Background: While external factors are responsible for many human cancers, precise estimates of the contribution of known carcinogens to the cancer burden in a given population have been scarce.
Methods: We estimated the proportion of cancer deaths which occurred in France in 2000 attributable to known risk factors, based on data on frequency of exposure around 1985.
Results: In 2000, tobacco smoking was responsible for 23.9% of cancer deaths (33.4% in men and 9.6% in women), alcohol drinking for 6.9% (9.4% in men and 3.0% in women) and chronic infections for 3.7%. Occupation is responsible for 3.7% of cancer deaths in men; lack of physical activity, overweight/obesity and use of exogenous hormones are responsible for 2%-3% of cancer deaths in women. Other risk factors, including pollutants, are responsible for <1% of cancer deaths. Thus, known risk factors explain 35.0% of cancer deaths, and 15.0% among never smokers.
Conclusions: While cancer mortality is decreasing in France, known risk factors of cancer explain only a minority of cancers, with a predominant role of tobacco smoking.