My name is Robert Resta, and I'm a certified genetic counselor working at the Hereditary Cancer Clinic at Swedish Cancer Institute in Seattle. Dr. West asked me if I might provide a few general comments about the genetic contribution of lung cancer.

In truth, this is a complicated question. There is little doubt that more than 90% of lung cancer can be directly attributed to tobacco use. The tendency to smoke cigarettes runs in families, and relatives of smokers often have greater exposure to second-hand smoke, making it very difficult to tease out genetic factors from environmental influences. Research studies on genetic and familial factors have produced conflicting results and conclusions.

Despite the strong influence of cigarette smoking on lung cancer risk, genetics no doubt plays some - likely small - role. Studies of lung cancer in families have shown a slightly greater risk of developing lung cancer among relatives of lung cancer patients. Overall, though, if you have lung cancer, the vast majority of your non-smoking siblings, children, cousins and other relatives will never develop lung cancer. Nonetheless, having a relative with lung cancer can up to double a person’s risk of developing lung cancer, especially among smokers. The risk of lung cancer is also greater - but still low - in relatives of lung cancer patients who never smoked and who developed the disease before age 50.

Further complicating the picture is that the lung is a common site of metastasis for other cancers. Thus, an aunt who was diagnosed with lung cancer may in fact have had breast cancer that spread to her lungs, but the cancer was not diagnosed until it reached the lung. While this is not a true lung cancer, in many families, breast cancer that spreads to the lung is often incorrectly but understandably called “lung cancer”. Having a family history of breast, ovarian, or colon cancer can increase your own risk of developing certain cancers.

Some studies have found that certain genetic markers may be associated with a slightly higher or lower risk of developing lung cancer. However, no genetic test can reliably predict who will or will not develop lung cancer, either among smokers or non-smokers. The most effective way to lower your risk of developing lung cancer is to never smoke or to quit smoking.

Some cancers can have a significant hereditary component, particularly certain forms of breast, ovarian, and lung cancers. Whether or not you have lung cancer, reviewing your family history can be very helpful in determining your risk of developing other cancers. The relatives of greatest concern are your siblings, nieces, nephews, parents, grandparents, aunts, uncles, and cousins. The types of information you should collect about them are their ages; if they are deceased, their age at death and cause of death; major health problems, not just cancers; if they have had a cancer, the specific type of cancer and the age at diagnosis; if possible, obtain medical records to verify cancer diagnoses since information can be miscommunicated or misunderstood within families; and your ancestry (certain populations have greater risks for certain kinds of cancers, such as stomach cancer among Japanese, and hereditary breast/ovarian cancer among Ashkenazi Jews). Your physician and a genetic counselor can review your family history to help determine if you are at greater hereditary risk for specific cancers, and what you can do to detect or prevent those cancers.
Bottom Line: If you have a relative with lung cancer, and you are not a smoker, the odds are very low that you will develop lung cancer.

On-Line Resources
Find A Genetic Counselor:
- National Society of Genetic Counselors http://www.nsgc.org/
- National Cancer Institute Genetic Services Directory http://www.cancer.gov/search/geneticsservices/

Lung Cancer Risk Prediction:
Memorial Sloan-Kettering Cancer Center http://www.mskcc.org/mskcc/html/12463.cfm

Lung Cancer Information:
National Cancer Institute http://www.cancer.gov/cancertopics/types/lung