BladdEr Full OR Empty for Pelvic Radiation Therapy

This study is investigating whether having a full or empty bladder during pelvic radiation therapy makes a difference in outcomes and side effects for people being treated for pelvic cancers — including bladder, bowel, or gynecologic cancers. There is currently no agreed-upon standard, so this trial aims to provide clear guidance. **You may be eligible if...** - You are 18 or older - You are scheduled to receive curative radiation therapy for a pelvic cancer (urinary, bowel, or gynecologic) - You agree to follow the study's bladder preparation instructions - You are willing and able to comply with all study procedures **You may NOT be eligible if...** - You are pregnant - Your tumor is directly invading the bladder wall Talk to your doctor to see if this trial is right for you.