MUC16 and ovarian cancer: Cancer antigen 125 (CA-125) is produced by endometrial, peritoneal, and ovarian cells, which is normally used as a tumor marker of ovarian cancer.1 Besides the role in monitoring ovarian cancer therapy, high CA-125 levels is reported in both ovarian and non-ovarian diseases, malignant and nonmalignant conditions.2,3 The exact biological role of CA-125 in unknown, but it seems to act through several pathways due to its complex structure.4