CA125 is used to monitor which cancer?

• A. Ovarian adenocarcinoma
• B. Breast adenocarcinoma
• C. Pancreatic adenocarcinoma
• D. Choriocarcinoma

Answer: (A)

CA125 is a tumor marker most commonly used to monitor ovarian cancer, especially epithelial ovarian carcinomas such as ovarian adenocarcinoma. In patients with known disease, serial CA125 levels track how the tumor burden changes with treatment: decreasing levels suggest response, while rising levels can indicate progression or recurrence. It’s not routinely used to monitor breast, pancreatic, or choriocarcinoma, which rely on different markers or imaging. CA125 can also be elevated in benign gynecologic conditions, so it’s not used as a screening tool. Therefore, its role in monitoring aligns best with ovarian adenocarcinoma.