Back to home June 2012
Regional Cancer Center
Tumor Markers Help Physicians Detect Cancer
Medical tests give physicians answers to questions they have about a patient's condition. One type of test is tumor markers. Tumor markers are blood proteins that are often, but not always, correlated with cancer.
Examples are Prostate Specific Antigen (PSA) for prostate cancer and CA125 for ovarian cancer. Oncologist, Lowell Hart, M.D., says that people always have a small amount of these proteins in their blood but cancer patients, especially those with advanced cancers, often have higher levels.
"Other markers are CEA for colon cancer—this sometimes shows up in breast or lung cancer, also—and CA27-29 for breast cancer and CA19-9 for esophageal, stomach or pancreatic cancer," Dr. Hart says. "Generally, except for PSA, these are not good enough to be used for screening of patients without symptoms. Even in prostate cancer, PSA screening is controversial, especially in very old men who may have slow moving cancers. I generally recommend that men older than 50—older than 40 in African-American men—get a yearly PSA and prostate exam if possible."
If a patient has a high level of a tumor marker, the results can help physicians follow them to be sure their treatments are working, and to diagnose a recurrence early. "Sometimes they can lessen the need for expensive scans and are, therefore, cost efficient," Dr. Hart says.
A new type of marker is circulating tumor cells (CTC), which is done by a machine counting cancer cells in the blood for patients with known metastatic prostate, breast or colon cancer.
"If the number is declining, the treatments are working; if increasing, it is time to switch to another therapy," Dr. Hart says. "However, sometimes patients with advanced cancers do not have detectable numbers of cancer cells in their blood."
New research will soon improve these tests so even smaller numbers of cells or even DNA from tumors can be measured in the blood. "I predict that fairly soon we will be following our patients almost exclusively with blood testing rather than scans," Dr. Hart says.
""...Sometimes patients with advanced cancers do not have detectable numbers of cancer cells in their blood."
Advancements in Detecting & Treating Breast Cancer
Lowell Hart, M.D.
Florida Cancer Specialists
8931 Colonial Center Drive
Fort Myers, FL 33905