POSTRADIATION METABOLIC TUMOR VOLUME PREDICTS OUTCOME IN HEAD-AND-NECK CANCER

Purpose: To explore the prognostic value of metabolic tumor volume measured on postradiation F-18-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 post-treatment 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 21cm(3) (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 <18 cm(3) and MTV2.0 >= 18 cm(3) yielded 2-year disease-free survival rates of 100% and 63%, respectively (p = 0.006) and 2-year overall survival rates of 100% and 81%, respectively (p = 0.009). There was no correlation between MTV2.0 and disease-free survival or overall survival with nasopharyngeal carcinoma histology (n = 13). On multivariate analysis, only postradiation MTV2.0 was predictive of disease-free survival (HR = 2.47, p = 0.0001) and overall survival (HR = 1.98,p = 0.003). Conclusions: Postradiation metabolic tumor volume is an adverse prognostic factor in head-and-neck cancer. Biomarkers such as MTV are important for risk stratification and will be valuable in the future with risk-adapted therapies. (C) 2011 Elsevier Inc.