CA-125 is elevated in most cases of epithelial OC (~80%) [9–11]; however, CA-125 is also known to be elevated in patients with benign tumors [3] and a variety of other health conditions such as endometriosis, uterine fibroids, diverticulitis and cirrhosis of the liver [10, 12–14]. Here, MUC16 is linked to endometriosis.