Normal Risk Ovarian Screening Study: Long-Term Update

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As reported in the Journal of Clinical Oncology by Han et al, the 21-year update of the Normal Risk Ovarian Screening Study (NROSS) has shown that the NROSS screening strategy remains effective for the detection of ovarian cancer and detection at early disease stages.

Study Details  

The NROSS study examined a screening strategy in postmenopausal women at conventional hereditary risk for ovarian cancer: significantly increasing serum CA125 prompted transvaginal sonography (TVS), and abnormal TVS prompted surgery to detect ovarian cancer. Overall, 7,856 healthy postmenopausal women were screened annually, for a total of 50,596 woman-years.

Serum CA125 was analyzed by the Risk of Ovarian Cancer Algorithm (ROCA) each year. Women for whom risk was unchanged and less than 1:2,000 returned for subsequent CA125 analysis in 1 year. If risk increased above 1:500, TVS was performed immediately; if risk was intermediate, CA125 was repeated in 3 months, with further increase in risk above 1:500 triggering referral for TVS.

Key Findings

Overall, an average of 2% of participants were referred to TVS annually. Over 21 years of follow-up, 34 women were referred for surgery, with detection of invasive ovarian cancer in 15 and borderline tumors in 2. Of the 17 tumors detected, 12 were stage I/II. In addition, a total of seven endometrial cancers were detected, with six detected at stage I.

The findings for ovarian cancer yielded a positive predictive value of 50% (17/34; 95% confidence interval [CI] = 32.4%–67.6%). For all cancers, the screening strategy had a positive predictive value of 74% (25/34). These values exceeded the predefined minimum acceptable positive predictive value of 10%.

A total of four ovarian cancers and two borderline tumors were diagnosed with a normal ROCA, yielding a sensitivity for detecting ovarian and borderline cancer of 74% (17/ 23); 70% of ROCA-detected cases (12/17) were stage I to II.

Compared with the UK Collaborative Trial of Ovarian Cancer Screening (UKCTOCS) control group, the NROSS strategy reduced diagnosis of stage III to IV ovarian cancer by 34%. Compared with U.S. Surveillance, Epidemiology, and End Results (SEER) data for 2004 to 2019 (including both ovarian cancers and serous borderline tumors), the NROSS strategy reduced diagnosis at stage III to IV by 30%.

The investigators concluded, “While the NROSS trial was not powered to detect reduced mortality, the high specificity, positive predictive value, and marked stage shift support further development of this strategy.”

Robert C. Bast Jr, MD, of the Department of Experimental Therapeutics, The University of Texas MD Anderson Cancer Center, is the corresponding author for the Journal of Clinical Oncology article.

Disclosure: The study was funded by the National Cancer Institute and others. For full disclosures of the study authors, visit

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