Distribution of estradiol and percentage of free testosterone in sera of Japanese women: preoperative breast cancer patients and normal controls.

For the purpose of investigating a possible correlation between the genesis of breast cancer and the serum contents of free (non-protein-bound) estradiol (E2) and free testosterone (T) in Japanese women, the distributions of free and total E2 and T and the binding capacity of sex hormone-binding globulin (SHBG) in serum were compared for 39 patients with preoperative breast cancer and 40 normal women (controls). The patients were found to have significantly higher free E2 and free T (in terms of the percentage of the total) than did controls. Conversely, percentages of SHBG-bound E2 and albumin-bound E2 were not significantly different for patients and controls. The SHBG binding capacity was significantly smaller in postmenopausal, but not in premenopausal, patients. Free E2 and free T were found to be negatively correlated with the SHBG binding capacity in both patients and controls. A significant negative correlation also was noted between the percentage of free E2 or free T and the age of controls. The percentage of free T was positively correlated with body weight for both premenopausal and postmenopausal patients. These results suggest a possibility that the elevation of free E2 in the serum may be one of the potential risk factors for genesis of breast cancer in Japanese women.