Metabolic tumour volume as a prognostic factor for oral cavity squamous cell carcinoma treated with primary surgery

Metabolic tumour volume (MTV) obtained from pre-treatment 18 F-fluorodeoxydeglucose positron emission tomography with computed tomography (PET-CT) has been validated as an independent predictive factor of outcomes in head and neck cancer patients (HNC) treated with primary chemoradiotherapy (CRT). However its role in patients treated with primary surgery has not yet been studied. To evaluate the prognostic value of MTV in patients treated with primary surgery for oral cavity squamous cell carcinoma (OCSCC). Demographic and survival data was obtained from patients diagnosed with OCSCC from 2008-2012 in Alberta, Canada. All patients included in the study had PET-CT scan before curative surgical resection. MTV and maximum standardized uptake value (SUVmax) value was delineated from pre-treatment PET-CT scans using Segami Oasis software (Columbus, OH). MTV and SUVmax were divided into intertertile thirds before statistical analysis to allow for in-group comparison of survival. A total of 80 patients were analyzed using SPSS ver. 20.0 (SPSS Inc, Chicago, IL). Five-year overall, and disease-free survival using Kaplan-Meier curves were 70% and 73% respectively. When the combined SUVmax (tumour primary and locoregional metastasis) was evaluated, it failed to predict overall (HR = 1.0, p = 0.99) or disease-free survival (HR = 1.0, p = 0.227). Conversely an increase in MTV of 17.5 mL (difference between the highest and lowest MTV tertile) was associated with a 12.4 fold increase in risk of disease recurrence (p < 0.001) and an 11.2 fold increase in the risk of death (p < 0.05). This study shows that MTV is an independent adverse prognostic factor for death and disease recurrence in OCSCC treated with primary surgery.