Who is at Risk?
Lung cancer risk is largely a function of older age combined with extensive cigarette smoking history. Lung cancer is more common in men than women and in those of lower socioeconomic status. Patterns of lung cancer according to demographic characteristics tend to be strongly correlated with historical patterns of cigarette smoking prevalence. An exception to this is the very high rate of lungcancer in African American men, a group whose very high lung cancer death rate is not explainable simply by historical smoking patterns.[1]
In nonsmokers, important lung cancer risk factors are exposure to secondhand smoke, radon exposure, and occupational exposure to lung carcinogens, such as asbestos. Cigarette smoking often interacts with these other factors. There are several examples, including radon exposure and asbestos exposure, in which the combined exposure to cigarette smoke plus another risk factor results in an increase in risk that is much greater than the sum of the risks associated with each factor alone.
Factors associated with increased risk of lung cancer
Cigarette smoking
Starting with the 1964 Surgeon General's Report and followed by each subsequent Surgeon General's Report that has included a review of the evidence on smoking and lung cancer, an enormous body of scientific evidence clearly documents that cigarette smoking causes lung cancer, and that cigarette smoking is the major cause of lung cancer.
Based on solid evidence, cigarette smoking causes lung cancer. The risks of lung cancer associated with cigarette smoking are dose-dependent and increase markedly according to the number of cigarettes smoked per day and the number of years smoked. On average, current smokers have approximately 20 times the risk of lung cancer compared with nonsmokers.
Magnitude of Effect: Increased risk, very large.
| Study Design: Numerous prospective cohort and case-control studies, combined with quasi-experimental evidence showing population-level smoking prevalence predicts the population-level burden of lung cancer. |
| Internal Validity: Good. |
| Consistency: Good. |
| External Validity: Good. |