International Head and Neck Cancer Epidemiology Consortium: Update No. 22.

Background. Cigarette smoking is a major risk factor for head and neck cancer. To our knowledge, low cigarette smoking (<10 cigarettes per day) has not been extensively investigated in fine categories or among never alcohol drinkers. Methods. We conducted a pooled analysis of individual participant data from 23 independent case-control studies, including 19,660 patients with head and neck cancer and 25,566 controls. After exclusion of subjects using other tobacco products, including cigars, pipes, snuffed or chewed tobacco, and straw cigarettes (tobacco product used in Brazil), as well as subjects smoking more than 10 cigarettes per day, 4093 patients with head and neck cancer and 13,416 controls were included in the analysis. The lifetime average frequency of cigarette consumption was categorized as follows: never cigarette users,> 0 to 3,> 3 to 5, and >5 to 10 cigarettes per day. HEAD & NECK—DOI 10.1002/HED OCTOBER 2016 1447 Results. Smoking> 0 to 3 cigarettes per day was associated with a 50% increased risk of head and neck cancer in the study population (odds ratio [OR]5 1.52; 95% confidence interval [CI]5 1.21–1.90). Smoking> 3 to 5 cigarettes per day was associated in each subgroup from OR5 2.01 (95% CI5 1.22–3.31) among never alcohol drinkers to OR5 2.74 (95% CI5 2.01–3.74) among women and in each cancer site, particularly laryngeal cancer (OR5 3.48; 95% CI5 2.40–5.05). However, the observed increased risk of head and neck cancer for low smoking frequency was not found among smokers with smoking duration shorter than 20 years. Conclusion. Our results suggest a public health message that low frequency of cigarette consumption contributes to the development of head and neck cancer. However, smoking duration seems to play at least an equal or a stronger role in the development of head and neck cancer. 1448 HEAD & NECK—DOI 10.1002/HED OCTOBER 2016