Ovarian cancer screening picks up earlier stage disease but prognosis remains unchanged

GU cancer

By Michael Woodhead

13 May 2021

The largest ovarian cancer screening trial to date has found no benefit on prognosis from annual serum CA125 measurements or transvaginal ultrasound screening in women aged between 50 and 74.

The UK Collaborative Trial of Ovarian Cancer Screening (UKCTOCS) showed no significant reduction in deaths from ovarian or tubal cancer after 16 years of follow up in more than 100,000 women randomised to  CA125 or transvaginal scans compared to a control group of more than 100,000 women who did not receive screening.

While there was a 10% lower incidence of stage III or IV cancer in the women who underwent multimodal screening (MMS) with CA125 followed by ultrasound compared to the control group, this did not translate into a mortality difference, according to results published in the Lancet.

One of the study co-investigators who led the UK ovarian cancer screening research programme since 1985 was Professor Ian Jacobs, who is now Vice-Chancellor of the University of NSW.

He said the regrettable conclusion was that general population screening for ovarian cancer could not be recommended with either of the screening strategies.

‘“The multimodal screening strategy [CA125] did succeed in detection of ovarian cancer at an earlier stage, but sadly that did not save lives. This is deeply disappointing and frustrating given the hope of all involved that we would save the lives of thousands of women who are affected by ovarian cancer each year,” he said.

“Population screening for ovarian cancer can only be supported if a test is shown to reduce deaths in a future randomised controlled trial. I remain hopeful that a new effective screening test will be found eventually, but it will take many years to conduct a large trial of the test. Realistically, this means we have to reluctantly accept that population screening for ovarian cancer is more than a decade away.”

In the UKCTOCS study women in the MMS group had annual serum CA125 measurements, and were triaged to higher risk monitoring with a  second line transvaginal ultrasound if they showed rising levels.

Women in annual ultrasound group were assessed by a clinician if they had abnormal results.

At a median follow-up of 16·3 years 1% of women in each of the study groups (MSS, ultrasound and no screening) had been diagnosed with tubal or ovarian cancer and there were no differences in the number of women who died of ovarian cancer,  0·6% in each group.

Compared with no screening, there was a 47·2% increase in stage I and 24·5% decrease in stage IV disease incidence in the MMS group.

Overall the incidence of stage I or II disease was 39·2% higher in the MMS group than in the no screening group, whereas the incidence of stage III or IV disease was 10·2% lower.

Professor Jacobs said the study had provided valuable information about the natural history of ovarian cancer and a template for further trials of new screening tests for ovarian cancer.

‘Research does not always give you the results you strive for, but it is never futile. Every stage of this trial brought us closer to understanding ovarian cancer and I take comfort in the knowledge that we have given researchers who take the mantle from the UKCTOCS team a substantial head start.’

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