Background and aim: Endometrial carcinoma is the most common female pelvic genital malignancy. The strong association between the development of endometrial cancer and influence of steroid hormones (especially estrogen) was demonstrated in many studies. Mucinous carcinoma is an uncommon type of endometrial carcinoma. Most cancers are low grade and have a relatively good prognosis. The expression of one type of estrogen (ER) and progesterone receptor (PR) has been well documented. Recently, two new types of receptors (ER-beta and PR-B) were demonstrated. The aim of this study was to determine the expression of all four steroid receptors (ER-alpha, ER-beta, PR-A and PR-B) in human mucinous carcinoma of the endometrium.
Patients and methods: An immunohistochemical hormone receptor assay using specific monoclonal antibodies against estrogen receptors (ER-alpha, ER-beta) and progesterone receptors (PR-A and PR-B ) was used to study formalin-fixed and paraffin-embedded slides of 12 patients, diagnosed with primary endometrial mucinous carcinoma of different histological grades (G1 n = 9; G2 n = 3; G3 = 0).
Results: Three types of steroid receptors (ER-alpha, PR-A and PR-B) were frequently expressed in mucinous adenocarcinoma. ER-beta was weakly expressed in only one analyzed case. The immunohistochemical expression of PR-B demonstrated a statistically significant decrease in G1 neoplasms in comparison to G2 (p < or = 0.001).
Conclusion: We demonstrated the expression of four different steroid receptors in mucinous endometrial carcinoma. No significant differences between different histological grades of tumor with respect to ER-alpha and ER-beta expression were observed. Interestingly, a statistically significant increase in expression of PR-B in G2 neoplasms compared to G1 was demonstrated. The higher expression of PR-B in G2 tumors suggests a substantial function of progesterone, and thus progesterone receptor, in the malignant transformation of mucinous endometrial cancer. Therefore, PR-B expression might be utilized as a tumor marker to distinguish between G1 and G2 mucinous tumors. However, additional studies are necessary to evaluate whether these parameters could be used as tumor markers for endometrial cancer.