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Screening Test for Ovarian CancerA breakthrough blood test is in the works. Meanwhile, be vigilant—learn the early warning signs
A potential screening test for ovarian cancer is in development that could identify women with early stage disease in as little as 30 minutes, using blood from a simple finger stick. Such a test could save thousands of lives. Right now, only 25 percent of ovarian cancers are detected in the early, most curable stage because there’s no reliable test. And most women aren’t aware that ovarian cancer can have early symptoms.
A new science leads to new test
The test, developed by a team of scientists from the National Cancer Institute (NCI) and the Food and Drug Administration (FDA), uses an artificial intelligence program that trains a computer to look for specific patterns of small proteins found in the blood of cancer patients. The isolation of such proteins is the result of a relatively new science called proteomics, the study of proteins inside cells and what they do.
The test was used on blood samples taken from women at a high-risk cancer clinic at Northwestern University in Chicago and from women in the general population explains Lance Liotta, MD, PhD, senior investigator in the study at the NCI’s Center for Cancer Research. “The test was able to correctly identify 50 out of 50 samples from women with ovarian cancer, and 63 of 66 samples from women with non-cancerous conditions. And it was able to classify all 18 samples from women with stage I cancers,” says Dr. Liotta. “That’s a positive predictive value of 94 percent.”
In contrast, the tests currently used to help diagnose ovarian cancer—transvaginal ultrasound and CA125 (a protein elevated in ovarian cancer and conditions like endometriosis)—were able to identify only 25 percent of the women with cancer. “These patterns of proteins can be much more accurate than a single marker,” adds co-researcher Emanuel Petricoin, PhD, of the FDA’s Center for Biologics Evaluation and Research.
Clinical trials are now underway at the NCI to confirm the accuracy and sensitivity of the proteomic test, using blood samples from cancer centers around the country. The proteomic test will be tested in combination with ultrasound and CA125 in future trials. If large-scale clinical trials confirm the early data, published February 7, 2002 in The Lancet, the test could become available in a few years.
Late diagnosis—lost lives
An accurate and early test for ovarian cancer could not come too soon. An estimated 23,300 women will be diagnosed with ovarian cancer this year; nearly 14,000 will die.
When ovarian cancer is diagnosed and treated early (in stage I), five-year survival is about 95 percent; the survival rate drops to 20 percent for later-stage cancers.
“Ovarian cancer is one of our most lethal cancers because it is almost always diagnosed late, when it has already spread beyond the ovary, and we lose almost half of women with ovarian cancer,” remarks Thomas A. Caputo, MD, director of Gynecologic Oncology at the New York Weill Cornell Medical Center. “If this test proves accurate, specific, and reproducible, with few false positives, it would be a true breakthough.” Telltale warnings
Ovarian cancer has always been regarded as a “silent killer,” because it was believed to have no early warning signs. But a series of recent studies shows that women do have early symptoms.
A study published in the August 2001 Obstetrics & Gynecology among 168 women with ovarian cancer found that 93 percent had at least one symptom—such as bloating, fullness, pressure on the abdomen, back pain, or fatigue—in the year before their diagnosis.
Another study of 52 patients at Evanston Northwestern Healthcare in Illinois, showed that urinary symptoms triggered surgery for early ovarian cancer in up to 11 percent of patients. The women had a persistent urge to urinate or leakage due to that urge, which often occurred with a change of position (also a symptom of urge incontinence).
A larger study, published in the November 15, 2000, issue of the journal Cancer, surveyed 1,725 women with ovarian cancer in 46 states and four Canadian provinces, and found 95 percent had symptoms before their diagnosis. Most importantly, women who ignored their symptoms were much more likely to be diagnosed with advanced ovarian cancer.
The Ovarian Cancer National Alliance (OCNA) advises seeing a doctor if such symptoms seem unusual to you or persist for several weeks. Because these symptoms may be non-specific, you may need to be assertive when alerting your doctor to their persistence, says Ann Kolker, the executive director of OCNA and an ovarian cancer survivor.
What the new test could do
If your doctor suspects ovarian cancer, you’ll likely have a pelvic exam, transvaginal ultrasound, and a CA125 test. The proteomic test could find its first use as an adjunct to those tests, since they’re not reliable. Pelvic exams can miss a third of tumors, and CA125 is elevated in only 50 to 60 percent of stage I cancers. Eventually, the test might be used to screen women in the general population. “What’s important is the blood samples tested with the proteomic test were taken from women before they were diagnosed with ovarian cancer, and from women with conditions that raise CA125, and the test accurately identfied women later found to have cancers,” says Dr. Petricoin.
For now, vigilance is your best defense. OCNA has begun a public education program to raise awareness of ovarian cancer and its early warning signs. Its prophetic theme: “Until there’s a test, awareness is best.” Additional reporting by Peggy Eastman
This article originally appeared in the March 2002 issue of Women's Health Advisor.
