Prospective investigation of the cigarette smoking-head and neck cancer association by sex

BACKGROUND. Men are approximately 3 times more likely to develop squamous cancers of the head and neck (oral cavity, pharynx, and larynx) than women. Very few prospective studies have examined the association between cigarette smoking and cancers of the head and neck in women, even though the rates of smoking in women are increasing rapidly worldwide. METHODS. The association between cigarette smoking and head and neck cancer was investigated in 476,211 participants, aged 50-71 years, of the National Institutes of Health/American Association of Retired Persons (NIH-AARP) diet and health study by using age-standardized incidence rates and hazard ratios from Cox models adjusted for other risk factors for these cancers. RESULTS. Over the course of follow-up (1995 through 2000), 584 Dien and 175 women were diagnosed with head and neck cancer. Nonsmoking (24.4), former smoking (36.9), and current smoking (147.3) men had higher rates of incident head and neck cancer per 100,000 person-years of follow-up than women did in each equivalent category of cigarette use (non: 4.8; former: 17.2; current: 75.7). The hazard ratios associated with smoking were significantly larger in women (12.96; 95% confidence interval [CI], 7.81-21.52) than in men (5.45, 95% CI, 4.22-7.05; P for interaction: <.001) for head and neck cancer overall and also for the 3 subsites (oral cavity, oro-hypopharynx, and larynx) examined in stratified analyses. Ever-smoking accounted for 45% of head and neck cancers in men and 75% in women, assuming causality. CONCLUSIONS. Cigarette smoking is a strong risk factor for head and neck cancer in both men and women. Incidence rates of head and neck cancer were higher in male smokers than female smokers, but smoking may explain a higher proportion of head and neck cancer in women than in men.