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Lung cancer in never smokers

Heather Wakelee, MD
Section Editor
Rogerio C Lilenbaum, MD, FACP
Deputy Editor
Sadhna R Vora, MD


Lung cancer is the leading cause of cancer death worldwide, causing about 1.6 million deaths per year [1]. Exposure to tobacco smoke is the primary etiologic factor responsible for lung cancer, and its importance is illustrated by the decline in lung cancer incidence and mortality in the United States that has accompanied the decline in smoking [2,3]. (See "Cigarette smoking and other possible risk factors for lung cancer".)

Despite the predominance of tobacco smoking as its presumed etiology, lung cancer is also a significant health problem in those with no history of smoking [4,5]. Emerging information supports the notion that lung cancer in never-smokers is distinct enough from an epidemiologic and biologic standpoint to be considered a separate entity [6-9]. Furthermore, as the numbers of never-smokers in the United States and other countries rise, the issue of lung cancer in this group becomes even more critical.

The epidemiology, risk factors, biologic differences, and potential implications for treatment of lung cancer in never-smokers are reviewed here. General aspects of lung cancer biology and management are discussed elsewhere. (See "Overview of the risk factors, pathology, and clinical manifestations of lung cancer" and "Overview of the initial evaluation, treatment and prognosis of lung cancer" and "Overview of the treatment of advanced non-small cell lung cancer".)


In general, the term “never-smoker” refers to individuals who have smoked fewer than 100 cigarettes in their lifetime. Firm data on the incidence of lung cancer in never-smokers is difficult to ascertain, because most population-based cancer registries, including the National Cancer Institute's Surveillance, Epidemiology and End Results (SEER) database, do not collect patient smoking information. SEER data have been linked with population-based tobacco use information [10,11], but this only allows for estimates of lung cancer in never-smokers within broad geographic areas.

Incidence — Worldwide, lung cancer in never-smokers comprises an estimated 15 to 20 percent of cases in men and over 50 percent in women [12]. There are major geographic differences, particularly in Asia, where 60 to 80 percent of women with the disease are never-smokers [4]. The incidence of small cell lung cancer in never-smokers is exceedingly small [13], and this discussion will therefore focus on non-small cell lung cancer (NSCLC).

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Literature review current through: Dec 2017. | This topic last updated: Jan 12, 2017.
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