Introduction/Background The transcription factor Sox2 is highly expressed in embryonic stem cells and is considered to act as a key driver of stem-like properties of cancer cells.

Methodology This study aimed to investigate the immunohistochemical expression profile of Sox2 in ovarian serous epithelial cancer, to determine its potential significance in disease prognosis, association with clinical and pathological parameters, as well as with patient survival.

Results A total of 270 patients were enrolled in the study. In FIGO stage I tumors Sox2 expression was absent in 28.9% of the tumors, while high Sox2 expression was significantly less frequent (7.0%, p <0.01). Significantly higher Sox2 expression compared with low expression was found in the third FIGO stage (65% vs.43.2%; p <0.01). Disease progression was recorded in 23.1% of patients with high Sox2 expression, which is significantly higher in comparison to patients without Sox2 expression (11.4%; p <0.05). Partial remission was observed in 14.1% with high Sox2 expression and this was significantly lower than in subjects with low Sox2 expression (28.8%; p <0.05) or without Sox2 expression (34.3%; p <0.01). Overall survival was the longest in the group without Sox2 expression, while the mortality was more prevalent in the group with high expression, but without statistical significance.

Conclusion The study showed that Sox2 overexpression in ovarian serous epithelial cancer was associated with the unfavorable clinical course of the disease.

Disclosures No