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 oc…