Prospective studies of body mass index with head and neck cancer incidence and mortality.

Background: Results of a pooled analysis of case-control studies show a higher risk of head and neck cancer (HNC) associated with a low body mass index (BMI) and a lower risk associated with being overweight or obese compared with being normal weight. However, these results are prone to bias due to residual confounding by smoking, a strong risk factor, and possible weight loss prior to diagnosis. Using prospectively collected data from the Cancer Prevention Study-II cohort and the Nutrition cohort, we examined the association of BMI with HNC mortality and incidence, overall and by smoking status.

Methods: Mortality analyses included 1,383 cases among 1,059,153 participants; incidence analyses included 340 cases among 150,262 participants. Multivariable Cox proportional hazard models were used to estimate HRs and 95% confidence intervals (CI) for the association of BMI with HNC incidence and mortality.

Results: Overall, compared with the category of BMI 22.5-24.9 kg/m(2), the categories of BMI 25.0-29.9 kg/m(2) and ≥ 30.0 kg/m(2) were associated with a lower risk of HNC mortality but not incidence. In never smokers, there were no associations of BMI with HNC incidence or mortality. In smokers, BMI < 22.5 kg/m(2) was associated with a higher risk of HNC mortality (HR = 1.42, 95% CI, 1.20-1.67).

Conclusions: In this prospective cohort, there was no association between BMI and HNC incidence, although BMI was inversely associated with HNC mortality in smokers.

Impact: These suggest that there is no etiologic relationship between BMI and HNC.