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Friday, September 4, 2015
Is Lung Cancer Genetic?
My mother died of lung cancer at the age of 48 almost a year ago. Afterwards, I became very worried about my 16 year old sister and myself. She had NSCLC, and was a heavy marijuana smoker and a moderate cigarette smoker for most of her adult life. I researched a family history and there are some spatterings of breast, ovarian, and colon cancers. Only one relative other than my mom had lung cancer and that was my great-great uncle. I think he was by marriage. Anyway, are my sister, myself and my aunt and uncle (her brother and sister) at a hugely increased risk for dying of the same horrible thing that took her? I do not smoke but have been exposed to second hand smoke. I am very scared of suffering the same fate. Am I really at a 95% risk of contracting this and is it true that it would most likley be 10 years younger than the age my mom was diagnosed? If that is true, I have 8 years.
One last question, is her age of diagnosis a big concern? Would that be considered an extremely young age? I have spoken to a genetic counselor who said that it is in a general pattern and not overly concerning. Is she correct?
Thank you for visiting NetWellness. A question similar to yours has been previously addressed, so I have included a portion of that answer. But briefly, no, you, your sister and your aunt and uncle are not likely to be at high risk for lung cancer. It is unlikely that you have a 95% chance to develop lung cancer over your lifetime.
Research suggests that having a family history of cancer predisposes close relatives (children, brothers and sisters) to the same kind of cancer. This would mean that you have a somewhat higher chance of developing lung cancer than the average individual your age. Most estimates are that lifetime cancer risk is about doubled; this applies to lung cancer as well as most other cancers.
The lifetime risk to develop lung cancer for Americans is about 7%; however, the majority of individuals who develop lung cancer are smokers so the risk for a non-smoker is probably somewhat less. But if you use the population risk for lung cancer, your chance will be somewhere around 10-12%, taking into account that your mother had lung cancer .
Lung cancer is sometimes found in some of the hereditary cancer syndromes, but the information you provide about other cancers in the family is not highly concerning.
Your best option is to discuss your family history with your primary care physician and come up with a screening plan that covers the typical cancers for people of your age. You can also try to minimize your future exposure to known environmental factors associated with increased cancer risk (such as cigarette smoke). If you wish to discuss the possibility of a genetic influence in your family, you can contact a genetic counselor in your area and schedule an appointment to go over this information in more detail. The websites for the National Society of Genetic Counselors and the National Cancer Institute are listed below.
With regard to the age at which your mother was diagnosed, I agree with what the genetic counselor previously told you. The "10 year rule" that you refer to, is that screening for cancer generally should start about 10 years earlier than the cancer was diagnosed in the family; it does not mean that you will develop cancer 10 years earlier than the relative developed cancer. The intention is to start screening earlier so that it will be detected at early stages if it develops.
Duane D Culler, PhD, MS
Clinical Instructor of Genetics
School of Medicine
Case Western Reserve University