A Phase I dose escalation trial using Intensity-Modulated Radiotherapy with simultaneous integrated boost in Pelvic Chemoradiotherapy for Metastatic Rectal Cancer

Background: In unresectable metastatic rectal cancers, surgery of primary tumor remains highly debated. Pelvic Chemoradiotherapy (CRT) could allow sufficient local control in order to avoid major and sometimes mutilating surgery. Dose escalated CRT increase control. The aim this study was evaluate the feasibility tolerance a with radiation dose escalation using intensity modulated radiotherapy (IMRT) simultaneous integrated boost (SIB), low middle cancers. Methods: This multicenter phase I included six patients treated for synchronous adenocarcinoma two levels. Radiotherapy delivered IMRT SIB. 52.5 Gy (level 1) 56.25 2) gross tumoral volume (GTV), 25 fractions 2.1 2.25 Gy, respectively. High-risk clinical target (CTV) low-risk CTV received respectively 50 45 Concomitant chemotherapy oral capecitabine performed after four cycles mFOLOX6 chemotherapy. dose-limiting toxicity (DLT) defined as requiring interruption more than five consecutive fractions. Results: All full course treatment at scheduled doses. No had acute radiotherapy, therefore no DLT has been reported. ≥3. Concerning late toxicity, three experienced grade 3. progression occurred. Conclusions: GTV possible. schedule needs be evaluated larger study, patients. Trial registration: NCT03634202. Registered 16 August 2018- retrospectively registered, https://www.clinicaltrials.gov/ct2/show/NCT03634202.