Outcome of intraoperative brachytherapy as a salvage treatment for locally recurrent rectal cancer.

Background: Locally advanced recurrent rectal cancer (RRC) requires a multimodal approach. Intraoperative high-dose-rate brachytherapy (HDR-BT) may reduce the risk of local recurrence. However, the optimal therapeutic regimen remains unclear. The aim of this retrospective monocentric study was to evaluate the toxicity of HDR-BT after resection of RRC.

Methods: Between 2018 and 2022, 17 patients with RRC received resection and HDR-BT. HDR-BT was delivered alone or as an anticipated boost with a median dose of 13 Gy (range 10-13 Gy) using an ¹⁹²iridium microSelectron HDR remote afterloader (Elekta AB, Stockholm, Sweden). All participants were followed for assessment of acute and late adverse events using the Common Terminology Criteria for Adverse Events version 5.0 and the modified Late Effects in Normal Tissues criteria (subjective, objective, management, and analytic; LENT-SOMA) at 3‑ to 6‑month intervals.

Results: A total of 17 patients were treated by HDR-BT with median dose of 13 Gy (range 10-13 Gy). Most patients (47%) had an RRC tumor stage of cT3‑4 N0. At the time of RRC diagnosis, 7 patients (41.2%) had visceral metastases (hepatic, pulmonary, or peritoneal) in the sense of oligometastatic disease. The median interval between primary tumor resection and diagnosis of RRC was 17 months (range 1-65 months). In addition to HDR-BT, 2 patients received long-course chemoradiotherapy (CRT; up to 50.4 Gy in 1.8-Gy fractions) and 2 patients received short-course CRT up to 36 Gy in 2‑Gy fractions. For concomitant CRT, all patients received 5‑fluorouracil (5-FU) or capecitabine. Median follow-up was 13 months (range 1-54). The most common acute grade 1-2 toxicities were pain in 7 patients (41.2%), wound healing disorder in 3 patients (17.6%), and lymphedema in 2 patients (11.8%). Chronic toxicities were similar: grade 1-2 pain in 7 patients (41.2%), wound healing disorder in 3 patients (17.6%), and incontinence in 2 patients (11.8%). No patient experienced a grade ≥3 event.

Conclusion: Reirradiation using HDR-BT is well tolerated with low toxicity. An individualized multimodality approach using HDR-BT in the oligometastatic setting should be evaluated in prospective multi-institutional studies.