Volumetric parameters of 2-deoxy-2-[18F]fluoro-d-glucose positron emission tomography/computed tomography can predict...

The purpose of this study was to investigate the clinical potential of 2-deoxy-2-[18F]fluoro-d-glucose positron emission tomography/computed tomography (FDG PET/CT) to evaluate histopathologic effects of preoperative chemoradiotherapy (CRT) in pancreatic adenocarcinoma, with particular focus on volumetric PET/CT parameters.

This study included 25 patients with pancreatic adenocarcinoma who underwent radical surgery after gemcitabine- and S-1-based preoperative-CRT. The extent of residual tumor was graded using the Evans grading systems, and patients with more than 50% destruction of tumor cells were defined as responder. Peak SUV corrected for lean body mass (SUL_peak), metabolic tumor volume (MTV) with a threshold of SUV=2.0, total lesion glycolysis (TLG) of pre- and post-CRT, and reduction rates of SUL_peak in those parameters were assessed by PET/CT. These parameters were compared using the student's t-test between responder and non-responder. The treatment effect was also assessed by contingency table analysis divided with median value of each parameter using chi-square tests.

Eight patients (32%) showed histopathologic poor response (Evans grade I), 11 cases (44%) had mild response (Evans grade IIa), and six cases (24%) had moderate response (Evans grade IIb); therefore, six cases (24%) were assigned to responders and others 19 cases (76%) were non-responders. With regards to volumetric PET parameters, post-CRT SUL_peak of responders was significantly lower than that of non-responders (p=0.013). Post-CRT MTV and TLG were negative for all six cases of responders. There were significant differences between responder and non-responder on the contingency table analysis of post-CRT MTV and TLG status (p=0.014 for both).

This study demonstrated that the volumetric PET/CT parameters, higher post-treatment SUL_peak and positive MTV/TLG could predict the unfavorable histopathological effects of CRT in patients with pancreatic adenocarcinoma.