New findings from the world’s biggest ovarian cancer screening trial, which included more than 200,000 women over 14 years, suggest that a yearly blood test might reduce the number dying from the disease by around 20%.

The ROCA screening blood test interprets changing levels of the blood protein CA125, which is linked to ovarian cancer, over time, providing a much more tailored picture of individual risk than the one-off blood test measuring a fixed ‘cut-off’ point.

Using this test, the UK Collaborative Trial of Ovarian Cancer Screening (UKCTOCS), led by researchers at University College London, showed a delayed effect on mortality compared with control arms, with the difference becoming significant after the first seven years. 

Early results, published in The Lancet, suggest estimates of death reduction attributable to ovarian cancer screening ranging from 15% to 28%. But study lead Ian Jacobs has stressed that further follow-up is needed for “greater confidence about the precise reduction in mortality which is achievable,” noting that it is possible that the mortality reduction could be “greater or less than these initial estimates”.

Given the uncertainty still surrounding the data, Cancer Research UK says is doesn’t think there’s enough evidence for the NHS to introduce a national screening programme at this stage.

Whether population screening is effective depends on a range of factors including further follow-up and health economic analyses. In the meantime, efforts can be made to refine ovarian cancer screening, develop tests with greater sensitivity and more lead time and improve ways to risk stratify the population, the researchers note.