A new screening strategy for ovarian cancer appears to be highly specific for detecting the disease before it becomes lethal. The strategy is described in a study published early online in Cancer, a peer-reviewed journal of the American Cancer Society. If verified in an ongoing clinical trial, it could potentially help save the lives of thousands of women each year.

There currently are no established screening strategies for ovarian cancer. The disease often causes no specific symptoms and is difficult to detect in the early stages when it is most responsive to treatment. Therefore, ovarian cancer is highly lethal because most women have advanced disease when they are diagnosed.
Karen Lu, M.D., of The University of Texas M.D. Anderson Cancer Center in Houston, led a team that tested the potential of a two-stage ovarian cancer screening strategy that incorporates changes in a blood protein called CA125, which is a known tumor marker.

For the prospective, single-arm, 11-year study, 4,051 women were enrolled from seven sites across the country, with MD Anderson serving as the lead site. All were healthy, post-menopausal women, ages 50-74, with no strong family history of breast or ovarian cancer. The study's primary endpoint was specificity, or few false positives. In addition, the study looked at the positive predictive value, or the number of operations required to detect a case of ovarian cancer.

Each woman received a baseline CA-125 blood test. Using the Risk of Ovarian Cancer Algorithm (ROCA), a mathematical model based on the patient's age and CA-125 score, women were stratified to one of three risks groups, with the respective follow-up: "low," came back in a year for a follow-up blood test; "intermediate," further monitoring with repeat CA-125 blood test in three months; and "high," referred to receive transvaginal sonography (TVS) and to see a gynecologic oncologist.

Based on the women's CA-125 change over time, the average annual rate of referral to the intermediate and high groups were 5.8 percent and .9 percent, respectively. Cumulatively, 85 women (2.9 percent) were determined to be high risk, and thereby received the TVS and were referred to a gynecologic oncologist. Of those women, 10 underwent surgery: four had invasive ovarian cancer; two had borderline disease; one had endometrial cancer and three had benign ovarian tumors – a positive predictive value of 40 percent, which greatly surpasses the clinical benchmark of 10 percent, say the researchers. The specificity of the test was 99.9 percent, explained Lu. The screening failed to detect two borderline ovarian cancers.

Of great importance, said Lu, is that the four invasive ovarian cancers detected were high-grade epithelial tumors, the most aggressive form of the disease, and were caught early (stage IC or IIB), when the disease is not only treatable, but most often curable. Lu also noted that all four women found to have invasive disease were monitored at low risk for three years or more prior to a rising CA-125.

The findings indicate that this screening strategy achieves high specificity with very few false positive results in post-menopausal women. "The results from our study are not practice-changing at this time; however, our findings suggest that using a longitudinal  screening strategy may be beneficial in post-menopausal women with an average risk of developing ovarian cancer," said Dr. Lu. "We are currently waiting for the results of a larger, randomized study currently being conducted in the United Kingdom that uses the same Risk of Ovarian Cancer Algorithm in a similar population of women. If the results of this study are also positive, then this will result in a change in practice."

The study is continuing; and, as follow-up, Lu and her team plan to look at combining other markers with CA-125 to determine the screening impact of their combined change over time.

The study was supported by the National Cancer Institute, and was a research project of MD Anderson's ovarian cancer Specialized Program of Research Excellence (SPORE), NCI P50 CA83639, the Bioinformatics Shared Resources of MD Anderson CCSG NCI P30 CA16672, the National Foundation for Cancer Research. It has also received philanthropic funds from Golfers Against Cancer, the Tracy Jo Wilson Ovarian Cancer Foundation, the Mossy Foundation, the Norton family and Stuart and Gaye Lynn Zarrow.

In addition to Lu, and Bast, other authors on the study include: Theresa Bevers, M.D. Department of Clinical Cancer Prevention, Herbert Fritsche, Ph.D., Department of Laboratory Medicine, Deepak Bedi, M.D., Department of Diagnostic Radiology, Michael T. Deavers, M.D., Department of Pathology and Clinical Pathology; Charlotte Sun, Dr.PH, Department of Gynecologic Oncology, Mary A. Hernandez, Office of Translational Research, all with M.D. Anderson; Steven Skates, Ph.D., Massachusetts General Hospital and Harvard Medical School; Olasunkanmi Adeyinka, M.D., UT Physicians Family Physicians; William Newland, M.D., The Iowa Clinic; Richard Moore, M.D. and Cornelius Granai, M.D., both with Women & Infants Hospital, Brown University; Leroy Leeds, M.D., OGA Medical Center; Steven Harris, M.D., OB/GYN Associates of Dallas; Jeremy Geffen, M.D., Geffen Cancer Research Institute; and Nora Horick, Harvard Medical School and Massachusetts General Hospital.

As a co-inventor of the CA-125, Bast receives royalties from, and has served as an advisor to, Fujirebio Diagnostics, Inc.