Real-World Outcomes of Chemoradiotherapy for Anal Squamous Cell Carcinoma: Insights from Northeast India

Anal squamous cell carcinoma (SCC) is a rare malignancy with rising incidence rates. While chemoradiotherapy (CCRT) has become the standard of care for nonmetastatic anal SCC, there is limited data on treatment outcomes from India, particularly the Northeastern region. This study aims to evaluate the clinical characteristics, treatment outcomes, and toxicity profiles of definitive CCRT for anal SCC at a tertiary cancer center in Northeast India. A retrospective, single-center study was conducted on 22 patients diagnosed with nonmetastatic anal SCC who received definitive CCRT between 2017 and 2021. Radiotherapy was delivered using 3D-CRT, IMRT, or VMAT, with concurrent chemotherapy comprising Mitomycin C (MMC) and 5-fluorouracil (5-FU). Acute and late toxicities were assessed, and survival outcomes were analyzed using the Kaplan-Meier method. The median age of the cohort was 54 years, with a male predominance (64%). The majority of patients had Stage III disease, and the most common symptoms were perianal pain and rectal bleeding. The median overall survival (OS) was 46 months, with 1-year, 2-year, and 3-year OS rates of 95.7%, 78.3%, and 63.6%, respectively. The 3-year locoregional control (LRC) and colostomy-free survival (CFS) rates were 57% and 60%, respectively. Patients receiving ≥ 54 Gy had significantly better survival outcomes. Common acute toxicities experienced included dermatitis, anemia, and neutropenia. Late toxicities were mild, with no grade 3 or 4 late effects observed. CCRT with 5-FU and MMC remains the gold standard for nonmetastatic anal SCC, offering favorable survival outcomes and preserving sphincter function. Advanced radiation techniques like IMRT and VMAT help minimize toxicity. These findings align with both regional and international studies, though further studies are essential to optimize radiation dose regimens and explore novel therapies to further improve patient outcomes.