Clinical and Pathological Response in Rectal Cancer to Total Neoadjuvant Therapy (TNT) Using Long-Course Chemoradiation Therapy (LCCRT)

Abstract

Objective: To evaluate the clinical and pathological response rates to long-course Concurrent Chemoradiation therapy in rectal cancer patients, including the rate of conversion to resectable disease and tumor size reduction. Study Design: Prospective Observational Study. Place and Duration of Study: Department of Radiation Oncology, Combined Military Hospital, Rawalpindi Pakistan, from Sept 2024 to Feb 2025. Methodology: A total of 44 biopsy-proven rectal adenocarcinoma patients received 4 cycles of CAPOX chemotherapy, followed by concurrent chemoradiotherapy (CCRT) with 45 Gy in 25 fractions with an optional 5.4 Gy boost, and oral Capecitabine on radiation days. Post-CCRT evaluation was done 4–6 weeks later using MRI, CT scan, digital rectal examination, and sigmoidoscopy. Clinical response was assessed per RECIST 1.1. Postoperative pathology determined treatment response, and data was recorded on a structured proforma. Data was collected and analyzed using SPSS v.25. Results: Complete clinical response was seen in 16(36.4%) patients, partial response in 21(47.7%) patients. 4(9.1%) showed stable disease and 3(6.8%) of the patients showed progressive disease. Pathological stage was ypT0N0 (pCR; pathological complete response) in 9(20.5%), ypT1–T2N0 in 13(29.5%), and ypT3–T4 and/or N+ in 22(50.0%). Low anterior resection was done in 27(61.4%), and abdominoperineal resection in 17(38.6%), with negative margins in 36(81.8%). Lymph node involvement was negative in 26(59.1%) and positive in 18(40.9%).   Conclusion: TNT with LCCRT is an effective treatment for rectal cancer, producing favorable pathological and clinical responses. A notable pCR rate was achieved, and many patients had complete or partial clinical responses.