2Department of Nuclear Medicine, Ege University, Faculty of Medicine, İzmir-Turkey
3Department of Radiology, Ege University, Faculty of Medicine, İzmir-Turkey DOI : 10.5505/tjo.2019.2164 OBJECTIVE
To determine the prognostic and/or predictive role of 18F-FDG PET/CT parameters, such as SUVmax, SUVmean, Metabolic Tumor Volume (MTV) and Total Lesion Glycolysis (TLG=MTVxSUVmean), for the patients with locally advanced rectal cancer (LARC) treated with neoadjuvant radiotherapy±chemotherapy.
METHODS
Between January 2005 and December 2016, a total of 106 patients with clinical T3-4 and/or N+ rectal
cancer without distant metastasis were included in this study. Correlation between metabolic and
volumetric parameters and tumor characteristics was evaluated. Prognostic factors for overall survival
(OS), local recurrence-free survival (LRFS), and distant metastasis-free survival (DMFS) were
analyzed.
RESULTS
The median follow-up duration for all patients was 39.0 months (range, 6?103 months). Pathologic
complete response (pCR) was defined as the absence of viable cancer cells in the resected specimen
(ypT0N0). pCR was achieved in 17% of all cases (18/106). There was a weak correlation between SUVmax
of primary tumor and MTV ([r]=0.238; p<0.001). However, SUVmax of primary tumor and TLG
were significantly correlated (r=0.538; p<0.001). Neither SUVmax nor SUVmean was affected by patient
and tumor characteristics. Posttreatment extensive stage of disease (p=0.013), absence of concomitant
CT (p=0.012), MTV ≥14.65 cm3 (p=0.008), and TLG ?117.00 (p=0.023) were unfavorable prognostic
factors for OS on multivariate analysis.
CONCLUSION
Although FDG-PET is not a standard imaging modality for the treatment of rectal cancers, a negative
effect of high MTV and TLG on OS was shown in our study. We should consider more intense treatment
approaches for tumors with high MTV and TLG values.