Estrogen and progesterone are important hormones secreted by the ovary acting through specific receptors. Tumor tissue expression profiles of these have demonstrated prognostic value in malignancies such as breast, uterine and prostate cancer. In this study, including tissue samples from 773 Danish patients with an ovarian tumor, we evaluated whether estrogen receptor (ER) and progesterone receptor (PR) expression correlated with clinico-pathological parameters, and a possible prognostic impact on ovarian cancer (OC) patients was investigated. Using tissue array and immunohistochemistry, we analyzed the ER and PR expression levels in tissues from 582 women with OC and 191 women with low malignancy potential (LMP) ovarian tumors. Our results demonstrated that ER was expressed in 30 of the 191 LMP tumors (16%) and in 207 of the 582 OC (36%). PR was expressed in 38 LMP tumors (20%) and in 115 OC (20%). For both tumor types an excess of positive tumors was found in the serous compared to the mucinous subtype (p≤0.00001). The frequency of ER expression-positive OC increased with increasing FIGO stage (p=0.0003), and the frequency of PR-positive tumors increased with increasing histological grade (p=0.0006). In a Cox survival analysis, a tissue ER and PR expression 10% or higher was found to imply an independent significant advantageous course of patient disease-specific survival (ER: hazard ratio (HR), 0.80; 95% confidence interval (CI), 0.63-0.99; PR: HR, 0.69; 95% CI, 0.51-0.94) together with FIGO stage, residual tumor after primary surgery, age at diagnosis and other histological types vs. serous adenocarcinoma. The histological grade of tumor was found to have no independent prognostic value. The prognostic value of ER and PR was found additive with a HR for patients with high ER and PR expression of 0.48 (95% CI, 0.31-0.74) compared to patients with <10% expression for both receptors. In conclusion, our results predict that an elevated expression of ER and PR, alone and in combination, point to a favorable outcome for patients with OC.

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