abstract: A prospective U.S. ovarian cancer screening study using the risk of ovarian cancer algorithm (ROCA)

ASCO (Post-Meeting Edition)
Abstract
5003
Background: There are currently no effective screening tools for the early detection of ovarian cancer in women at average population risk. We evaluated a screening strategy that incorporates change of CA-125 over time and age of the participant to estimate risk of ovarian cancer, referring a small fraction (2%) of apparently healthy individuals annually to transvaginal sonography (TVS).
Methods: A single arm, prospective, multicenter screening study enrolled postmenopausal women age 50 to 74 with no significant family history of breast or ovarian cancer. Participants underwent a CA-125 blood test annually. Based on the Risk of Ovarian Cancer Algorithm (ROCA) result, women were triaged to the next annual CA-125 (low risk), repeat CA-125 in 3 months (intermediate risk), or TVS and referral to a gynecologic oncologist (high risk). Based on clinical findings and TVS, the gyn onc made the decision whether to proceed with surgery.
Results: 3238 women participated over an eight year period. The average annual rate of referral to 3 monthly CA125 was 6.8%, and the average annual rate of TVS and gyn onc referral was 0.9%. Cumulatively 85 women (2.6%) received TVS and referral to a gyn onc. Eight women subsequently underwent surgery based on the TVS and referral, with 3 invasive ovarian cancers, 2 borderline ovarian tumors and 3 benign ovarian tumors, providing a positive predictive value of 37.5% (95% CI 8.5%,75.5%).The combined specificity of ROCA followed by TVS for referral to surgery is 99.7% (95% CI 99.5%, 99.9%). The 3 invasive ovarian cancers were high-grade epithelial tumors that were all early stage (two stage 1C and stage IIB). All 3 women with invasive ovarian cancer had at least 3 years with low risk, annual CA-125 values prior to a rising CA-125.
Conclusions: In this prospective, single arm study, the ROCA followed by TVS demonstrated excellent specificity and PPV in a population of U.S. women at average risk for ovarian cancer. As expected, less than 1% of participants annually required a TVS. In addition, the invasive high-grade ovarian cancers that were detected were early stage. This study provides early evidence that ROCA followed by TVS is a feasible strategy for screening women over 50 years of age.