UK Collaborative Trial of Ovarian Cancer Screening

Does screening for ovarian cancer help save lives by detecting the disease earlier?

What was this study about?

Ovarian and tubal cancers are the leading cause of death from gynaecological cancers in the UK. Most women are diagnosed with advanced stage disease which is associated with poor survival. UKCTOCS was a multi-centre randomised controlled trial that evaluated whether it would be possible to save lives of women diagnosed with ovarian and tubal cancer in the average-risk population by using screening to detect the disease earlier, when treatments are more effective.

Two forms of annual screening were tested:

  • (i) multimodal screening (MMS) using blood tests to assess changes in the serial profile of a cancer biomarker called CA125 followed by transvaginal (internal) ultrasound in those where the test was not normal
  • (ii) ultrasound screening (USS) using transvaginal ultrasound scan.

Women in the screen arms underwent 7-11 annual screens. All women were followed up through national cancer and death registries to assess if they had developed ovarian cancer or died of the disease.


What difference did this study make?

UKCTOCS is the largest ovarian cancer screening trial to date.

Screening in UKCTOCS did not reduce deaths due to ovarian and tubal cancer. However, there was robust evidence that multimodal screening can detect ovarian cancer, especially the most common and aggressive type (high grade serous ovarian cancer) earlier and improve short term outcomes. Additionally, the trial showed that looking at changes in an individual’s cancer biomarker levels over time can improve the performance of the screening test and that ultrasound scans cannot detect early tubal cancers.

While the trial findings do not support ovarian cancer screening using CA125 and ultrasound, it suggests that novel approaches that can detect more women earlier in the course of the disease are likely to reduce deaths.

The trial biobanks with over half a million samples provide the opportunity to evaluate novel biomarkers and are being used in a large number of secondary studies on early detection of cancer. In addition, the design, conduct and analysis of UKCTOCS has generated insights into all aspects of large-scale screening trials that span decades.

Type of study

Randomised trial

Contact details

Data Sharing

UKCTOCS Longitudinal Women’s Cohort (UKLWC) is the bioresource created in the course of UKCTOCS. The women provided consent for use of data and samples as part of research collaborations involving ethically approved secondary studies. Please find more information at Please email Dr Sophia Apostolidou ( if you wish to explore collaborations.

Who funded the study?

UKCTOCS was funded by Medical Research Council, National Institute for Health Research, Cancer Research UK and The Eve Appeal.

When did it take place?

The trial started in April 2001 and recruited women until September 2005. The women randomised to the screening arms underwent yearly screening until December 2011. Women were followed up initially until December 2014 and then until June 2020.

Papers with the main results were published in The Lancet in December 2015 and June 2021. A detailed summary of the entire trial was published in Health Technology Assessment in May 2023.

Where did it take place?

The study was set up and initially coordinated from St Bartholomew’s Hospital (Barts) at Queen Mary University London (2000-2004) and then from University College London (UCL) (2004-2020). Other organisations involved included University of Sussex (Psychosocial), St George’s Hospital (Ultrasound screening), Massachusetts General Hospital (Multimodal screening) and LSE (Health Economics).

Women were recruited and screened at 13 centres in England, Wales and Northern Ireland:
• Queen Elizabeth Hospital, Gateshead
• St. Bartholomew’s Hospital, London
• Liverpool Women’s Hospital, Liverpool
• Nottingham City Hospital, Nottingham
• St. Mary’s Hospital, Manchester
• Derby City Hospital, Derby
• Royal Free Hospital, London
• St. Mary’s Hospital, Portsmouth
• St. Michael’s Hospital, Bristol
• Belfast City Hospital, Belfast
• University of Wales College of Medicine, Cardiff
• Llandudno Hospital, Llandudno North Wales
• James Cook University Hospital, Middlesbrough

Who was included?

202,638 postmenopausal women from the general population, aged 50-74 years with at least one ovary, no past history of ovarian cancer, and no family history suggestive of increased risk of ovarian cancer.