Carcinoembryonic antigen (CEA) is a glycoprotein produced by the fetal digestive tract and certain types of cancer cells.While elevated CEA levels can indicate various cancers, including colorectal, lung, breast, and pancreatic, Its not a definitive diagnostic tool. CEA testing is primarily used to monitor treatment response, detect cancer recurrence, and assess prognosis in individuals with known cancer.

CA 15 - 3 is a blood test used to monitor breast cancer treatment and detect disease recurrence.It measures a protein called cancer antigen 15 - 3, which is produced by some breast cancer cells.Elevated CA 15 - 3 levels may indicate cancer progression or recurrence.However, Its not a diagnostic test for breast cancer, as other conditions can also cause elevated levels. CA 15-3 is most useful when combined with clinical assessment and other imaging tests.