Phase 2 Single-Arm Rectal Cancer Brachytherapy for Patients With Low-Lying Residual Adenocarcinoma After Total Neoadjuvant Therapy to Improve Organ Preservation Rates

This study tests whether brachytherapy (internal radiation therapy placed directly inside or near the tumor) can effectively treat remaining rectal cancer after total neoadjuvant therapy (intensive pre-surgery chemotherapy and radiation) in patients whose cancer has not fully disappeared and who would otherwise need extensive surgery. **You may be eligible if...** - You are an adult (18–100 years old) with low-to-mid rectal cancer - You completed total neoadjuvant therapy but still have some remaining tumor (not a complete response) - Without brachytherapy, your surgical options would require an APR (abdominoperineal resection, which creates a permanent colostomy) or a very low bowel reconnection - You are in reasonably good health (ECOG 0–3) **You may NOT be eligible if...** - Your cancer has a mismatch repair deficiency (dMMR) - Your tumor has completely responded to prior treatment - You have other conditions that prevent brachytherapy Talk to your doctor to see if this trial is right for you.