Association of Body Mass Index With Outcomes Among Patients With Head and Neck Cancer Treated With Chemoradiotherapy.

Importance: Combined modality therapy, such as chemoradiotherapy, often results in significant morbidity among patients with head and neck cancer. Although the role of body mass index (BMI) varies based on cancer subtypes, its association with treatment response, tumor recurrence, and survival outcomes among patients with head and neck cancer remains unclear. Objective: To evaluate the role of BMI in treatment response, tumor recurrence, and survival outcomes among patients with head and neck cancer undergoing chemoradiotherapy. Design, Setting, and Participants: This retrospective, observational, single-institution cohort study conducted at a comprehensive cancer center included 445 patients with nonmetastatic head and neck cancer who underwent chemoradiotherapy from January 1, 2005, to January 31, 2021. Exposure: Normal vs overweight or obese BMI. Main Outcomes and Measures: Metabolic response after chemoradiotherapy, locoregional failure (LRF), distant failure (DF), overall survival (OS), and progression-free survival (PFS), with Bonferroni correction used to adjust for multiple comparisons and P < .025 being considered statistically significant. Results: A total of 445 patients (373 men [83.8%]; median age, 61 years [IQR, 55-66 years]; 107 [24.0%] with normal BMI, 179 [40.2%] with overweight BMI, and 159 [35.7%] with obese BMI) were included for analysis. Median follow-up was 48.1 months (IQR, 24.7-74.9 months). On Cox proportional hazards regression multivariable analysis, only overweight BMI was associated with improved OS (5-year OS, 71.5% vs 58.4%; adjusted hazard ratio [AHR], 0.59 [95% CI, 0.39-0.91]; P = .02) and PFS (5-year PFS, 68.3% vs 50.8%; AHR, 0.51 [95% CI, 0.34-0.75]; P < .001). On logistic multivariable analysis, overweight BMI (91.6% vs 73.8%; adjusted odds ratio [AOR], 0.86 [95% CI, 0.80-0.93]; P < .001) and obese BMI (90.6% vs 73.8%; AOR, 0.89 [95% CI, 0.81-0.96]; P = .005) were associated with complete metabolic response on follow-up positron emission tomography-computed tomography after treatments. On Fine-Gray multivariable analysis, overweight BMI was associated with reduction in LRF (5-year LRF, 7.0% vs 25.9%; AHR, 0.30 [95% CI, 0.12-0.71]; P = .01), but not DF (5-year DF, 17.4% vs 21.5%; AHR, 0.92 [95% CI, 0.47-1.77]; P = .79). Obese BMI was not associated with LRF (5-year LRF, 10.4% vs 25.9%; AHR, 0.63 [95% CI, 0.29-1.37]; P = .24) or DF (5-year DF, 15.0% vs 21.5%; AHR, 0.70 [95% CI, 0.35-1.38]; P = .30). Conclusion: In this cohort study of patients with head and neck cancer, when compared with normal BMI, overweight BMI was an independent factor favorably associated with complete response after treatments, OS, PFS, and LRF. Further investigations are warranted to improve understanding on the role of BMI among patients with head and neck cancer.