Association of Body Composition With Survival and Locoregional Control of Radiotherapy-Treated Head and Neck Squamous Cell Carcinoma

Abstract

Importance: Major weight loss is common in patients with head and neck squamous cell carcinoma (HNSCC) who undergo radiotherapy (RT). How baseline and posttreatment body composition affects outcome is unknown.

Objective: To determine whether lean body mass before and after RT for HNSCC predicts survival and locoregional control.

Design, setting, and participant: Retrospective study of 2840 patients with pathologically proven HNSCC undergoing curative RT at a single academic cancer referral center from October 1, 2003, to August 31, 2013. One hundred ninety patients had computed tomographic (CT) scans available for analysis of skeletal muscle (SM). The effect of pre-RT and post-RT SM depletion (defined as a CT-measured L3 SM index of less than 52.4 cm2/m2 for men and less than 38.5 cm2/m2 for women) on survival and disease control was evaluated. Final follow-up was completed on September 27, 2014, and data were analyzed from October 1, 2014, to November 29, 2015.

Main outcomes and measures: Primary outcomes were overall and disease-specific survival and locoregional control. Secondary analyses included the influence of pre-RT body mass index (BMI) and interscan weight loss on survival and recurrence.

Results: Among the 2840 consecutive patients who underwent screening, 190 had whole-body positron emission tomography-CT or abdominal CT scans before and after RT and were included for analysis. Of these, 160 (84.2%) were men and 30 (15.8%) were women; their mean (SD) age was 57.7 (9.4) years. Median follow up was 68.6 months. Skeletal muscle depletion was detected in 67 patients (35.3%) before RT and an additional 58 patients (30.5%) after RT. Decreased overall survival was predicted by SM depletion before RT (hazard ratio [HR], 1.92; 95% CI, 1.19-3.11; P = .007) and after RT (HR, 2.03; 95% CI, 1.02-4.24; P = .04). Increased BMI was associated with significantly improved survival (HR per 1-U increase in BMI, 0.91; 95% CI, 0.87-0.96; P < .001). Weight loss without SM depletion did not affect outcomes. Post-RT SM depletion was more substantive in competing multivariate models of mortality risk than weight loss-based metrics (Bayesian information criteria difference, 7.9), but pre-RT BMI demonstrated the greatest prognostic value.

Conclusions and relevance: Diminished SM mass assessed by CT imaging or BMI can predict oncologic outcomes for patients with HNSCC, whereas weight loss after RT initiation does not predict SM loss or survival.

Figure 1. The Effect of Skeletal Muscle (SM) Depletion Before Radiotherapy on Survival and Locoregional Recurrence

Patients with depleted SM on presentation demonstrated decreased overall and disease-specific survival compared with patients with normal SM. We found no difference in locoregional control between these groups. HR indicates hazard ratio.

Figure 2. The Effect of Skeletal Muscle (SM) Depletion After Radiotherapy (RT) on Survival and Locoregional Recurrence

Patients who developed SM depletion after the initiation of RT demonstrated decreased overall survival compared with patients with normal SM. The decrease in disease-specific survival was not significant. Locoregional control was decreased significantly in these patients. HR indicates hazard ratio.

Figure 3. The Effect of Body Mass Index (BMI) on Survival and Locoregional Recurrence

Increasing BMI (calculated as weight in kilograms divided by height in meters squared) on presentation predicted improved overall and disease-specific survival. We found no significant increase in locoregional control associated with increased BMI. Normal weight, overweight, and obesity were defined as BMIs of less than 25.0, 25.0 to 29.9, and 30.0 or greater, respectively. HR indicates hazard ratio.