Vitamin supplements among women with adenomatous polyps and cancer of the colon. Preliminary findings

The effect of calcium and vitamin supplements on the incidence and recurrence of colorectal adenomatous polyps

BACKGROUND

Recent attention has focused on calcium and certain vitamins as potential protective agents against colorectal neoplasia.

METHODS

Two case-control studies were conducted on patients who underwent colonoscopy between 1986 and 1988, comparing 297 patients with newly diagnosed adenomas with 505 controls (without current or prior history of neoplasia), and 198 patients with recurrent adenomas with 347 recurrent controls (with no current neoplasia, but with a history of polypectomy). Subjects were interviewed regarding their regular usage of supplementation with vitamins A, C, D, and E, or with calcium, multivitamins, or any vitamin supplements.

RESULTS

No consistent associations were observed with the use of any of these supplements.

CONCLUSIONS

More studies are necessary to confirm these findings. It may be necessary to develop other chemopreventive agents, such as aspirin, for colorectal neoplasia.

Modulation of colonic aberrant crypt foci and proliferative indexes in colon and prostate glands of rats by vitamin E

The effect of a high vitamin E diet on the early stages of colon carcinogenesis and on the proliferative indexes in the colon and in the prostate glands was investigated in rats. F344 male rats were injected with azoxymethane (AOM, 15 mg/kg sc). One week later, animals were randomly allocated into two dietary groups (n = 8 rats/group): normal vitamin E (50 IU/kg diet) and high vitamin E (200 IU/kg diet). The basal diet was the AIN-76 diet modified to contain high corn oil (23% wt/wt). After eight weeks of feeding, concentrations of vitamin E in plasma, liver, and prostate were analyzed. Enumeration of aberrant crypt foci (ACF) in colons and proliferative indexes of colons and prostate glands were determined. The total number of ACF and the average number of aberrant crypts (AC) per focus were similar in both dietary groups. ACF were classified as small (1-3 crypts/focus), medium (4-6 crypts/focus), or large (> or = 7 crypts/focus). Only the ACF in the small category showed a significant treatment effect, with values being lower in the high vitamin E group than in the control group (p < or = 0.05). No significant difference was observed in colonic proliferative indexes assessed by enumeration of metaphase cells, S phase cells, or cells exhibiting proliferative cell nuclear antigen (PCNA). The PCNA labeling index in the prostate glands and the activity of prostatic acid phosphatase in plasma were higher in high vitamin E-fed rats (p < or = 0.05) than in control animals. The present study demonstrates that additional vitamin E does not inhibit the induction and growth of ACF; also it enhances the proliferative status of the prostate glands.

Dietary risk factors for cancer and adenomas of the large intestine. A case-control study within a screening trial in Denmark

The aims of the study were to estimate the importance of dietary habits for colorectal cancers and adenomas. By comparing risk factors among cancer and adenoma patients the adenoma cancer theory was indirectly evaluated. The study was performed as a case-control study within a large screening trial in Denmark. All cancer and adenoma patients diagnosed at the screening were recruited as cases; controls were selected among test negatives after matching for age, sex and time of screening. All those selected except 85, participated in a 7-day dietary recall. Altogether 49 colorectal cancer patients and 172 with adenomas were examined; 362 individuals who were test negatives in the Hemoccult-II screen served as controls. The intake of crude dietary fibres was shown to be associated with reduced risk of cancer as well as adenomas. Neither cancer nor adenoma occurrences were related to total energy intake or body mass. Vitamins E and A were negatively associated with adenoma occurrence.

Colorectal adenomas and diet: a case-control study of subjects participating in the Nottingham faecal occult blood screening programme

Diets high in animal fat and protein and low in fibre and calcium are thought to be factors in the etiology of colorectal cancer. Intakes of these nutrients were determined in three groups participating in a randomised trial of faecal occult blood (FOB) screening. A diet history was obtained by interview from 147 patients with colorectal adenomas, 153 age and sex matched FOB-negative controls (a) and 176 FOB-positive controls without colorectal neoplasia (b). Unconditional logistic regression was used to estimate relative risks (RR) and 95% confidence limits (increases) adjusted for age, sex and social class. After adjustment for total energy intake, no associations were found with total, saturated or mono-unsaturated fat, or calcium intake. For total fibre intake there were non-linear relationships with both control groups with the crude RR for highest quintiles of total fibre intake compared to the lowest being 0.6, although this pattern was no longer apparent after adjustment for energy intake with group (a). In comparison with group (b) cereal fibre intake showed a more consistent inverse relationship with adenoma prevalence with the RR for ascending quintiles of intake being 1.0, 0.7 (0.3-1.6), 0.5 (0.3-1.1), 0.7 (0.4-1.4) and 0.3 (0.1-0.6) (trend chi 2 = 8.80, p = 0.003). In comparison with group (a), the adjusted RR for the highest quintile of cereal fibre intake compared with the lowest was 0.6, but no clear trend was apparent. There was an unexpected positive relationship between adenomas and polyunsaturated fat intake with the RR for having an adenoma being 1.0, 2.8 (1.3-6.1), 1.6 (0.7-3.4), 3.5 (1.6-7.5) and 2.3 (1.1-5.0) for ascending quintiles of polyunsaturated fat intakes (trend chi 2 = 4.8, P = 0.03) in comparison with group (a) only. Our data, while providing no support for the role of dietary animal fat or protein, do support the protective role of dietary cereal fibre in the etiology of colorectal adenomas.

Intervention studies in adenoma patients

There is considerable evidence that most colorectal carcinomas arise in preexisting adenomas. It also appears that there may be a considerable influence of diet in the genesis and growth of adenomas. This evidence is discussed and the current dietary intervention studies in humans are reviewed.