Null Results in Brief Conjugated Linoleic Acid Content in Breast Adipose Tissue Is Not Associated with the Relative Risk of Breast Cancer in a Population of French Patients

Introduction CLA refer to a group of octadecadienoic acid isomers that contain two conjugated double bonds. CLA can be found in natural food sources, such as dairy products or meat of ruminant animals. Considerable attention has been directed recently to CLA based on their ability to act as preventive agents in experimental rat mammary carcinogenesis, irrespective of the type or level of fat present in the diet (1). This suggest that dietary CLA might also be used in humans for chemoprevention of breast cancer. The feasibility of increasing CLA content of food is already being considered to increase CLA intake in humans (2). Despite such a potential, few data are available in humans, likely as a consequence of the difficulty to obtain accurate estimates of dietary CLA intake. One study conducted in Finland examined the relationship between dietary or serum CLA in women and the risk of breast cancer, and found dietary or serum CLA to be significantly lower in cases than in controls, suggesting a protective effect of CLA on breast cancer risk but only in postmenopausal patients (3). Because CLA accumulates in body fat stores, we used the CLA content of breast adipose tissue, obtained at the time of surgery, as a qualitative biomarker of CLA dietary intake, and we conducted a case-control study among 297 women treated for breast cancer or benign breast disease at the University Hospital of Tours, France, to evaluate the hypothesis that CLA protect against breast cancer.