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.