Blood Tests

A host of blood tests can assess the health of different organs and systems in your body. Some doctors order "cancer markers" or "tumor markers" to detect possible cancer activity in the body. If cancer is present, it will usually produce a specific protein in the blood, that can serve as a "marker" for the cancer. CA 15.3 is the name of a protein used to find breast and ovarian cancers. CA125 may signal ovarian and breast cancer recurrence. TRU-QUANT and CA 27.29 are other examples of proteins associated with breast cancer, which your doctor may test for. CEA (carcinoembryonic antigen) is a marker for the presence of colon, lung, and liver cancers. This marker may be used to determine if cancer has spread to other areas of the body.

Some doctors rely on markers as an early indicator of disease progression or recurrence, with the hope of finding a local, curable tumor. If you have an elevated marker, your doctor may check that marker periodically to assess response to chemotherapy.

But these cancer markers, unlike the more reliable "PSA" test for prostate cancer, have limitations. For example, a marker test that registers normal does not prove that you are cancer-free, nor does an elevated test prove that you have progression or recurrence of cancer. While they may help along the road to diagnosis, the use of cancer markers to find metastatic cancer has not yet translated into better survival for women with breast cancer. You also have to consider the anxiety caused not just by an elevated blood marker, but by all of the tests that may be needed to try to find out where the increased marker is coming from. These tests can also be quite costly.