A PROSPECTIVE-STUDY OF ASSOCIATION OF MONOUNSATURATED FAT AND OTHER TYPES OF FAT WITH RISK OF BREAST-CANCER

Background: Animal studies suggest that monounsaturated and polyunsatu rated fat may have opposite effects on the risk of breast cancer. Meth ods: We performed a population-based prospective cohort study, includi ng 61471 women aged 40 to 76 years from 2 counties in central Sweden w ho did not have any previous diagnosis of cancer; 674 cases of invasiv e breast cancer occurred during an average follow-up of 4.2 years. All subjects answered a validated 67-item food frequency questionnaire at baseline. Cox proportional hat ards models were used to obtain adjust ed rate ratio (RR) estimates with 95% confidence intervals (CIs). Resu lts: After mutual adjustment of different types of far, an inverse ass ociation with monounsaturated fat and a positive association with poly unsaturated fat were found. The RR for each 10-g increment in daily in take of monounsaturated fat was 0.45 (95% CI, 0.22-0.95), whereas the RR for a S-g increment of polyunsaturated fat was 1.69 (95% CI, 1.02-2 .78); the increments correspond to approximately 2 SDs of intake in th e population. Comparing the highest quartile of intake with the lowest , we found an RR of 0.8 (95% CI, 0.5-1.2) for monounsaturated fat and 1.2 (95% CI. 0.9-1.6) for polyunsaturated fat. Saturated fat was not a ssociated with the risk of breast cancer. Conclusions: Our results ind icate that various types of fat may have: specific opposite effects on the risk of breast cancer that closely resemble the corresponding eff ects in experimental animals. Research investigations and health polic y considerations should take into account the emerging evidence that m onounsaturated fat might be protective for risk of breast cancer.