The UK Collaborative Trial of Ovarian Cancer Screening (UKCTOCS) is a randomised controlled trial of 202,638 women to investigate whether screening for ovarian cancer can save lives. While more women were picked up with earlier stage ovarian cancer with blood based multimodal screening, the trial at this point could not demonstrate that screening saves lives. Further follow up of the women is now underway.

Why was this work needed?

Identifying ovarian cancer early is difficult because the symptoms are often seemingly minor and difficult to distinguish from other conditions. However, early diagnosis is likely to make a difference to survival. For example, around 90 per cent of women diagnosed with early-stage ovarian cancer will live for five years or more, compared to just three per cent of those diagnosed with late-stage ovarian cancer. This is the reason for trying to screen for ovarian cancer. However, screening can bring harms, so it is very important to establish whether or not ovarian cancer screening could save lives.

What happened?

The UKCTOCS trial recruited more than 200,000 women from across the UK, aged between 50 and 74. It then randomly assigned these women into three groups, a group given no screening, a group given an annual ultrasound and a group given an annual blood test, and follow up ultrasound if needed. The women were followed for an average of eleven years to see what happened to them.

What were the benefits?

More women were picked up with earlier stage ovarian cancer with screening compared to women who had no screening. However, at this point, the evidence from UKCTOCS does not show that screening reduces the deaths from ovarian cancer. Research has also shown that screening for ovarian cancer carries its own risks, including psychological distress and unnecessary surgery for women who do not have ovarian cancer but receive an incorrect or unclear diagnosis. Further follow up of the women is now underway. Meanwhile more research is needed into how ovarian cancer develops and progresses to help inform any future interventions. 

What type of data was involved?

In order to invite women to participate in the trial, the researchers identified people from age and gender registers held by the health authority. Specialised software developed by the NHS was then used to randomly select individuals, their contact details and their GP practice. This was shared with the trial coordinating centre so that they could be invited to participate.

Access to contact details of individuals who were sent invitations between 2001-2005 was with approval of the Caldicott Guardians of the individual participating Primary Care Trusts under the article 251 exemption. Subsequently, all participants who joined the trial provided written consent allowing access to medical records and follow up through linkage using their names and NHS numbers to cancer and death registries. In 2015, due to the long period since initial consent, additional approval was obtained from the Confidentiality Advisory Group (CAG) and the Health Research Authority (HRA) for continued follow-up through NHS Digital.

Who funded and collaborated on this work?

UKCTOCS was funded by the Medical Research Council, Department of Health, Cancer Research UK and the Eve Appeal.

Where can I go for more information?

Long term impact of screening on ovarian cancer mortality in the UK Collaborative Trial of Ovarian Cancer Screening