Book Excerpt: Medical Tests That Can Save Your Life

CA-125 and TVU Tests For Ovarian Cancer

The carcinogenic antigen (CA) 125 blood test measures levels of a protein that is normally confined within a cell. If, however, cell walls are inflamed or damaged, the protein may be released into the bloodstream. Ovarian cancer cells may produce an excess of these protein molecules, and therefore the CA-125 test can help in diagnosing and monitoring this disease.

It's important to remember that simply measuring blood levels of CA-125 alone cannot effectively find early ovarian cancer. In many early-stage ovarian cancers, this molecule is not necessarily released in large amounts. False positives can also occur, as other conditions (endometriosis, the first trimester of pregnancy, or non-gynecological cancers) will elevate CA-125. In conjunction with a transvaginal ultrasound (TVU) screening, however, the CA-125 test can be very effective.

A transvaginal ultrasound, also known as an endovaginal ultrasound, involves the use of sound waves to delineate internal structures with a transducer placed in the vagina.

For this test, you lie on an examining table, on your back. A light sheet is provided to cover you during the procedure. A small handheld transducer that is covered with a latex condom is inserted into your vagina. The transducer produces images that can be seen on a video monitor, and a hard copy can be made on film. The test is completely painless and does not take much time.

Transvaginal ultrasound imaging is recommended for ovarian cancer screening in asymptomatic women at high risk for developing ovarian cancer. In a 1997 study of 14,469 women with no symptoms of ovarian cancer, researchers detected 17 ovarian cancers with TVU. Women who had abnormal findings on the first screening underwent additional tests to make sure the abnormality was not an ovarian cyst. Those who found that they did not have cysts then underwent a series of blood and ultrasound tests to determine whether there was a need for surgery. After surgery, researchers determined that 11 of the 17 cancers were Stage I (early stage). Although the total number of ovarian cancers detected was small, 65 percent of these tumors were detected at a stage when they are most likely to be curable.

Our Recommendations

Women at High Risk for Ovarian Cancer

Women at high risk for ovarian cancer should have a baseline TVU combined with a blood CA-125 measurement, followed by an annual CA-125 measurement and a TVU every 2 years. The TVU should be followed up more frequently if CA-125 is found to rise significantly from one year to the next and there are no other problems that can explain the rise.

Of these women, those with a strong family history of either ovarian or breast cancer (two or more first-degree relatives have or had the disease) should begi
TVU and CA-125 screening 5 years prior to the earliest age of onset in their family.

Women at Moderate Risk

Women in the moderate-risk category should discuss their individual circumstances with their doctor to determine the best course of action. Monitoring blood levels of CA-125 annually for significant elevations from one year to the next, beginning at age 40, is one logical option for these women.

Women at Low Risk

Women who are at low risk for ovarian cancer should probably not be screened with TVU, as the percentage of women screened who are likely to benefit will be very small. As with moderate-risk women, an annual CA 125 test, beginning at age 40, is a good idea.

We cannot stress enough that early screening for ovarian cancer is underutilized by women who are at elevated risk for the disease in this country. A report in Gynecologic Oncology from researchers at the Fred Hutchinson Cancer Research Center in Seattle stated that "women at highest risk for ovarian cancer receive less screening and report less worry about getting the disease than women with a lower risk."

Their report revealed that while more than 60 percent of those women at elevated risk for ovarian cancer reported having undergone screening for breast cancer, less than half (47 percent) of the high-risk women said they had been screened for ovarian cancer.

"Most of the highest-risk women for ovarian cancer are at high risk because their relatives have had breast cancer, not ovarian cancer," the report states. "However, it appears that many of these women don't make the association between a family history of breast cancer and increased ovarian cancer risk. The connection isn't as obvious as it would be if their mother or sister, for example, had ovarian cancer."

Health Risks of the Screening Tests

There are essentially no health risks associated with either the TVU or the CA-125 blood tests.

Cost of the Tests

A TVU currently runs about $200 to $250, a CA-125 blood test about $60. Women who carry BRCA1 or -2 gene mutations may be able to get their health insurance companies to pay for these screening exams, due to their greatly increased risk. However, if you have these mutations but have not informed your insurance company, you may not want to ask for reimbursement for these tests based on your higher risk.

Another possible option for women concerned about ovarian cancer is to inquire about enrolling in the Risk of Ovarian Cancer Algorithm Study (ROCA). Women who participate in the ROCA study will have their CA-125 serum levels checked every 3 months for 1 or 2 years, and a TVU of the ovaries also may be recommended. For more information, go to the Cancer Genetics Network (CGN) Web site (http://epi.grants.cancer.gov/ovarian/). Several different medical centers across the United States are participating in this study.

Reprinted from: Medical Tests That Can Save Your Life: 21 Tests Your Doctor Won't Order ...Unless You Know to Ask by David Johnson, Ph.D., and David Sandmire, M.D. with Daniel Klein © 2004 by David Johnson, Ph.D. and David Sandmire, M.D. (August 2004; $14.95US/$21.95CAN; 1-57954-732-X) Permission granted by Rodale, Inc., Emmaus, PA 18098. Available wherever books are sold or directly from the publisher by calling (800) 848-4735 or visit their website at www.rodalestore.com.