RÉSUMÉ
BACKGROUND: Body mass index (BMI) has been associated variably with head and neck cancer outcomes. We evaluated the association between BMI at either diagnosis or at early adulthood head and neck cancer outcomes. METHODS: Patients with invasive head and neck squamous cell cancer at Princess Margaret Cancer Centre in Toronto, Canada, were surveyed on tobacco and alcohol exposure, performance status, comorbidities, and BMI at diagnosis. A subset also had data collected for BMI at early adulthood. RESULTS: With a median follow-up of 2.5 years, in 1279 analyzed patients, being overweight (hazard ratio [HR], 0.55; 95% confidence interval [CI], 0.4-0.8; p = .001) at diagnosis was associated with improved survival when compared with individuals with normal weight. In contrast, underweight patients at diagnosis were associated with a worse outcome (HR, 1.89; 95% CI, 1.2-3.1; p < .01). CONCLUSION: Being underweight at diagnosis was an independent, adverse prognostic factor, whereas being overweight conferred better prognosis. BMI in early adulthood was not associated strongly with head and neck cancer outcomes. © 2017 Wiley Periodicals, Inc. Head Neck 39: 1226-1233, 2017.