No Surgery Trial / Two Dose-escalation Strategies

This trial explores whether some patients with early-stage rectal cancer can avoid surgery altogether by using a combination of internal radiation (brachytherapy) and chemotherapy, comparing two different radiation dosing strategies. **You may be eligible if...** - You are 18 or older with rectal cancer that has been staged as T2 or T3 (cancer that has grown into but not completely through the rectal wall) based on MRI or ultrasound - Your cancer has not spread to lymph nodes or other organs - Your tumor is small (less than 5 cm), located in the lower rectum (within 10 cm of the anal opening), and accessible for internal radiation treatment - You are a good candidate for both brachytherapy (internal radiation) and chemotherapy **You may NOT be eligible if...** - You have previously had radiation to the pelvic area - Your cancer has spread to other parts of the body (metastatic disease) - The cancer extends into the anal canal - Your tumor is classified as T4 (deeply invasive) or is larger than 5 cm Talk to your doctor to see if this trial is right for you.