Cigarette Smoking
Beta Carotene

Note: Separate PDQ summaries on Screening for Lung Cancer; Small Cell Lung Cancer Treatment; Non-Small Cell Lung Cancer Treatment and Prevention and Cessation of Cigarette Smoking: Control of Tobacco Use are also available.

Cigarette smoking causes lung cancer and, therefore, smoking avoidance and smoking cessation would result in decreased mortality from primary lung cancers.

Levels of Evidence

3ai: Evidence obtained from well-designed and conducted cohort or case-control analytic studies, preferably from more than one center or research group, that have a cancer mortality endpoint.

4ai: Ecologic (descriptive) studies that have a cancer mortality endpoint.

5: Opinions of respected authorities based on clinical experience or reports of expert committees.

Long-term smoking avoidance results in decreased incidence of second primary lung tumors.

Level of Evidence

3aii: Evidence obtained from well-designed and conducted cohort or case-control analytic studies, preferably from more than one center or research group, that have a cancer incidence endpoint.

Pharmacological doses of beta carotene increase lung cancer incidence and mortality in relatively high-intensity smokers.

Level of Evidence

1a: Evidence obtained from at least one well-designed and conducted randomized controlled trial that has cancer mortality and incidence endpoints.

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