Preoperative Intensity-Modulated Chemoradiation Therapy with Simultaneous Integrated Boost: 2-Year Follow-up Results of Phase II Study
Background and Purpose
To investigate the feasibility and safety of experimental fractionation using intensity modulated radiation therapy with a simultaneous integrated boost (IMRT-SIB) to shorten the overall treatment time without dose escalation in preoperative radiochemotherapy of locally advanced rectal cancer.
Materials and Methods
Between January 2014 and November 2015, a total of 51 patients with operable stage II-III rectal adenocarcinoma were treated. The preoperative treatment with IMRT and a pelvic dose of 41.8 Gy and simultaneously delivered 46.2 Gy to T2/3 and 48.4 Gy to T4 tumor in 22 fractions, with standard concomitant capecitabine, was completed in 50 patients out of whom 47 were operated. The median follow-up was 35 months.
The rate of acute toxicity G ≥ 3 was 2.4 %. The total downstaging rate was 89 % and radical resection was achieved in 98 % of patients. Pathologic complete response (pCR) was observed in 25.5 % of patients, with 2-year local control (LC), disease free survival (DFS), and overall survival (OS) of 100% for this patient group. An intention-to-treat analysis revealed pN to be a significant prognostic factor for DFS and OS (0.005 and 0.030, respectively). LC for the entire group was 100 %, and 2-year DFS and OS were 90 % (95 % CI 98.4-81.6) and 92.2 % (95 % CI 99.6-84.7), respectively.
The experimental regime in this study resulted in a high rate of pCR with a low acute toxicity profile. Excellent early results translated into encouraging 2-year LC, DFS, and OS.