Organ Preservation First Strategy and Intentional Watch and Wait for MRI Defined Low-risk Rectal Cancer

This study tests whether a watch-and-wait approach (avoiding surgery if the tumor disappears completely after treatment) works safely for patients with low-risk rectal cancer very close to the anal opening. Patients receive radiation and chemotherapy, and those with complete tumor disappearance may avoid major surgery. **You may be eligible if...** - You are between 18 and 85 years old with a confirmed rectal adenocarcinoma - Your tumor is within 4 cm of the anal sphincter on MRI (or within 8 cm by scope) - Your cancer is stage T2, T3a, or T3b without spread to surrounding structures or lymph nodes - The tumor is no larger than 4 cm in diameter - You have no distant spread of cancer **You may NOT be eligible if...** - Your tumor has spread to the tissue surrounding the rectum or nearby lymph nodes outside the mesorectum - You have distant metastases - You have prior pelvic radiation or surgery that would complicate treatment Talk to your doctor to see if this trial is right for you.