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mutation that can be detected in the tumor, and there are drugs and therapeutics available for them. At Yale, we have a very active research program aimed at targeting those cancer cells that contain the mutation.”
What is lung cancer?
Lung cancer, one of the most common cancers in the world, is a leading cause of cancer-related death in men and women in the United States. While smoking cigarettes is by far the most common cause of lung cancer, risk factors also include a family history of lung cancer and certain environmental contributors.
Like all cancers, lung cancer begins at the cellular level and is the result of abnormal cells that reproduce rapidly and out of control. It can start in one area of the body (in this case, the lungs) and spread (or metastasize) to other organs or the bones.
Primary lung cancer refers to cancer that starts in the lungs, of which there are two main types: non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC). Named initially for how the cancer cells look under the microscope, these two types account for most of the 230,000 newly diagnosed cases of lung cancer in the U.S. each year.
Smokers tend to get a type of NSCLC called squamous cell (which accounts for more than half of lung cancers diagnosed in smokers). Most nonsmokers, on the other hand, are diagnosed with a different non-small cell type known as adenocarcinoma.
How is cancer in nonsmokers different than smoker’s cancer?
Adenocarcinoma, the most common lung cancer diagnosed in nonsmokers, often starts in the outer areas of the lungs, in mucus-producing cells that line the small airways, called bronchioles. Adenocarcinoma has a different shape than other types of lung
cancer, says Daniel Boffa, MD, a Yale Medicine thoracic surgeon.
He offers a helpful way to visualize the difference between the two: “If you are a smoker, you can think of your lung as a bag
of white marbles, and cancer is like putting a black marble in there. The type of cancer a nonsmoker gets is more like putting in black sand. Instead of a spot or a lump, it’s more like a hazy area. It’s more diffuse.”
Another difference is that cancers in nonsmokers tend to grow more slowly. But while they may be less likely to spread (or metastasize) to other parts of the body, they still can recur, even after successful surgery.
What causes lung cancers in nonsmokers?
There may not be a single cause behind a particular case of lung cancer in a nonsmoker—rather, there is often a combination of factors contributing to the disease, says Dr. Boffa.
One of the strongest predictors can be a genetic mutation in the tumor, also known
as a “somatic” mutation, that drives the development of cancer. This is different that
a “germline” mutation, that is present in all
of your normal DNA. Numerous studies have shown that such somatic mutations or abnormalities can play a key role in the development of lung cancer, especially in nonsmokers.
Beyond that, the American Cancer Society lists the following environmental risk factors that may contribute to a diagnosis of lung cancer in a nonsmoker:
Radon gas: Exposure to radon gas is considered to be one of the causes of lung cancer in nonsmokers, accounting for about 21,000 lung cancer deaths each year. Radon is invisible and doesn’t have a smell, but it