First-degree relatives of lung cancer patients have a 2 to 3.5 times greater risk of developing lung cancer than the general population, and tobacco smoke plays a major role, even among those with a genetic predisposition, according to a study in the December 22/29 issue of JAMA.
Lung cancer is the leading cause of death from cancer among men and women in many Western countries, according to background information in the article. Death due to lung cancer in the United States exceeds the death rate from breast, prostate, and colon cancer combined. The dominant role of tobacco smoke as a causative factor in lung cancer has been well established. Other studies have indicated that there may be an inherited predisposition to lung cancer, but data have been limited.
Steinn Jonsson, M.D., of the Landspitali-University Hospital, Reykjavík, Iceland, and colleagues examined the contribution of genetic factors to the risk of developing lung cancer in the population of Iceland. The risks for developing lung cancer for first-, second-, and third-degree relatives of patients with lung cancer were estimated by linking records from the Icelandic Cancer Registry (ICR) of all 2,756 patients diagnosed with lung cancer within the Icelandic population from January 1, 1955, to February 28, 2002, with an extensive genealogical database containing all living Icelanders and most of their ancestors since the settlement of Iceland. The risk for smoking was similarly estimated using a random population-based group of 10,541 smokers from the Reykjavik Heart Study who had smoked for more than 10 years. Of these smokers, 562 developed lung cancer based on the patients with lung cancer list from the ICR.
“The nationwide genealogy database used in our study provided a means for uncovering the familial component by revealing more connections between patients, missed in most other populations,” the authors write.