CA 27.29 is a cancer marker that was approved by the Food and Drug Administration in 1996 as a tumor marker for breast cancer. This test measures the levels of CA 27.29 antigen found in the blood of patients with breast cancer. If the cancer spreads, the levels of CA 27.29 should also rise. Monitoring this tumor marker helps physicians evaluate the progression of the disease. This tumor marker can be used along with two other tests, CA 15-3 and CEA. These markers can rise not only in cases of breast cancer, but also in other cases. CA 27.29 can also rise in cases of liver, pancreatic and ovarian cancers and also in non-cancerous conditions.
It should be noted that these blood tests are not highly sensitive or specific, so it may yield both false positive and false negative results such as indicating that a tumor is progressing when it isn’t or vice versa. It is most helpful to know the CA 27.29 blood level when monitoring the progression or spread (metastasis) of breast cancer to other organs in patients who have already received the diagnosis of metastatic breast cancer. This way, oncologists can make changes to the treatment plan accordingly.
Based on a retrospective study conducted at Penn State Hershey Cancer Institute, published in the 2011 issue of “The Open Breast Cancer Journal”, which involved the chart reviews of almost 400 breast cancer patients, there is uncertainty about the role of CA 27.29 in the early stages of breast cancer. However, the authors indicate that CA 27.29 correlates with the progression of the disease in cases of metastasis (while being aware of possible false positive results). More studies are needed to further evaluate the role of this tumor marker in cases where the cancer progresses locally and in cases where it spreads to distant organs.
Considering its limitations and the fact that it is not highly accurate, the American Society of Clinical Oncology (ASCO), does not recommend this test to be done routinely in all cases of breast cancer. In addition, research studies suggest that using this test before a patient experiences symptoms (i.e. bone pain, difficulty breathing, weight loss) does not improve her survival or help her have a better quality of life. Currently, ASCO recommends monitoring this tumor marker in conjunction with imaging, patient history and clinical examination.
However, the patient can discuss the possibility of getting this test done with her cancer specialist, regardless of the stage of the disease. In this case, the test can be done every 3 to 6 months. Rather than using CA 27.29, specialists recommend other tests that can monitor breast cancer cases such as chest X-rays, CT scans, bone scans or liver tests.
The normal values of CA 27.29 are less than 38-40 U/ml. It should be noted that this tumor marker may yield false positive results in some non-cancerous conditions such as benign ovarian cysts, endometriosis, benign breast disease, kidney and liver diseases or during pregnancy.