Clinical outcomes of radiation therapy as an alternative to radical surgery for early-stage rectal cancer.

PURPOSE: Total mesorectal excision (TME) is the standard treatment for early rectal cancer, but radiation therapy (RT) with or without chemotherapy may be considered as an alternative organ-preserving option. This study evaluated the oncologic outcomes, patterns of failure, salvage treatment efficacy, and TME-free survival (TME-FS) following RT without radical surgery after local excision or biopsy in selected patients. MATERIALS AND METHODS: We retrospectively analyzed 40 patients with cT1-2N0 rectal adenocarcinoma who received RT after local excision or biopsy without subsequent radical surgery between 2007 and 2023. Indications for RT included clinical T1 disease with high-risk features, clinical T2 disease, or tumors located close to the anal verge. The median RT dose was 50.2 Gy, and 29 patients received chemotherapy. Survival outcomes, recurrence patterns, salvage treatments, toxicities, and TME-FS were assessed. RESULTS: The median follow-up was 38 months. The 5-year overall survival rates were 87.5% for the cT1 group and 85.6% for the cT2 group, and the 5-year cancer-specific survival rate was 100% in both groups. The 5-year recurrence-free survival rates were 79.3% and 62.8%, respectively. Overall, nine patients experienced treatment failure, and four patients ultimately underwent salvage TME. The 5-year TME-FS were 87.5% in the cT1 group and 78.6% in the cT2 group. No grade 2 or higher late toxicities were observed. CONCLUSION: RT without radical surgery may be a feasible treatment option for cT1-2N0 rectal cancer patients who are unsuitable for, or decline, radical surgery. Close surveillance and timely salvage treatment remain essential, particularly for those with cT2 disease.