Postradiation Metabolic Tumor Volume Predicts Outcome in Head-and-Neck Cancer

Purpose To explore the prognostic value of metabolic tumor volume measured on postradiation18 F-fluorodeoxyglucose positron emission tomography (PET) imaging in patients with head-and-neck cancer. Methods and Materials Forty-seven patients with head-and-neck cancer who received pretreatment and posttreatment PET/computed tomography (CT) imaging along with definitive chemoradiotherapy were included in this study. The PET/CT parameters evaluated include the maximum standardized uptake value, metabolic tumor volume (MTV2.0 –MTV4.0 ; where MTV2.0 refers to the volume above a standardized uptake value threshold of 2.0), and integrated tumor volume. Kaplan-Meier and Cox regression models were used to test for association between PET endpoints and disease-free survival and overall survival. Results Multiple postradiation PET endpoints correlated significantly with outcome; however, the most robust predictor of disease progression and death was MTV2.0 . An increase in MTV2.0 of 21cm3 (difference between 75th and 25th percentiles) was associated with an increased risk of disease progression (hazard ratio [HR] = 2.5, p = 0.0001) and death (HR = 2.0, p = 0.003). In patients with nonnasopharyngeal carcinoma histology ( n = 34), MTV2.0