Breast cancer is the second leading cause of cancer-related deaths in women in most industrialized countries. The incidence of this disease in women in Western countries is approximately five times that in women in developing countries and Japan. In Canada, breast cancer is the most common type of cancer in women, with an age-standardized incidence rate of 103 per 100,000 or 30% of all cancers in women. There is compelling evidence that carotenoids play a role in the etiology of breast cancer. Although research on breast cancer prevention has focused intensively on these micronutrients, the mechanisms involved in their reported cancer-preventing activities are not fully understood. The objective of the current study was to assess the possible association between specific and total carotenoids and breast cancer risk and to evaluate the effect modification by diet-related fatty acids and life-style factors in the development of breast cancer.
A population-based case-control study involving 414 incident cases and 429 controls was conducted in French Canadians in Montreal. Dietary intake was estimated with the use of a validated food-frequency questionnaire in face-to-face interviews. There was no significant association that was apparent between any of the individual or total carotenoids and the risk of breast cancer after adjustment for major underlying determinants of breast cancer. In premenopausal women who ever smoked, an increased risk was related to alpha-carotene. Conversely, a reduced risk was related to beta-carotene in women who never used hormone replacement therapy.
In post-menopausal women, total carotenoids were positively associated with breast cancer risk in those with a high arachidonic acid intake, and inversely associated in those with a high docosahexaenoic acid intake. These findings suggest that the combined high intake of total carotenoids and docosahexaenoic acid, including a diet with a high content of fruit, carotenoid-rich vegetables, and DHA-rich fish may reduce the risk of breast cancer.