Purpose: Leptin and adiponectin are produced by the adipose tissue. Mammographic density (MD) is one of the strongest predictors of breast cancer (BC) and is highly influenced by adiposity. How the interplay between MD, obesity, and obesity-related biomarkers influences BC risk, however, is still unknown, especially in premenopausal women, where adiposity seems to be protective for BC. The aim of the present study was to explore the association between circulating leptin, adiponectin, and their ratio, with MD in Mexican premenopausal women who are part of the large Mexican Teachers' Cohort (MTC).
Methods: A subsample of 2,084 women from the MTC participated in a clinical evaluation. Of them, 574 premenopausal women were randomly selected, from four MD strata. Serum leptin and adiponectin concentrations were measured by immunoassays. Multivariate regression analyses were performed to compare means of MD by quartiles of adipokines and their ratio.
Results: High leptin and leptin/adiponectin ratio levels were significantly associated with lower percentage MD and higher absolute and non-absolute dense tissue areas. High adiponectin levels were significantly associated with lower absolute dense and non-dense tissue areas, but not with percentage MD. After adjustment for BMI, only the associations between percentage MD and absolute non-dense tissue area with leptin remained statistically significant.
Conclusions: Leptin, adiponectin, and their ratio were associated with MD; however, only the positive association with leptin seemed to be independent from overall obesity.
Keywords: Adiponectin; Leptin; Mammographic density; Obesity; Premenopausal women.