Heterogeneity and progesterone-receptor distribution in endometrial adenocarcinoma.

Objective response to progestin therapy occurs in 30% to 35% of patients with recurrent or metastatic endometrial carcinoma. Measurement of progesterone receptor (PR) in these tumors has been suggested as a method for distinguishing between responders and nonresponders. However, studies on steroid receptor measurements in endometrial carcinoma may be subject to complexities of tumor, tissue, and cellular heterogeneity. The authors provide evidence for the existence of various types of heterogeneity and address the problem of cellular heterogeneity by determination of PR concentrations in the glandular and stromal cells of the endometrium. It is concluded that until the problem of tumor and tissue heterogeneity is resolved, PR concentrations in endometrial carcinoma must be interpreted with caution.