Comparison of prognostic value of tumor SUL-peak and SUV-max on pretreatment FDG-PET/CT in patients with HNSCC

Objectives FDG-PET/CT is widely used for initial staging or therapeutic assessment of HNSCC. Its prognostic value has been shown by tumor SUVmax measured at initial staging but without real established cut-off. SUL (lean body mass corrected SUV) peak corresponding to the highest possible mean value of a 1 cm3 spherical VOI positioned within the tumor has been recently defined as the optimal parameter for therapeutic evaluation by PERCIST recommendations but its predictive value of survival has never been studied. The aim of this study was to compare the prognostic interest of SULpeak and SUVmax on pretreatment FDG-PET/CT in patients with HNSCC.

Methods Patients referred to our department to perform FDG-PET/CT at staging of HNSCC were prospectively included in the study. SULpeak and SUVmax were determined on tumor using a semi-automatic quantification tool (Syngo.via software, Siemens®). Different discrete values between 3 and 15 were evaluated with log-rank test to determine the best prognostic cut-off point. Kaplan-Meier methods were used to estimate event free survival (EFS) and overall survival (OS).

Results 80 consecutive patients (70M/10F) (mean +/- sd age; 62.7 +/- 9.1 yo) were included. Mean +/- sd SULpeak and SUVmax were respectively 7.7 +/- 4.7 (median 6.5; range 1.3-22.8) and 9.5 +/- 5.6 (median 8.1; range 1.6-25.5). Mean follow-up +/- sd was 20.9 +/- 13.9 months. For EFS analysis, the lowest p-value was found for a threshold of 7 (p<0.0001) and 8 (p=0.0001) respectively for SULpeak and SUVmax. For 0S analysis, the lowest p-value was found for a threshold of 7 (p<0.0001) and 7 (p=0.0004) respectively for SULpeak and SUVmax. There were respectively a rate of death <24% and <15% in patients with a tumor SULpeak and SUVmax <7.

Conclusions Our results suggest no additional prognostic value of tumor SULpeak in comparison with SUVmax on pretreatment FDG-PET/CT in patients with HNSCC.