Can I Get Lung Cancer If I Don’t Smoke?

Dr. Jeffrey Crawford, MD, George Barth Geller Distinguished Professor and Professor of Medicine, explains the relationship between smoking and lung cancer.

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Host: Lindsay Key

Welcome to Headscratchers, a mini-cast from the Duke University School of Medicine. We ask Duke experts to help us understand the questions in science that have us scratching our heads. Today we're speaking with Dr. Jeffrey Crawford, an expert in lung cancer. Dr. Crawford, my aunt lived her entire life without smoking but developed lung cancer. My uncle smoked his whole life and never developed lung cancer. How can that be?

Dr. Crawford

Well, I think in that question is the question is smoking always related to lung cancer, and do all patients who smoke get lung cancer? And the answer to that is no, they don't. But what's important from the uncle's perspective is that smoking is associated with 480,000 deaths per year in the United States, of which about 150,000 are due to lung cancer. So the other major causes of death from smoking, are heart disease. plus a host of other cancers, head and neck cancer, pancreatic cancer, kidney cancer, cervical cancer, colon cancer all have some relationship to smoking, as well as some others. So the point is that if you're an active smoker, you're likely to live 10 years less than if you never smoked. So for the uncle who may not have developed lung cancer, he certainly suffered in some way from his lifelong smoking.

Now, the aunt, on the other hand, falls into a group of never smokers who developed lung cancer. As many as 20% of patients who develop lung cancer never smoked, or had very minimal smoking exposure. And that's probably because there are other causes. We think radon is a cause we think chemical exposure in the workplace, air pollution, all can contribute to lung cancer risk. Second hand smoking is a significant risk. Perhaps 7 or 8,000 people a year die from lung cancer due to secondhand smoke. More than 30,000 people secondhand smoke die from heart disease. So secondhand smoke is a big deal.

Now, the other thing that we've learned from the never smoker population is that they harbor a significant number of genetic mutations that occur in the tumors that may be driving the cancer. That can happen in smokers but more common in the never smoker. We don't know why that occurs. But that's leading us to develop new techniques and new treatments just for those never smokers, we have these we call targetable mutations. That mutation, we can sometimes target with a specific drug that blocks the effect of that mutation on the cancer cell and ultimately destroys the cancer. The smoking/never smoking relationship has helped us really understand that lung cancer comes in many different varieties. There's not one lung cancer, there's one lung cancer for every patient that has it. And personalized medicine is the way to approach that.

Now returning to the uncle one more time, it's never too late to quit smoking. So you never want to start smoking, but it's never too late to quit. If you are under the age of 40, and you quit smoking, you can reduce your risk of dying by 90% from smoking related causes. And that'll decrease over time, but even in people over 70, quitting smoking can reduce the risk of some of these other causes. So if you smoke, stop.

Host: Lindsay Key

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