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Randomized Controlled Trial
. 2025 May;29(10):1-93.
doi: 10.3310/BHBR5832.

Mortality impact, risks, and benefits of general population screening for ovarian cancer: the UKCTOCS randomised controlled trial

Usha Menon  1 , Aleksandra Gentry-Maharaj  1 , Matthew Burnell  1 , Andy Ryan  1 , Jatinderpal K Kalsi  2   3 , Naveena Singh  4 , Anne Dawnay  5 , Lesley Fallowfield  6 , Alistair J McGuire  7 , Stuart Campbell  8 , Steven J Skates  9 , Mahesh Parmar  1 , Ian J Jacobs  10 ; UKCTOCS team
Affiliations
Randomized Controlled Trial

Mortality impact, risks, and benefits of general population screening for ovarian cancer: the UKCTOCS randomised controlled trial

Usha Menon et al. Health Technol Assess. 2025 May.

Abstract

Background: Ovarian and tubal cancers are lethal gynaecological cancers, with over 50% of the patients diagnosed at advanced stage.

Trial design: Randomised controlled trial involving 27 primary care trusts adjacent to 13 trial centres based at NHS Trusts in England, Wales and Northern Ireland.

Methods: Postmenopausal average-risk women, aged 50-74, with intact ovaries and no previous ovarian or current non-ovarian cancer.

Interventions: One of two annual screening strategies: (1) multimodal screening (MMS) using a longitudinal CA125 algorithm with repeat CA125 testing and transvaginal scan (TVS) as second line test (2) ultrasound screening (USS) using TVS alone with repeat scan to confirm any abnormality. The control (C) group had no screening. Follow-up was through linkage to national registries, postal follow-up questionnaires and direct communication with trial centres and participants.

Objective: To assess comprehensively risks and benefits of ovarian cancer screening in the general population.

Outcome: Primary outcome was death due to ovarian or tubal cancer as assigned by an independent outcomes review committee. Secondary outcomes included incidence and stage at diagnosis of ovarian and tubal cancer, compliance, performance characteristics, harms and cost-effectiveness of the two screening strategies and a bioresource for future research.

Randomisation: The trial management system confirmed eligibility and randomly allocated participants using computer-generated random numbers to MMS, USS and C groups in a 1:1:2 ratio.

Blinding: Investigators and participants were unblinded and outcomes review committee was masked to randomisation group.

Analyses: Primary analyses were by intention to screen, comparing separately MMS and USS with C using the Versatile test.

Results: 1,243,282 women were invited and 205,090 attended for recruitment between April 2001 and September 2005.

Randomised: 202,638 women: 50,640 MMS, 50,639 USS and 101,359 C group.

Numbers analysed for primary outcome: 202,562 (>99.9%): 50,625 (>99.9%) MMS, 50,623 (>99.9%) USS, and 101,314 (>99.9%) C group.

Outcome: Women in MMS and USS groups underwent 345,570 and 327,775 annual screens between randomisation and 31 December 2011. At median follow-up of 16.3 (IQR 15.1-17.3) years, 2055 women developed ovarian or tubal cancer: 522 (1.0% of 50,625) MMS, 517 (1.0% of 50,623) USS, and 1016 (1.0% of 101314) in C group. Compared to the C group, in the MMS group, the incidence of Stage I/II disease was 39.2% (95% CI 16.1 to 66.9) higher and stage III/IV 10.2% (95% CI -21.3 to 2.4) lower. There was no difference in stage in the USS group. 1206 women died of the disease: 296 (0.6%) MMS, 291 (0.6%) USS, and 619 (0.6%) C group. There was no significant reduction in ovarian and tubal cancer deaths in either MMS (p = 0.580) or USS (p = 0.360) groups compared to the C group. Overall compliance with annual screening episode was 80.8% (345,570/420,047) in the MMS and 78.0% (327,775/420,047) in the USS group. For ovarian and tubal cancers diagnosed within one year of the last test in a screening episode, in the MMS group, the sensitivity, specificity and positive predictive values were 83.8% (95% CI 78.7 to 88.1), 99.8% (95% CI 99.8 to 99.9), and 28.8% (95% CI 25.5 to 32.2) and in the USS group, 72.2% (95% CI 65.9 to 78.0), 99.5% (95% CI 99.5 to 99.5), and 9.1% (95% CI 7.8 to 10.5) respectively. The final within-trial cost-effectiveness analysis was not undertaken as there was no mortality reduction. A bioresource (UKCTOCS Longitudinal Women's Cohort) of longitudinal outcome data and over 0.5 million serum samples including serial annual samples in women in the MMS group was established and to date has been used in many new studies, mainly focused on early detection of cancer.

Harms: Both screening tests (venepuncture and TVS) were associated with minor complications with low (8.6/100,000 screens MMS; 18.6/100,000 screens USS) complication rates. Screening itself did not cause anxiety unless more intense repeat testing was required following abnormal screens. In the MMS group, for each screen-detected ovarian or tubal cancer, an additional 2.3 (489 false positives; 212 cancers) women in the MMS group had unnecessary false-positive (benign adnexal pathology or normal adnexa) surgery. Overall, 14 (489/345,572 annual screens) underwent unnecessary surgery per 10,000 screens. In the USS group, for each screen-detected ovarian or tubal cancer, an additional 10 (1630 false positives; 164 cancers) underwent unnecessary false-positive surgery. Overall, 50 (1630/327,775 annual screens) women underwent unnecessary surgery per 10,000 screens.

