Pretreatment metabolic tumor volume on FDG-PET predicts clinical outcome in hypopharyngeal carcinoma receiving chemoradiotherapy

Objectives To evaluate the prognostic value of pretreatment FDG-PET in patients (pts) with hypopharyngeal carcinoma (HPC) receiving chemoradiotherapy (CRT), especially focusing on quantitative parameters.

Methods FDG-PET/CT examinations were performed before concurrent CRT in 30 HPC patients (29 men, 1 women; median age, 67 y.o.). The metabolic tumor volume (MTV), the total leision glycosis (TLG) as well as maximum standardized uptake value (SUVmax) and mean SUV (SUVmean) were calculated for the primary site of HPC on the work station (AW suite ver. 2.0 6.5 1z, GE Healthcare). We defined MTV as the volume that SUV was more than 2.5. TLG was calculated as multiplication of MTV and SUVmean in MTV. Receiver operating characteristic (ROC) analysis was performed to determine the cutoffs to differentiate local complete response (CR) after CRT and to compare the quantitative parameters. Clinical outcomes were assessed using RECIST1.1 and cause-specific survival.

Results MTV ranged from 0.0 to 80.45ml, TLG from 0.0 to 498.79ml, SUVmax from 2.1 to 15.5, and SUVmean from 0.0 to 6.2. ROC analysis revealed pretreatment MTV the best parameter to determine CR after CRT (area under curve, 0.930). A cutoff of MTV 26ml yielded the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of 100%, 89%, 96%, and 100%, respectively. Pts with high (≥26ml) MTVs had significantly worse cause-specific survival (p<0.001) as compared to pts with low (<26ml) MTVs.

Conclusions MTV on pretreatment FDG-PET was demonstrated to be a significant prognostic parameter for treatment response and mortality in HPC receiving CRT