Loss of oestrogen receptor (ER) and progesterone receptor (PR) expression in endometrial cancer cells indicates poor prognosis. The aim of this study was to determine the correlation of ER and PR expression in cancer cells and the surrounding myometrium with the disease progression. Immunohistochemical expression of ER and PR was detected in cancer and myometrial cells of patients with EC. ER was detected in 65.2% of cancer cells and in 88.4% of myometrial cells. PR was detected in 59.4% of cancer cells and in 84.1% of myometrial cells. The 5-year overall survival (OS) was 76.8%. Patients with ER and PR negative EC had a shorter period until recurrence (p = .013 and .043) and shorter OS (p = .011 and .066) than those with ER and PR positive cancer. Negative ER and PR status in EC has an impact on recurrence and poor OS. The status of hormone receptors in myometrium may be useful in disease prognosis. Impact Statement The status of hormone receptors in endometrial cancer has been the subject of numerous studies and loss of hormone receptors indicates higher tumor grade and higher clinical stage, lympho-vascular space invasion and deeper myometrial invasion. Although, the communication between the endometrium and myometrium is crucial under physiological conditions, the status of hormone receptors in the myometrium and its significance in cancer progression is poorly studied. Our results showed that loss of ER in the myometrium indicate poor prognosis. The assessment of hormone receptor status in myometrium might be useful in predicting the course of the disease. Results of our research support the theory that stromal and myometrial cells may contribute to tumorigenesis in endometrial cancer. Better understanding of ER/PR expression in myometrial cells is needed, and our research opens new possibilities for identification of key pathways and new potential target molecules in EC prognosis and treatment. It is probable that future classification of endometrial cancer will rely on molecular sub-typing, where the status of hormone receptors in the myometrium might play an important role.
Keywords: Endometrial carcinoma; hormone receptors; myometrium; prognosis; prognostic factors; survival.