Endometrial adenocarcinoma estrogen receptor content: association of clinicopathologic features with immunohistochemical analysis compared with standard biochemical methods.

Endometrial adenocarcinomas from 96 patients were studied for their biochemical estrogen receptor content as well as immunohistochemical localization of estrogen receptor. A well-characterized specific monoclonal antihuman estrogen receptor antibody (H222 sp gamma) as amplified by peroxidase/antiperoxidase techniques was used for immunohistologic localization. Immunohistochemical evaluation incorporated both the intensity and distribution of staining into a semiquantitative analysis (HSCORE). The total HSCORE was the sum of the relative contributions of the four histologic components: benign epithelium, malignant epithelium, stroma, and myometrium. These results were compared with clinicopathologic features of the tumors. Excellent sensitivity (91.5%) and specificity (93.1%) were observed for immunohistochemical analyses as compared with the biochemical analysis of estrogen receptor for these tissues. The cancer component HSCORE correlated better with grade than did the biochemical estrogen receptor determination. Correlation was also observed between surgical stage and estrogen receptor content. Decreasing biochemical estrogen receptor content predicted advanced surgical stage (p = 0.0003), as did the total HSCORE (p = 0.003); however, the HSCORE of the cancer component only did not correlate with advanced surgical stage (p = 0.11). Although immunohistochemical analyses predicted biologic differentiation better than did the biochemical technique, stage correlated better with biochemical estrogen receptor analysis and total HSCORE than did the cancer component HSCORE. The HSCORE of the cancer component may better predict biologic behavior and therefore identify cancers more likely to respond to hormonal therapy.