never smoked (2.48-fold risk) than for current smokers (1.73-fold risk).
--Squamous cell carcinoma is the type of lung cancer most strongly linked to family history.
--Only a family history of lung cancer -- not other kinds of cancer -- is linked to inherited lung-cancer risk.
The increased risk of lung cancer among families cannot be explained simply by shared smoking habits, Nitadori and colleagues find.
The Japanese findings support more than 40 years of previous studies suggesting that lung cancer risk can be inherited. These studies have been criticized for failing to completely control for smoking behaviors. And nobody has yet discovered a "lung cancer gene."
But the consistency of the findings suggest that the time has come to add family history to the known risk factors, argues Wayne State University researcher Ann G. Schwartz, PhD, MPH, in an editorial accompanying the Nitadori study.
"Family history should be tested as another marker of 'high risk' for lung cancer in [screening and prevention] trials," Schwartz suggests.
Moreover, Schwartz suggests, current smokers might be more motivated to quit if they knew they had inherited higher lung cancer risk from their parents.
By Daniel J. DeNoon, reviewed by Louise Chang, MD
SOURCES: Nitadori, J. Chest, October 2006; vol 130: pp 968-975. Schwartz, A.G. Chest, October 2006; vol 130: pp 936-937.