Progesterone receptor content in endometrial carcinoma correlates with serum levels of free estradiol.

OBJECTIVE. To study a possible relationship between serum levels of estrogens and androgens and the tumor content of estrogen receptors and progesterone receptors in endometrial cancer. STUDY DESIGN. Fifty postmenopausal patients were included. Receptors were determined biochemically in tissue cytosol by dextran charcoal-coated assay and immunohistochemically on frozen sections. Serum sex hormones were measured by radioimmunoassays. MAIN FINDINGS. Tumor biochemical progesterone receptor content correlated positively (p < 0.05) with free estradiol serum levels. No correlations were observed between estrogen receptor content and any of the serum sex hormones. The progesterone/estrogen receptor ratio, calculated from the biochemical values, correlated positively (p < 0.05) with the serum levels of free estradiol. This relation was not affected by tumor histologic grade or stage. Furthermore, this ratio correlated positively with body mass index, probably reflecting a correlation between body mass and serum estrogens. Biochemical and immunohistochemical receptor values were correlated. CONCLUSIONS. These findings suggest that hormonal regulation of receptor levels may remain preserved in at least some endometrial cancer cells.