Background: Ovarian neoplasms are most often found in women with an incidence of 80% of benign tumors and the rest are malignant tumors of the ovary. Ovarian cancer in Indonesia ranks third most cases that occur in women after breast cancer and liver cancer. Serous epithelial ovarian tumors are the most common subtype of ovarian cancer. SOX2 (SRY/sex determining region Y-box2) is a transcription factor that plays a role in cell proliferation and is also a marker of cancer stem cells. The presence of these cancer stem cells will affect the success of therapy because they are resistant to chemotherapy and radiotherapy. Aim: Knowing how to assess the expression and how the immunohistochemical expression of SOX2 in benign and malignant ovarian serous tumors. Method: This study is a descriptive analytic study using surgical tissue paraffin block preparations from patients with a diagnosis of benign and malignant ovarian serous tumors in the Anatomical Pathology Unit of HAM Hospital Medan with 39 cases. This research has been approved by the Health Research Ethics Commission, Faculty of Medicine, University of North Sumatra. Results: Based on the immunohistochemical staining of SOX2, the benign subtype was found to be low in expression (71.4%), the low-grade subtype to have high expression (18.2%) and the high-grade subtype to have more high expression (81.8%). Conclusion: In this research it was found that the highest expression of SOX2 was found in the benign subtype with low expression, but in the high-grade serous subtype high expression was found.

immunohistochemical staining

ovarian serous tumors

benign and malignant

SOX2