Same name, different lung cancer

JOHNS HOPKINS (US)—Lung cancer in patients who have never smoked is a very different disease than the lung cancer smokers get, and should be treated as such, new research finds.

“It is becoming increasingly clear that the genetic, cellular, and molecular nature of lung cancer in many never-smokers is different from that of smoking-related lung cancers, and there is good evidence now that the best treatment and prevention strategies for never-smokers may be different as well,” says Charles Rudin, associate director for clinical research at the Kimmel Cancer Center at Johns Hopkins University.

Never-smokers are defined as people who have smoked fewer than 100 cigarettes in their lifetime.

Lung cancer in these cases usually presents at an advanced stage with non-specific symptoms like a cough and chest pain and is often incorrectly treated as a respiratory illness with antibiotics and asthma medications. Doctors rarely suspect lung cancer since these patients have no smoking history, Rudin adds.

“Patients who never smoked respond better to a certain class of drugs called EGFR inhibitors, because lung cancer in these patients more often contain mutations in the EGFR gene,” Rudin says.

EGFR normally promotes cell growth and development, and when mutated, allows the uncontrolled growth of cells that is the hallmark of cancer.

“There are other examples of success in specifically targeting genetic changes in never-smokers with lung cancer, such as treatments of tumors with alterations in the EML4-ALK gene. A genome-wide association study exclusively on this population could tell us more,” he says.

Lung cancer in never-smokers is the sixth-leading cause of cancer deaths in the United States.

Exposure to second-hand smoke and radon gas are thought to play important roles in causing the disease in never-smokers. But about half of cases of never-smokers with lung cancer cannot be explained by known risk factors, which also include asbestos, indoor wood-burning stoves, and aerosolized oils caused by cooking.

“Besides second-hand smoke and radon exposure, we still have a gap of knowledge in explaining the causes of lung cancer in never-smokers,” says Jonathan Samet, professor and Flora L. Thornton Chair of the Department of Preventive Medicine at the University of Southern California.

Rudin says that lung cancer in never-smokers tends to occur more often in women and in certain populations in East Asia, possibly due to women’s increased exposure to indoor pollutants caused by cooking oils and wood-burning stoves.

Lung cancer in non-smokers accounts for 10 to 15 percent of lung cancer cases in the United States, which amounts to approximately 20,000 Americans annually.  Survival rates are poor for most people with any kind of lung cancer.

The research, which was published as three papers in the Sept. 15 issue of Clinical Cancer Research, was funded by the Flight Attendant Medical Research Institute.

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