Correlation of body mass index and leptin with tumor size and stage of disease in hormone-dependent postmenopausal breast cancer: preliminary results and therapeutic implications

Obesity is considered the most important risk and prognostic factor for estrogen-dependent breast cancer in postmenopausal women. Adipokines, in particular leptin, are at the center of the etiopathogenetic mechanisms by which obesity and related metabolic disorders influence breast cancer risk and its prognosis. The present prospective observational study aims to investigate the relationship between body mass index (BMI), serum levels of leptin and proinflammatory cytokines, and breast cancer prognostic factors. In the study, 98 postmenopausal and 82 premenopausal patients with ER-positive breast cancer participated. During the same study period, 221 control subjects were simultaneously recruited. Women underwent baseline measurements pre-operatively, before any surgical and systemic treatments. Pathologic characteristics of tumors were abstracted from pathology reports. Leptin and proinflammatory cytokines were assayed in stored fasting blood specimens. In postmenopausal breast cancer patients, BMI, leptin, and interleukin-6 significantly correlated with pathological tumor classification (pT) and TNM stage. Multivariate regression analysis showed that BMI and leptin, but not interleukin-6, were independent predictive variables of pT and TNM stage. Our results seem to suggest a twofold role of leptin in the etiopathogenesis of postmenopausal estrogen-positive breast cancer. Indeed, leptin reflects the total amount of fat mass, which correlates to aromatase activity and subsequent estrogens levels. Further studies are warranted to clarify the role of leptin and interleukin-6 in breast carcinogenesis and identify new therapeutic options, beyond the use of aromatase inhibitors, acting selectively on adipokine-driven pathways.