Family Ties Possibly Responsible for Lung Cancer in Nonsmokers
Jan. 28, 2000 (Baltimore) -- Having a first-degree relative -- a parent, brother, sister, or child -- with cancer is associated with an approximate doubling of lung cancer risk among people who don't smoke. "Lots of studies have linked lung cancer and relatives with cancer among smokers, but this is the first study to address the issue among nonsmokers with lung cancer," says Susan Mayne, PhD, in an interview with WebMD. "The association suggests that a genetic predisposition may play a role."
The study looked at over 400 nonsmokers who were diagnosed with lung cancer and compared them to the same number of nonsmokers without lung cancer. Both groups were asked to report their family history of any type of cancer.
People with lung cancer were more likely to have had fathers with any type of cancer. Also, mothers of lung cancer patients were twice as likely to have been diagnosed with breast cancer. Brothers and sisters were about one and a half times more likely to have had any type of cancer compared to the people without lung cancer. "We expected to see more cancers of the throat and mouth among family members of those with lung cancer, but we didn't expect to see the association with breast cancer," says Mayne, who is associate professor of epidemiology at Yale University School of Medicine and lead author of the study. The results appear in the December issue of the journal Cancer, Epidemiology, Biomarkers and Prevention.
As far as the association with breast cancer and lung cancer is concerned, Stephen Baylin, MD, says, "If someone inherits a gene for colon cancer, for example, it may certainly operate in other tissues in the body. I think this study further illustrates that while genetics plays a role, the process of cancer development is multifactorial." Baylin, who is professor of oncology and cancer biology at Johns Hopkins University in Baltimore, gave objective commentary on the study in an interview with WebMD.
Mayne says she would like to see the results of the study repeated in another study of cancers in relatives of those with cancer. "Our study may suggest a place to look for genetic changes that may predispose to cancer," she says.
Says Baylin, "Even for smokers, there is evidence that some people will develop cancers more quickly than others and some never develop cancer at all, so there is clearly a role for genetics. However, for the common cancers, it may take four or five different genetic predispositions working together for cancer to develop."