Octreotide in Preventing Diarrhea in Patients Who Are Undergoing Radiation Therapy to the Pelvis

DISEASE CHARACTERISTICS: Histologically confirmed cancer in the pelvis Plan to receive continuous definitive or adjuvant external-beam radiotherapy to the pelvis or pelvis and para-aortic lymph nodes (total planned dose of 4,500-5,350 cGy) Entire pelvis must be encompassed by planned radiotherapy field (superior border not inferior to the most inferior aspect of sacroiliac joints) Portions of rectum may have special blocking depending on disease site Planned treatment for once-daily radiotherapy 4-5 times a week (planned daily dose 170-210 cGy) No planned split-course radiotherapy No planned interstitial brachytherapy prior to completion of external-beam radiotherapy Planned intracavitary radiotherapy allowed No planned cytotoxic chemotherapy agents concurrently with radiotherapy except fluorouracil with or without leucovorin calcium or cisplatin Entered on study before the third radiotherapy fraction No current or prior metastases beyond pelvic or para-aortic lymph nodes No grade 3 or greater diarrhea, rectal bleeding, or abdominal cramping prior to radiotherapy No incontinence of stool PATIENT CHARACTERISTICS: Age: 18 and over Performance status: ECOG 0-2 Renal: No chronic renal failure Creatinine less than 2 times upper limit of normal (for patients with history of renal disease) Other: Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception No known allergy to octreotide No history of inflammatory bowel disease No other concurrent medical condition that would preclude study participation No history of cholecystitis unless prior cholecystectomy PRIOR CONCURRENT THERAPY: Radiotherapy: See Disease Characteristics No prior radiotherapy to the pelvis Surgery: See Disease Characteristics No prior abdominal-perineal resection, Hartmann procedure, or other surgical procedure resulting in non-functioning rectum