Abstract
Purpose:To investigate the prognostic effects of baseline volumetric PET/CT parameters including the maximum standard uptake value(SUVmax), metabolic tumor volume(MTV), and tumor lesion glycolysis(TLG) on treatment response and prognosis in locally-advanced rectal cancer(LARC) treated with neoadjuvant chemoradiotherapy(NACRT).Methods:Between 2015 and 2018, 51 patients with LARC treated with NACRT followed by surgery were included in this retrospective study. Patients were divided into 2 groups by tumor regression grade(TRG) as follows;Group I=TRG 1(No detectable cancer cells)+TRG 2(single cells and/or small groups of cancer cells) and Group II=TRG3(residual tumor outgrown by fibrosis)+TRG 4(remarkable fibrosis outgrown by tumor cells)+TRG 5(No fibrosis with extensive residual cancer).Results:Of the 51 patients, 34(66.7%) were male. The median age was 55(range,37-78) years. According to TRG status, 14(27.4%) patients were in group I and 37(72.6%) patients were in group II. The area under the curve(95% CI) was 0.749(0.593-0.905) in the ROC curve plotted for MTV. The cut of value for MTV was 12, with 70% sensitivity and 65% specificity. MTV was≥12 in 32(62.8%) patients. MTV and TLG values were significantly different between Group I and II, whereas there was no significant difference between the groups in terms of SUVmax values (p=0.006, p=0.033, and p=0.673, respectively). The disease-free survival was not reached in patients with MTV<12 vs. 20 months in those with MTV≥12 (p=0.323). In multivariate analysis, MTV(OR, 95% Cl, 5.00[1.17-21.383]) was found to be the factor that affected pathological complete response.Conclusion:In LARC treated with NACRT, MTV prior to treatment can help predict the response to treatment.
The Predictive Value of Baseline Volumetric PET/CT Parameters on Treatment Response and Prognosis in Locally Advanced Rectal Cancer Treated with Neoadjuvant Chemoradiotherapy
