What cancer is indicated by an elevated CA 125 level?

An elevated CA 125 level is most commonly associated with surface-derived ovarian cancer. CA 125 is a tumor marker that is often used in the monitoring of ovarian cancer due to its higher expression in malignant ovarian tumors, particularly those arising from the epithelial cells on the surface of the ovaries. While it can be elevated in other conditions, including benign diseases and other malignancies, it is especially noted for its role in ovarian cancers.

In the context of ovarian cancer, particularly serous papillary carcinoma, CA 125 levels are used to assess the disease's presence and progression, as well as to monitor response to treatment. Elevated levels can aid in diagnosis, particularly in women who present with symptoms suggestive of ovarian cancer.

In contrast, while CA 125 may have limited elevations in other cancers or conditions, such as endometriosis, pelvic inflammatory disease, or even breast cancer, it is not specific enough to be a definitive marker for those types of tumors. Hence, surface-derived ovarian cancer is the primary cancer associated with substantially elevated CA 125 levels.