Intake of specific carotenoids and essential fatty acids and breast cancer risk in Montreal, Canada.

BACKGROUND Evidence from previous investigations into the possible role of dietary and serum carotenoid concentrations in the etiology of breast cancer is inconsistent. No study has examined the combined effect of carotenoids and essential fatty acids on the risk of breast cancer. OBJECTIVE The objective 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 lifestyle factors in the development of breast cancer. DESIGN 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. RESULTS No significant association 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 [odds ratio (OR) for the upper relative to the lowest quartiles of intake: 2.40; 95% CI: 0.90, 6.41; P for trend = 0.046]. Conversely, a reduced risk was related to beta-carotene (OR: 0.57; 95% CI: 0.26, 1.24; P for trend = 0.05) in women who never used hormone replacement therapy. In postmenopausal women, total carotenoids were positively associated with breast cancer risk in those with a high arachidonic acid intake (OR: 1.92; 95% CI: 0.93, 3.94; P = 0.028 for trend) and inversely associated in those with a high docosahexaenoic acid intake (OR: 0.52; 95% CI: 0.25, 1.07; P for trend = 0.054). CONCLUSION These findings suggest that the combined high intake of total carotenoids and docosahexaenoic acid may reduce the risk of breast cancer.