CA 27.29 (Breast Cancer Marker) is also known as the Cancer Antigen 27-29 breast cancer marker. This test makes it possible to detect the amount of cancer antigen present in the blood. A blood test can be ordered to find out if the cancer is metastatic and if it has spread even before you start with the treatment. It can also determine how well the treatment is working and if the cancer has come back or spread after the treatment. The CA 27.29 (Breast Cancer Marker) test is used for following the treatment course in someone suffering from advanced breast cancer.

Cancers of the colon, stomach, kidney, lung, ovary, pancreas, uterus, and liver may also raise CA 27-29 levels. Noncancerous conditions associated with this substance are first trimester pregnancy, endometriosis, ovarian cysts, benign breast disease, kidney disease, and liver disease.