Introduction/Background This study aimed to determine the expression of HER2neu, MUC1, estrogen and progesterone receptors immunohistochemically and investigate its effects of the expressions of these markers on clinical-pathological features and prognosis in ovarian cancer.

Methodology The study group consisted of 86 patients diagnosed for epithelial ovarian cancer at Çukurova University Faculty of Medicine which were operated between June 2009 and November 14, 2018. Of these 86 patients; 46 of them are high grade serous ovarian cancer, 7 of them are low grade serous ovarian cancer, 14 of them are mucinous carcinoma,19 of them were in the histopathological type of clear cell carcinoma. MUC1, HER2neu,Estrogen, Progesterone antibodies were applied immunohistochemically to pathological samples of the patients and the expression status of these markers, relationship between clinical-pathological features and prognosis were analyzed by statistical methods.

Results In all patients in the low grade serous ovarian cancer and clear cell carcinoma groups MUC1 stained strongly positive.The frequency of MUC1 positive staining was lower in mucinous carcinoma; but it was observed that in high grade serous ovarian cancer it was higher (p<0.01). Half of the mucinous carcinoma group HER2neu stained strongly positive. In the high grade serous ovarian cancer pathology group who were resistant to platinum therapy estrogen receptor was found to be positive in all 16 patients.

Conclusion High positive staining of MUC1 was determined in low grade serous ovarian cancer and clear cell carcinoma group patients. The higher estrogen-progesterone receptor expressions in platinum resistant patients in high grade serous ovarian cancer group, the detection of HER2neu positivity in half of the population in the mucinous carcinoma group is an important result of this study. For targeted therapy results should be taken into account in these epithelial ovarian cancers which are difficult to manage.