Evaluating its change over time, CA-125, the protein long recognized for predicting ovarian cancer recurrence, now shows promise as a screening tool for early-stage disease, according to recent study results presented by Karen Lu, M.D., professor in MD Anderson's Department of Gynecologic Oncology.
During this study 3,252 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 risk groups, with the respective follow-up: "low," came back in a year for a follow-up blood test; "intermediate," further monitoring with repeat CA125 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 6.8% and .9%, respectively. Cumulatively, 85 women (2.6%) were determined to be high risk and thereby received the TVS and were referred to a gynecologic oncologist. Of those women, eight underwent surgery: five were found to have ovarian cancer, three with invasive and two with borderline disease; and three had benign tumors - a positive predictive value of 37.5%. Consequently, no more than three operations would be required to detect each case of ovarian cancer, Lu expalins. The screening failed to detect two borderline ovarian cancers.
Each year, about 22,000 women in the United States are diagnosed with ovarian cancer.
The symptoms of ovarian cancer are often common and vague, which makes it difficult to diagnose. Currently, there is no effective early detection method for ovarian cancer. It is usually diagnosed in advanced stages, and only about half of women survive longer than five years after diagnosis. For the 25% of ovarian cancers that are found early, the five-year survival rate is greater than 90%.