Misconceptions About the CA125 Blood Test

"THIS IS VERY IMPORTANT! PASS THIS ALONG TO EVERY WOMAN YOU KNOW! " the e-mail begins, followed by a touching story about a woman with ovarian cancer.

The writer explains that she is trying to save other women from her same fate - if only she had known earlier about the CA125 blood test to detect ovarian cancer. She tells readers to demand that their gynecologist give them a CA125 blood test as part of their yearly exams and "Don't take 'No' for an answer!"

This and many similar stories are circulating among e-mail users and stirring up misconceptions about the CA125 blood test. While this woman's story, if true, is touching, her information regarding CA125 is incorrect.

"Unfortunately, the CA125 blood test is not the ultimate way to detect ovarian cancer," said Dr. Diane Bodurka, assistant professor in M. D. Anderson's Department of Gynecologic Oncology. "We do not have a fool-proof way to detect ovarian cancer in its early stages. That is something we are working towards."

CA125 is a substance sometimes found in an increased amount in the blood, other body fluids or tissues that may suggest the presence of some types of cancer. The blood test is used to measure the level of CA125, the most common tumor marker in ovarian cancer.

"The problem with CA125 is two-fold," Dr. Bodurka said. "In half of the ovarian cancer cases that are diagnosed early - that is, when the cancer is limited to the ovary - the CA125 is normal. Additionally, there are many false positives such as endometriosis, menstruation, pregnancy, liver disease, or other pelvic infections, which result in a higher CA125 level."

Because of the many reasons this level can be higher, gynecologic oncologists suggest the CA125 test in combination with a pelvic/rectal exam and a transvaginal sonogram as part of a diagnostic exam for ovarian cancer screening, Dr. Bodurka said.

However, there are benefits to the blood test. "Eighty percent of the women with advanced disease have an elevated CA125 level," Dr. Bodurka said. "The test is also helpful when administered to ovarian cancer patients during chemotherapy because it adds another piece of useful data for oncologists - to ensure the treatment is working."

What is correct in the e-mail is that it is important to be proactive in one's health care by scheduling regular exams and screenings. One in 58 women, at any age, will get ovarian cancer. Symptoms for ovarian cancer are subtle, persistent and usually increase over time. Early detection is key.

Visit the M. D. Anderson Blanton-Davis Ovarian Cancer Research Program website to make an appointment for a screening or to learn more about ovarian cancer, or visit the National Cancer Institute's CancerNet website.