Your CA-125

It is important to understand what your CA-125 is and how it is used. The CA-125 is a sugar associated protein called a glycoprotein found in the blood. It is commonly referred to as a tumor marker because it provides information about a disease’s biological state and its level can be measured when obtained from the blood. However, to be more accurate from a scientific standpoint, it is considered a tumor associated protein. Why? Because an elevated CA-125 level does not always mean a woman has ovarian cancer. CA-125 levels can sometimes be misleading.

The CA-125 is used several ways once a woman has been diagnosed with ovarian cancer, and during the course of her treatment and follow up care. According to Drs. Herzog and Coleman, there are four primary roles for CA-125 assessment that have been established with varying degrees of clinical use and reliability.

The first role is to inform outcome. There are studies that have shown the CA-125 level can be linked to both short-term and long-term outcomes when evaluating population trends. From a trending perspective, it can indicate if surgery will be “optimal”, the likelihood all disease will be gone at the first evaluation, time until the tumor could recur as well as the tumor’s response to various modes of therapy.

The second role is to detect recurrent disease. This is when Drs. Herzog and Coleman felt the CA-125 is most reliable and useful; when it is used to detect the recurrence of ovarian cancer in a woman previously diagnosed and treated for the disease. While there are exceptions to everything, in most cases when the CA-125 value rises over a series of tests there is a very strong possibility that a patient is experiencing a recurrence of the disease.

However; it is possible to have a recurrence without a rise in the CA-125 value and it is possible to have a rise in the CA-125 value and not experience a recurrence.

The third role is to monitor treatment. In this instance the CA-125 can be a reliable tool when used in conjunction with a thorough history and physical exam to monitor a patient’s treatment. This is true when a woman has an elevated initial CA-125 value. It is also important to keep in mind that the CA-125 is just one piece of this overall evaluation when determining if treatment is effective or not.

The fourth role is to screen for ovarian cancer. As we all know early detection leads to a higher cure rate. Since there is not an effective screening test for ovarian cancer, the CA-125 level can play a role in this process. If the level is used on its own, this is not true. But when used as an ingredient with other markers in a recipe for early screening, it can be used more successfully.

Drs. Herzog and Coleman want women with ovarian cancer to keep in mind that their CA-125 test is only one indication of how well they are responding to treatment. There are many other variables that should be considered and individualized for each patient. The best course is to sit down with your doctor and the rest of your medical care team and ask questions about the CA-125 test and your individual results. Asking questions provides you with the ability to stay informed and, in some cases, resist the urge to make assumptions about how your numbers are being interpreted and utilized.

This article was originally published in Coping® with Cancer magazine, September/October 2009: CA-125, What Does This Test Mean to You by Dr. Thomas J. Herzog and Dr. Robert L. Coleman. Dr. Herzog is a professor of Clinical Obstetrics and Gynecology at Columbus University and the Director of Gynecologic Oncology at the Herbert Irving Comprehensive Cancer Center in New York, NY. Dr. Robert L. Coleman is the director of clinical research in the Gynecologic Oncology Dept. at the University of Texas, M.D. Anderson Cancer Center in Houston Texas.