Matched pair analysis to evaluate weight loss during radiation therapy for head and neck cancer as a prognostic factor for survival.

Background: One frequent consequence of radiation therapy (RT) for head and neck cancer (HNC) is weight loss (WL). HNC patients reportedly lose about 9% of their weight during treatment, regardless of pre-treatment WL and nutritional support. We investigated whether high WL during RT has an association with overall (OS) and cancer-specific survival (CSS).

Methods: We retrospectively reviewed weight during RT in HNC patients treated at Roswell Park Comprehensive Cancer Center between 2003 and 2017. High WL was defined as greater than or equal to the median WL. Logistic regression analysis was performed to identify predictors for WL during RT. Multivariate Cox regression and Kaplan-Meier analyses were used to estimate survival outcomes. Propensity score matching was performed to obtain balanced matched-pairs and compare survival outcomes.

Results: A total of 843 patients received either definitive (71%) or post-operative (29%) RT. Median follow-up was 53.6 months [interquartile range (IQR) 35.7-88.9]. Median WL was 5.8% (IQR 0.24-10.6) from baseline weight. Patients with high WL had better OS [hazard ratio (HR) 0.75, 95% confidence interval (CI), 0.61-0.93, P=0.01] and CSS (HR 0.71, 95% CI, 0.55-0.93, P=0.01). 258 matched-pairs were analyzed. Median follow-up was 54.8 months (IQR 35.8-90.4). Median OS was 39.2 months (IQR 21.4-75.7) for high WL versus 36.7 months (IQR 14.6-61.7) for low WL cohorts (P=0.047).

Conclusions: Different from previous reports, this study shows that patients with less WL have worse OS. WL during RT may not be a reliable marker for worse prognosis. A better way to evaluate malnutrition in patients undergoing RT is warranted.