Testosterone and biological characteristics of breast cancers in postmenopausal women.

Androgens are involved in the development of breast cancer, although the mechanisms remain unclear. To further investigate androgens in breast cancer, we examined the relations between serum testosterone and age, body mass index (BMI), tumor size, histologic type, grade, axillary node involvement, estrogen receptor status, progesterone receptor status, and HER2 overexpression in a cross-sectional study of 592 postmenopausal breast cancer patients. Mean testosterone differences according to categories of patient and tumor characteristics were assayed by Fisher's or Kruskall-Wallis test as appropriate; adjusted odds ratios (OR) of having a tumor characteristic by testosterone tertiles were estimated by logistic regression. Testosterone concentrations were significantly higher in women with BMI >or=30 versus BMI <25. ORs of having a tumor >or=2 cm increased significantly with increasing testosterone tertiles, and the association was stronger in women >/=65 years. The OR of having infiltrating ductal carcinoma was significantly higher in the highest compared with the lowest testosterone tertile. ORs of having estrogen receptor- and progesterone receptor-negative versus estrogen receptor- and progesterone receptor-positive tumors decreased significantly with increasing testosterone tertiles. In women >or=70 years, those with high testosterone had a significantly greater OR of HER2-negative cancer than those with low testosterone. These results support previous findings that high-circulating testosterone is a marker of hormone-dependent breast cancer. The age-related differences in the association of testosterone with other disease and patient characteristics suggest that breast cancers in older postmenopausal women differ markedly from those in younger postmenopausal women. The relationship between testosterone and HER2 status in the oldest patients merits further investigation.