Cancer cells sometimes secrete specialized proteins into the bloodstream that serve as indicators of tumor growth. These tumor markers are often distinctly associated with a particular type of cancer. Like prostate cancer.

The most well-known tumor marker today is the PSA -- the prostate-specific antigen. PSA is a highly specific protein that is secreted only by cells of the prostate gland. It is one of the most widely used -- and the only widely accepted -- screening test for cancer.

There's also the tumor marker CA-125, used in the diagnosis of ovarian cancer and in the monitoring of response to treatment for the same disease. There's CEA for colon cancer, CA-19-9 for pancreatic cancer, AFP for liver and testicular cancer, beta-HCG for testicular cancer, and CA 15-3 for breast cancer. And research is under way on newer, more useful tumor markers. This is a good thing -- because some tumor markers are not specific enough or sensitive enough to accurately predict tumor growth.

This is why my oncologist does not recommend I enter the world of tumor markers, despite my status as a breast cancer survivor. He suggests I rely simply on how I feel for monitoring my chances for cancer recurrence. If I experience any worrisome symptoms, he will be the first to wage an all-out assessment of my health. But without symptoms, tumor markers are not likely to help me at all.

A peek at my breast cancer tumor markers would likely be hazy, inconclusive, and not all that helpful. Examination of tumor markers can lead to false positives. It can lead to expensive and often unnecessary follow-up testing. It can lead to worry and panic and even alarm if the numbers are not in the hoped-for range.

Although an abnormal tumor marker level may suggest cancer, this alone is typically not enough to diagnose the disease. Measurements of tumor markers are usually combined with other tests, such as a biopsy, to confirm cancer. So what would I do with an abnormal number and nothing suspicious to biopsy? I would worry. I would panic. Perhaps unnecessarily.

My doctor suggests I refrain from a wild cancer chase. And I am happy with his suggestion. Between my own awareness, follow-up oncology appointments, mammograms, annual OB/GYN check-ups, and more, I am confident any health issues that come my way will be detected early -- and can be resolved in good time. I have no need for confusing tumor marker details. Unless they are conclusively recommended, I will survive without them. More important, I will survive without worry.