RATIONALE: Drugs such as octreotide and loperamide hydrochloride use different ways to relieve the diarrhea caused by chemotherapy.

PURPOSE: Randomized phase III trial to compare the effectiveness of octreotide with loperamide hydrochloride for the treatment of chemotherapy-related diarrhea in patients who have colorectal cancer.

OBJECTIVES: I. Determine the safety and efficacy of octreotide acetate versus conventional therapy with loperamide hydrochloride for chemotherapy related diarrhea in patients with advanced colorectal malignancies undergoing chemotherapy with fluorouracil or fluorouracil based regimens.

OUTLINE: This is a prospective, randomized, parallel, open label, multicenter study. Patients are stratified by therapy, grade of diarrhea, and prior use of loperamide hydrochloride or octreotide acetate. Patients undergo 1 of 3 treatments. Patients receive either low doses of octreotide (arm A) or high doses of octreotide (arm B) subcutaneously 3 times daily for 5 days. Patients in arm C receive oral doses of loperamide following each unformed stool for 5 days. A diary is completed by patients to record medications and bowel history. Treatment continues if diarrhea persists beyond day 5, but will be considered a treatment failure. If diarrhea continues to worsen, patients are removed from study. All patients are followed for 24 days.

PROJECTED ACCRUAL: This study will accrue a total of 500 patients.

DISEASE CHARACTERISTICS: Histologically confirmed colorectal carcinoma At least grade 2 diarrhea as a consequence of chemotherapy

PATIENT CHARACTERISTICS: Age: 18 and over Performance status: ECOG 0-2 Life expectancy: Not specified Hematopoietic: Not specified Hepatic: Not specified Renal: Not specified Other: Concurrent enrollment into SWOG-9420 protocol allowed No sensitivity to octreotide acetate or loperamide hydrochloride Eligible if less than 24 hours since prior loperamide or octreotide and no resolution of diarrhea Not pregnant or lactating Effective contraception required of fertile patients Not HIV positive No idiopathic ulcerative colitis or Crohn's disease, acute stool culture positive bacterial colitis, pseudomembranous colitis, short bowel syndrome, enteroenteric fistulae, chronic pancreatitis, ischemic bowel disease, or gastrointestinal disorders known to cause diarrhea Absence of definitive culture results required

PRIOR CONCURRENT THERAPY: Biologic therapy: Not specified Chemotherapy: Prior chemotherapy with a fluoropyrimidine alone or in combination with an accepted modulating agent (leucovorin, levamisole, methotrexate, interferon, PALA, or hydroxyurea) required Prior chemotherapy with uracil mustard and tegafur (UFT) allowed No concurrent chemotherapy allowed during study Endocrine therapy: Not specified Radiotherapy: No whole pelvic or abdominal radiation therapy allowed Surgery: No colectomy, coloanal anastamosis, abdominoperineal resection, or colostomy allowed Other: No antidiarrheal agents (e.g., diphenoxylate hydrochloride, elixir paregoric, opium tincture or tincture of belladonna, or kaolin) during study No cyclosporine allowed