Relationship of serum isoflavone, insulin and adiponectin levels with breast cancer risk

Abstract

Obesity is one of the well-known risk factors of breast cancer. Accumulating evidence suggests that adiponectin, an obesity-related hormone, is inversely associated with breast cancer risk, particularly in postmenopausal women. Obesity is also associated with high levels of insulin. In addition, studies have suggested that the soy isoflavones present in the traditional Japanese diet have been associated with decreased risk of breast cancer. However, there is no study that has assessed associations between serum levels of isoflavones, insulin, adiponectin and the risk of breast cancer all together with menopausal status. In a case-control study of 63 histologically confirmed breast cancer patients and 76 controls, serum isoflavone, insulin, and high-molecular-weight (HMW) adiponectin levels and breast cancer risk were examined for their association with breast cancer risk after adjustment for various risk factors. Women in the highest tertile of serum HMW adiponectin levels were associated with a statistically significant decreased risk for breast cancer compared with women in the lowest tertile [odds ratio (OR), 0.09; 95% confidence interval (CI) 0.03-0.33]. This association was observed in postmenopausal women (OR 0.06; 95% CI 0.01-0.28), but not in premenopausal women. The observed associations were independent of possible effects of insulin, body mass index, and known risk factors for breast cancer. Serum isoflavones and insulin levels were not associated with breast cancer risk. This study suggests that high serumHMW adiponectin levels are significantly associated with a decreased risk for breast cancer. Our result support the hypothesis that serum adiponectin may act as a potential biomarker for breast cancer.