Preoperative intensity-modulated chemoradiotherapy with simultaneous integrated boost in rectal cancer: five-year follow-up results of a phase II study
Background and Purpose
We conducted a phase II study to investigate the feasibility and safety of preoperative intensity-modulated radiotherapy using simultaneous integrated boost (IMRT SIB) to shorten the overall treatment time without dose escalation in locally advanced rectal cancer to improve treatment outcome.
Materials and Methods
Fifty-one patients with operable stage II-III rectal carcinoma were included between January 2014 and January 2015. Fifty patients completed preoperative IMRT treatment with an elective dose of 41.8 Gy and simultaneously delivered 46.2 Gy to T2/T3 and 48.4 Gy to T4 tumour in 22 fractions, with concomitant capecitabine (825mg/m2/12h). Median follow-up was 70 months.
Forty-seven patients completed treatment per protocol. Acute toxicity occurred in 2 (4%) patients. R0 resection was achieved in all but 1 and pathologic complete response (pCR) in 12 (25.5%) patients who had 5-year overall survival (OS), disease-free survival (DFS) and local control (LC) of 91.7%, 100% and 100%, respectively. In the intention-to-treat analysis the type of surgery significantly moderated OS and DFS, while total downstaging and pN were predictive for DFS only. For treatment per protocol 5-year OS, DFS and LC were 80.9% (95% CI 69.7-92.1), 77.1% (95% CI 65.1-89.1) and 95.2% (95% CI 88.7-100), respectively. The proportion of patients with severe late (CTCAE G ≥ 3) gastrointestinal, urinary and sexual toxicity was 15%, 2% and 8% respectively, with one secondary carcinoma.
Preoperative IMRT-SIB without dose escalation is well tolerated, with a low acute toxicity profile, can achieve a high rate of pCR and shows encouraging 5-year LC, DFS and OS.
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