Complication and response assessment of high-dose-rate endorectal brachytherapy boost in neo-adjuvant chemoradiotherapy of locally advanced rectal cancer with long-term outcomes

Abstract

Purpose: To identify efficacy, complication, and pathologic response of high-dose-rate endorectal brachytherapy (HDR-BRT) boost in neo-adjuvant chemoradiotherapy (nCRT) of locally advanced rectal cancer.Material and methods: Forty-four patients who met eligibility criteria were included in this non-randomized comparative study. Control group was recruited retrospectively. nCRT (50.40 Gy/28 fr. plus capecitabine 825 mg/m 2 twice daily) was administered to both groups before surgery. In the case group, HDR-BRT (8 Gy/2 fr.) was supplemented after chemoradiation. Surgery was done 6-8 weeks after completion of neo-adjuvant therapy. Pathologic complete response (pCR) was the study's primary endpoint.Results: From 44 patients in the case and control groups, pCR was 11 (50%) and 8 (36.4%), respectively (p = 0.27). According to Ryan's grading system, tumor regression grade (TRG) TRG1, TRG2, and TRG3 were 16 (72.7%), 2 (9.1%), and 4 (18.2%) in the case, and 10 (45.5%), 7 (31.8%), and 5 (22.7%) in the control group (p = 0.118). T down-staging was found in 19 (86.4%) and 13 (59.1%) patients in the case and control groups, respectively. No grade > 2 toxicity was identified in both the groups. Organ preservation was achieved in 42.8% and 15.3% in the case and control arm (p = 0.192). In the case group, 8-year overall survival (OS) and disease-free survival (DFS) were 89% (95% CI: 73-100%) and 78% (95% CI: 58-98%), respectively. Our study did not reach median OS and median DFS.Conclusions: Treatment schedule was well-tolerated, and neo-adjuvant HDR-BRT could achieve better T downstaging as a boost comparing with nCRT, without significant complication. However, the optimal dose and fractions in the context of HDR-BRT boost needs further studies.

High‐dose rate endorectal brachytherapy for rectal cancer: A state‐of‐the‐art review

“… 42 For operable LARC patients, using HDR‐ICBT as a boost to the EBRT dose to achieve a better response rate is a widely used approach. Previous studies have shown that dose escalation with HDR‐ICBT results in higher complete response rates 10 , 12 , 14 , 15 and improved downstaging, 10 , 11 with no significant increase in toxicity or surgical complications 9 , 10 , 12 , 14 compared to neoadjuvant CRT alone, and that most of the adverse effects could be controlled medically (Table 2 ). 10 , 11 The T downstaging may be closely associated with improved sphincter retention, 10 , 16 , 17 which would significantly improve patients' quality of life.…”

“… 7 Subsequent studies have reported its advantages in achieving pCR as a neoadjuvant monotherapy in the early stage 8 or as a boost to EBRT in locally advanced rectal cancer (LARC). 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 HDREBT is now widely applied across various stages of rectal cancer and has shown promising results in achieving high complete response rates. HDREBT also has the potential to enable nonoperative management and improve organ preservation rates in selected cases.…”