Risk of ovarian carcinoma and consumption of vitamins A, C, and E and specific carotenoids: a prospective analysis.

BACKGROUND

Antioxidant vitamins may decrease risk of cancer by limiting oxidative DNA damage leading to cancer initiation. Few prospective studies have assessed relations between antioxidant vitamins and ovarian carcinoma.

METHODS

The authors prospectively assessed consumption of vitamins A, C, and E and specific carotenoids, as well as fruit and vegetable intake, in relation to ovarian carcinoma risk among 80,326 participants in the Nurses' Health Study who had no history of cancer other than nonmelanoma skin carcinoma. Women reported on known and suspected ovarian carcinoma risk factors including reproductive factors, smoking, and use of vitamin supplements on biennial mailed questionnaires from 1976 to 1996. Food frequency questionnaires were included in 1980, 1984, 1986, and 1990. The authors confirmed 301 incident cases of invasive epithelial ovarian carcinoma during 16 years of dietary follow-up (1980-1996). Pooled logistic regression was used to control for age, oral contraceptive use, body mass index, smoking history, parity, and tubal ligation.

RESULTS

The authors observed no association between ovarian carcinoma risk and antioxidant vitamin consumption from foods, or foods and supplements together. The multivariate relative risks (95% confidence intervals [CIs]) for ovarian carcinoma among women in the highest versus lowest quintile of intake were 1.04 (95% CI, 0.72-1.51) for vitamin A from foods and supplements; 1.01 (95% CI, 0.69-1.47) for vitamin C; 0.88 (95% CI, 0.61-1.27) for vitamin E; and 1.10 (95% CI, 0.76-1.59) for beta-carotene. Among users of vitamin supplements, the authors found no evidence of an association between dose or duration of any specific vitamin and ovarian carcinoma risk, although the authors had limited power to assess these relations. No specific fruits or vegetables were associated significantly with ovarian carcinoma risk. The authors found no association between ovarian carcinoma and consumption of total fruits or vegetables, or specific subgroups including cruciferous vegetables, green leafy vegetables, legumes, or citrus fruits. Women who consumed at least 2.5 total servings of fruits and vegetables as adolescents had a 46% reduction in ovarian carcinoma risk (relative risk, 0.54, 95% CI, 0.29-1.03; P value for trend 0.04).

CONCLUSIONS

These data do not support an important relation between consumption of antioxidant vitamins from foods or supplements, or intake of fruits and vegetables, and incidence of ovarian carcinoma in this cohort. However, modest associations cannot be excluded, and the authors' finding of an inverse association for total fruit and vegetable intake during adolescence raises the possibility that the pertinent exposure period may be much earlier than formerly anticipated.