GROWTH AND RECURRENCE OF COLORECTAL POLYPS - A DOUBLE-BLIND 3-YEAR INTERVENTION WITH CALCIUM AND ANTIOXIDANTS

Background: Dietary calcium and antioxidants have been suggested as pr otective agents against colorectal cancer. This has been supported by animal experimental studies, case control and cohort studies. Material s and Methods: In a prospective intervention study of colorectal adeno mas, and intermediary stage in colorectal carcinogenesis, 116 polyp-be aring patients received a placebo-controlled daily mixture of beta-car otene 15 mg, vitamin C 150 mg, vitamin E 75 mg, selenium 101 mu g, and calcium (1.6 g daily) as carbonate for a period of 3 years with annua l colonoscopic follow-up to test if the mixture was able to reduce pol yp growth or recurrence. All polyps of <10 mm at enrolment or follow-u p were left unresected until the end of the study. Results: 87-91% of the patients attended the annual endoscopic follow-up investigations: and 19% of the patients dropped out of the medical intervention. The r est consumed 85% of the total amount of tablets over the 3 years. The fecal calcium concentration was 2.3-2.7 times higher in patients takin g active medication compared to the placebo group. Diet registration s howed that, when adding the intake of antioxidants and calcium from di et and intervention, there was a significant difference between the in take of these substances in the active and the placebo group. No diffe rence was detected in the growth of adenomas between the active and th e placebo group from year to year and for the total study period. More over, there was no effect on polyps of <5 or 5-9 mm, Or on polyps in t he different colonic segments analyzed separately. A reduced growth of adenomas was found in patients <60 years of age taking active medicat ion (n = 8) compared to those taking placebo (n = 6 mean difference 2. 3 mm; 95% CI 0.26-4.36). There was a significantly lower number of pat ients free of new adenomas in the placebo group compared to those taki ng active medication as tested by logistic regression and Kaplan-Meier analysis clog-rank test p value 0.035). Subgroup analysis showed that only the group of patients with no family history of colorectal cance r, those with only one adenoma at inclusion, and those <65 years benef itted from the intervention medication. Conclusion: The study did not find an overall effect on polyp growth, Our data, however, may support a protective role of calcium and antioxidants on new adenoma formatio n.