Conclusions: Population screening for ovarian and tubal cancer for average-risk women using these strategies should not be undertaken. Decreased incidence of Stage III/IV cancers during multimodal screening did not translate to mortality reduction. Researchers should be cautious about using early stage as a surrogate outcome in screening trials. Meanwhile the bioresource provides a unique opportunity to evaluate early cancer detection tests.

Funding: Long-term follow-up UKCTOCS (2015-2020) - National Institute for Health and Care Research (NIHR HTA grant 16/46/01), Cancer Research UK, and The Eve Appeal. UKCTOCS (2001-2014) - Medical Research Council (MRC) (G9901012/G0801228), Cancer Research UK (C1479/A2884), and the UK Department of Health, with additional support from The Eve Appeal. Researchers at UCL were supported by the NIHR UCL Hospitals Biomedical Research Centre and by MRC Clinical Trials Unit at UCL core funding (MR_UU_12023).

Keywords: CA-125 ANTIGEN; CANCER SCREENING; EARLY DETECTION OF CANCER; GENERAL POPULATION; OVARIAN CANCER; OVARIAN EPITHELIAL CARCINOMA; OVARIAN NEOPLASMS; RANDOMISED CONTROLLED TRIAL; RCT; TRANSVAGINAL ULTRASOUND; UKCTOCS; ULTRASONOGRAPHY.

Plain language summary

Most women with ovarian cancer are diagnosed after the disease has spread widely (advanced stage – III and IV) and more than half die within 5 years. We wanted to find out if testing women without symptoms could pick up ovarian cancer at an earlier stage before it has spread beyond the ovaries and tubes and reduce deaths. We also wanted to assess the risks and benefits of such screening. We invited over 1.2 million women living near 13 centres in England, Wales and Northern Ireland. Of them, 202,638 joined the trial. All women were between 50 and 74 and were no longer having periods. They had never been diagnosed with ovarian cancer or were not having treatment for any other cancer. They did not have many relatives with ovarian or breast cancer. The volunteers were placed into one of three groups at random: The blood test group contained 50,640 women who had yearly CA125 blood tests. If these showed a moderate or high chance of ovarian cancer, they had repeat CA125 tests and a scan. The scan group contained 50,639 women who had yearly internal scans of their ovaries and tubes which were repeated if they showed an abnormality. The no-screening group contained 101,359 women. Those in the blood and scan groups had screening every year until December 2011. We sent all women health questionnaires and also, with their permission, received information about them from the national cancer and death registries till mid-2020. Women in the screened groups had an average of eight years of screening. We followed them for approximately 16 years after they had joined the trial. During this period, 2055 women were diagnosed with ovarian and tubal cancer. It was about 1 in 100 women (1%) in all three groups: 522 of 50,625 in the blood group 517 of 50,623 in the scan group 1016 of 101,314 in the no-screening group More women were diagnosed with early-stage cancer and fewer were diagnosed with advanced cancer in the blood group compared to the no-screening group. There was no difference in the number diagnosed with early or advanced disease between the scan and no-screening group. Despite this difference, the number of women in each group who died from ovarian and tubal cancer was similar in all three groups: 296 of 50,625 (0.6%) in the blood group, 291 of 50,623 (0.6%) in the scan group and 619 of 101,314 (0.6%) in the no-screening group. Other results showed: Overall, 81% women in the blood group and 78% in the scan group attended all of their annual screening appointments. In the blood group, screening detected 84% of ovarian and tubal cancers diagnosed within one year of the test and correctly classified as normal 99.8% of women who did not have ovarian and tubal cancer. In the scan group, screening detected 72% of ovarian and tubal cancers diagnosed within one year of the last test and correctly classified 99.5% of those who did not have ovarian and tubal cancer. Both screening tests were associated with minor complications. While screening did not increase anxiety, there was slightly increased worry in women who were asked to return for more intense repeat testing. Both screening methods picked up changes that were in fact not ovarian cancer. This meant that women had unnecessary surgery together with the worry and risk of complications that go with it. In the blood group 14 women had unnecessary surgery for every 10,000 women screened annually. This means that for each woman found to have ovarian cancer, an additional 2 women had unnecessary surgery. In the scan group 50 women had unnecessary surgery for every 10,000 women screened annually. This means that for each woman found to have ovarian cancer, an additional 10 women had unnecessary surgery. A biobank with all the donated data and over 0.5 million serum samples, including yearly samples from women in the blood group, was built and continues to be used in many new studies, mainly focused on early detection of cancer. Screening using the CA125 blood test or transvaginal ultrasound scan to test for ovarian cancer did not save lives. Additionally, it was associated with some harm. Therefore, an ovarian cancer screening programme for most women cannot be currently recommended. The trial also showed for the first time that ovarian cancer can be detected earlier through screening. However, for screening to save lives, the test needs to pick up many more women earlier in the course of the disease so that available treatments are effective. The biobank provides an opportunity for scientists to see if newer tests for cancer can detect the disease earlier.

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