Tobacco smoking, smoking cessation, and cumulative risk of upper aerodigestive tract cancers.

Upper aerodigestive tract cancers are strongly related to smoking, and their incidence is substantially lower in former smokers than in continuing smokers. To estimate the effect of smoking cessation on the cumulative incidence of these cancers by age 75 years (in the absence of competing causes of death), the authors combined odds ratios for males from a network of Italian hospital-based case-control studies (1984-2000) with 1993-1997 incidence data for Italian men. The studies included 961 cases with oral/pharyngeal cancer, 618 cases with esophageal cancer, and 613 cases with laryngeal cancer, plus 3,781 controls. For all upper aerodigestive tract cancers, the cumulative risks by 75 years of age were 6.3% for men who continued to smoke any type of tobacco, 3.1% and 1.2% for men who stopped smoking at around 50 and 30 years of age, respectively, and 0.8% among lifelong nonsmokers. Corresponding figures were 3.3%, 1.4%, 0.5%, and 0.2% for oral/pharyngeal cancer; 1.0%, 0.5%, 0.4%, and 0.2% for esophageal cancer; and 2.1%, 1.1%, 0.2%, and 0.2% for laryngeal cancer. In this Italian population, men who stopped smoking before age 50 years avoided more than half of the excess risk of upper aerodigestive tract cancer as men who did not, and men who stopped smoking before age 30 years avoided more than 90% of the risk.