In vitro and epidemiological studies indicate an essential role for progesterone in the aetiology and progression of ovarian carcinoma. The aim of this study was to examine the prognostic role of progesterone receptor (PR) protein and mRNA expression.
PR expression was examined by immunohistochemistry (n=143) and kinetic reverse transcription-polymerase chain reaction (RT-PCR) from formalin-fixed and paraffin-embedded tissue (n=55). PR mRNA and protein expression correlated (P<0.0001). PR mRNA was a positive predictor for overall and progression-free survival (P=0.0005 and P<0.0001, respectively). Protein expression was also prognostic (P=0.015 and P=0.0011, respectively), whereas only PR mRNA retained its prognostic value on multivariate analysis (P=0.04). PR mRNA was still a positive prognostic marker among oestrogen receptor 1 (ESR1) mRNA-positive tumours (P=0.0007) and survival was best in patients with PR- and ESR1-positive phenotypes (P=0.0155 and P=0.0016, respectively).
Expression of PR and ESR1 defines a subgroup of ovarian carcinomas with a favourable prognosis. PR and ESR1 mRNA expression analysis is a sensitive, quantitative and easy-to-perform high-throughput analytical tool for the identification of this subgroup and could be predictive in clinical trials focused on patients with potential benefit from hormonal treatment.