MUC16 and leiomyoma: Even though serum Cancer Antigen 125 (CA125) is considered the “gold standard” biomarker for OC, it has low sensitivity in the early stages (I–II), as it is only elevated in 26–50% of stage I diseases and has low specificity (sometimes leading to false positives) during menstruation and conditions such as fibroids and endometriosis.