RESUMEN
BACKGROUND AND PURPOSE: External Beam Radiotherapy (EBRT) followed by Contact X-ray Brachytherapy (CXB) and vice versa are viable alternatives to surgery for selected rectal cancer patients who have small tumours (≤3 cm). However, the optimal sequence of treatment needs to be established. We compared two approaches using Propensity Score (PS) matching and inverse probability treatment weighting (IPTW) analyses to investigate whether the sequence of treatment affected patient outcomes. MATERIALS AND METHODS: This retrospective analysis (2008-2019) included patients with rectal adenocarcinoma (cT1-3,N0-1,M0, grade 1-2, size ≤ 3 cm) who received both EBRT and CXB, irrespective of treatment sequence. PS matching and IPTW were conducted to balance covariate standardised mean differences between groups. Oncological outcomes and rate of post-treatment rectal bleeding were assessed. RESULTS: Following PS matching and IPTW analyses from 251 eligible patients; 103 starting with EBRT (median follow-up: 37 [IQR:18-56] months) and 148 with CXB (median follow-up: 32 [IQR:16-54] months, a significant improvement in 3-year overall survival (77% vs 85%, p = 0.02, [HR:0.58 (95% CI:0.37-0.91)]) and a higher risk of post-treatment rectal bleeding (grade 1 (26%) and grade 2 (6%)) were found in patients who started with CXB (p = 0.08). No significant differences were observed in local regrowth (18% vs 12%, p = 0.47), distant relapse (10% vs 6%, p = 0.53), 3-year organ preservation rates (70% vs 75%, p = 0.20, [HR:0.66 (95% CI: 0.35-1.26)]), or disease-free survival (78% vs 82%, p = 0.17, [HR: 0.47 (95% CI: 0.16-1.38)]) CONCLUSION: In patients with rectal cancer (≤3 cm), commencing with CXB rather than EBRT, was associated with improved overall survival, but had a higher risk of G1/2 rectal bleeding. No statistically significant differences were observed in other oncological outcomes.
RESUMEN
Purpose: A watch-and-wait approach is an alternative to surgery for rectal cancer patients who have achieved a clinical complete response (cCR) following neoadjuvant (chemo)radiotherapy. However, approximately 25-38% of patients experience subsequent local tumor re-growth that requires salvage surgery. We evaluated the effectiveness of contact X-ray brachytherapy (CXB) as an alternative method of salvage therapy for those patients who were either unfit for or refused surgery. Oncological outcomes, tolerability, and feasibility of subsequent surgery for local treatment failure following CXB were reported. Material and methods: From 2009-2021, all patients treated with CXB as salvage therapy for local rectal cancer re-growth after watch-and-wait approach at our center were analyzed. Results: Contact X-ray brachytherapy as a salvage treatment (range, 90-110 Gy) was offered to 56 patients who experienced tumor re-growth following (chemo)radiation and watch-and-wait protocol. Median age was 76 (IQR = 66-83) years. Most patients (82%) had early-stage re-growth (ycT1/ycT2, ycN0), and 18% had more advanced stages (ycT3/ycT4, ycN0). After a median of 37-month follow-up (IQR = 19-53), 48% of patients who had early-stage re-growth achieved a sustained complete remission after CXB compared with 20% of those who had more advanced tumor stages. Disease-free and overall survivals for the whole cohort were 69% and 100% at 1-year, 51% and 82% at 3-year, and 51% and 65% at 5-years. CXB effectively controlled local re-growth-related symptoms. Mild post-CXB side effects occurred in 18% of cases. All (100%) eight patients who developed further local relapse, and 29% of those who had residual disease post-CXB salvage were successfully managed with subsequent surgery. Conclusions: Contact X-ray brachytherapy offers a new treatment option for patients in this situation whose other therapy options are not suitable for or refused initial surgery. Early local tumor re-growth responded best with minimal treatment-related toxicity and excellent symptom control. Disease-free and overall survival rates were acceptable, and delaying surgical salvage for local re-growth did not compromise patients' eventual long-term outcomes.
