PROM1 and benign neoplasm: Additionally, the CD133 expression was shown to correlate with ovarian tumor aggressiveness–the highest expression of CD133 was observed in malignant epithelial ovarian tumors when compared to borderline (with moderate expression) and benign tumors (low expression), as well as with a histological type–serous ovarian carcinomas showed the highest immunohistochemical expression score of CD133 [73].