IntroductionPredictive markers of platinum-based chemotherapy efficacy in patients with ovarian cancer have been widely discussed in recent years. Oestrogen receptors (ER) are involved in regulation of proliferative factors responsible for tumour growth, so they could predict the effectiveness of anticancer chemotherapy. The aim of the study was to determine the predictive value of ER-beta expression in a cohort of ovarian cancer patients treated with platinum and taxanes. The level of ER-beta expression was correlated with progression-free survival and also with a number of disease relapses during 40 months of monitoring.Material and methodsThe quantitative immunofluorescence flow cytometry analysis was performed to detect ER-beta in 34 serous ovarian cancer surgical specimens. All the patients were treated with the first line platinum and taxane-based regimen. The primary anti-ER-beta (ab14C8) and the secondary antibodies (DyLight650, ab98729) were used for the analysis. The level of ER-beta expression was calculated by Kolmogorov-Smirnov statistical test as the ratio (%) of specifically fluorescent cells to the number of cells incubated only with secondary antibodies. Association of ER-beta expression levels with progression-free survival was analysed using the Kaplan-Meier method and log-rank tests.Results and discussionsER-beta were revealed in all tumour specimens tested and the median value of the expression level was 41,5%. Patients were dichotomized in groups with low and high level of ER-beta expression, below- and above-median value respectively. Significant differences were shown between these groups. First, median of progression-free survival was larger in the high-level expression group as compared to the low-level expression group – 25,5 vs 8 months. Second, the disease rate during 40 months of monitoring was lover in the high-level expression group as compared the low-level expression group – 6 vs 15 respectively.ConclusionA quantitative index of the ER-beta level expression in tumour tissue predicts the efficacy of the first line platinum and taxane-based chemotherapy in ovarian cancer patients. Progression-free survival was about 3.0 times longer and the number of the disease relapses during 40 months of monitoring was 1.5 times less in patients with high level of ER-beta expression. The study was supported in part by RSF 17-75-10212.