No relations between breast cancer risk and fatty acids of erythrocyte membranes in postmenopausal women of the Malmo Diet Cancer cohort (Sweden)

Objective: To examine the fatty acid composition of erythrocyte membranes, in relation to obesity indexes and breast cancer risk. Design: A nested case-control study. Setting: The Malmo Diet Cancer cohort, Sweden. Subjects: Among women 50 y or older at baseline (n=12803), incident breast cancer cases (n=237) were matched to controls (n=673) on age and screening date. Methods: A diet history method, a structured questionnaire, anthropometrics and blood samples provided data. Analysis included partial correlation coefficients between dietary fatty acids (DFA) and fatty acids of erythrocyte membranes (EFA), and Spearman's rank order correlations between EFA and four obesity indexes. Conditional logistic regression examined breast cancer risks related to EFA. Results: DFA and EFA from fish and milk, and DFA and EFA linoleic acid, show significant positive associations. Relations are negative between indexes of obesity and milk'' EFA, but positive between indexes of obesity and indexes of delta9- and delta6-desaturase enzyme activity. No significant relations were observed between EFA and breast cancer risk. Conclusions: Similar to other studies, dietary fish and milk fatty acids, and linoleic acid, are related to the corresponding EFA. Breast cancer risk was not significantly related to EFA in this study. However, the findings suggest positive relations between body mass index, body fat per cent and indexes of desaturase activity, and negative relations between central obesity and milk EFA. Sponsorship: The Swedish Cancer Society, the Swedish Medical Research Council, the European Commission, the Swedish Dairy Association and the City of Malmo.