PHASE II DOUBLE-BLIND CHEMOPREVENTION TRIAL OF HIGH DOSE FOLIC ACID VERSUS PLACEBO IN PATIENTS WITH RESECTED COLORECTAL POLYPS

Date de début de l'étude : 12 juin 1995

DISEASE CHARACTERISTICS: Colonic adenoma(s) of at least 10 mm completely resected within 18 months prior to randomization or suspected adenomatous polyp(s) Colonoscopy with submission of at least 7 rectosigmoid biopsies required at entry No benign hyperplastic polyps or polyps less than 10 mm to be eligible for treatment No polyposis coli (i.e., more than 100 polyps in colon) No history of invasive colorectal cancer PATIENT CHARACTERISTICS: Age: 21 and over Performance status: ECOG 0-2 Life expectancy: Not specified Hematopoietic: Platelet count greater than 100,000/mm3 Hemoglobin greater than 10 g/dL No untreated pernicious anemia Hepatic: Bilirubin less than 2 mg/dL ALT less than 2 times normal Alkaline phosphatase less than 2 times normal PT normal Renal: Not specified Gastrointestinal: No intestinal malabsorption No inflammatory bowel disease Other: No seizure within the past year No poor medical risk No other malignancy within past 5 years except basal cell cancer, superficial skin cancer, or carcinoma in situ of the cervix No vitamin B12 deficiency (less than 200 pg/mL) Not pregnant or nursing Fertile patients must use effective barrier contraception PRIOR CONCURRENT THERAPY: Biologic therapy: Not specified Chemotherapy: No concurrent methotrexate Endocrine therapy: Not specified Radiotherapy: Not specified Surgery: See Disease Characteristics No prior small bowel resection Other: No concurrent anticonvulsants No concurrent drugs that markedly interfere with folate absorption or metabolism (e.g., sulfasalazine and phenytoin) No concurrent vitamins during and for 2 years after beginning of study