ESTRO 2025 - Abstract Book

S1227

Clinical – Lower GI

ESTRO 2025

Results:

The cohort included 65 patients: 24 men (37%) and 41 women (63%) with a mean age of 63±10.6 years. CR was reported in 13 patients (20%), PR in 21 patients (32%), stable disease (SD) in 22 patients (34%), and progression (PD) in 9 patients (14%). ORR was 52.3%. 18F-FDG PET/CT imaging was performed before nCCRT in 54 patients. Mann Whitney test revealed a significant association between the two groups of patients and SUVmax. Patients with SD and PD had significantly higher SUVmax values compared to PR and CR patients (12.79±6.44 vs 9.32±4.41, p=0.034). ROC analyses revealed that, at the optimal cut-off values for SUVmax, the biomarker could significantly and easily distinguish patients with or without response (AUC=.669, 95% CI: 0. 524-0.813, p=0.03) with a sensitivity of 70.8% and a specificity of 50%. Conclusion: Our results indicate that SUVmax values before nCCRT for LARC and their dynamics might be a potential predictive marker of poor response to nCCRT

Keywords: rectum, radiotherapy, SUV

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Eliana La Rocca 1 , Pier Giorgio Esposito 2 , Giulia Volpi 1 , Valentina Zen 3 , Nunzia Luna Valentina Cernusco 1 , Camilla Zecchetto 3 , Alessandro Muraglia 1 , Carlo Cavedon 2 , Michele Pavarana 3