This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Ovarian Tumors, Subject name: Gynaecology & Obstetrics
CA-125 is a marker antigen for the diagnosis of: 
Select and explain. 
A. Colon cancer, B. Breast cancer, C. Brain cancer, D. Ovarian cancer
D: Ovarian cancer
Answer: D: Ovarian cancer 
Explanation: CA 125 is a tumor marker for ovarian epithelial cancers ( high molecular weight glycoprotein(220 to 1000kd) CA 125 can also be high in cancers of the endometrium, fallopian tubes, lungs, breast and gastrointestinal tract. endometriosis several diseases of the ovary pregnancy adenomyosis fibroids liver disease pancreatitis peritonitis luteal phase of the menstrual cycle.