Abstract
BACKGROUND: It is known that (18)F-2-fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography ((18)F-FDG PET/CT) makes a significant contribution to other diagnostic methods in determining the response to treatment after neoadjuvant chemoradiotherapy (NCRT). The study aimed to determine whether the tumor maximum standardized uptake values (SUVmax) on (18)F-FDG PET/CT is predictive of overall survival (OS) in patients with rectal cancer after neoadjuvant treatment and to investigate whether the rate of change in SUVmax has a prognostic value. MATERIALS AND METHODS: This retrospective study included 64 rectal cancer patients who underwent (18)F-FDG PET/CT imaging, first for staging and then to assess response to neoadjuvant radiotherapy (NRT). SUVmax1 before and SUVmax2 after treatment were measured from the volume of interest (VOI). To determine the predictive value of (18)F-FDG PET/CT SUVmax parameters for death, the area under the curve (AUC) and cut-off values were calculated using Receiver Operator Characteristic (ROC) analysis. Kaplan-Meier analysis was used to evaluate the effect of SUVmax cut of value on OS. RESULTS: Twenty-five (39%) patients were female and 39 (61%) were male. The median follow-up period was 37.5 months. The mean SUVmax1 and SUVmax2 values were 20.1 ± 9.5 and 7.6 ± 4.8, respectively. OS significantly differed when 8.5 was used as a cut-off for SUVmax2 (p = 006). (18)F-FDG PET/CT metabolic tumor parameters had no significant predictive value for progression-free survival (PFS). CONCLUSION: According to the results of our study, SUVmax2 after neoadjuvant treatment had a significant predictive value for OS in patients with recurrent cancer.