Ovarian Cancer Screening May Save Lives
Since Friday morning Australia time ovarian cancer screening is closer to reality after successful results from the world’s largest ovarian cancer screening trial have been published (1). The authors of the UK study provided first-ever evidence that ovarian cancer screening may save lives.
The largest ever trial in ovarian cancer screening enrolled 200,000 women from 13 UK centres in one of three screening arms and followed them for 14 years. The first group of women (50,000) received yearly ultrasounds while the second group of 50,000 patients had a ROCA test, which includes a yearly CA125 blood test and a transvaginal ultrasound examination if needed. The third and largest group of 100,000 women had no screening. All women were between 50 and 74 years of age.
In the ROCA group an algorithm assessed serum CA125 changes over time rather than using a traditional fixed serum CA125 cut-off of 35 U/ml. The new algorithm integrates results from a transvaginal ultrasound only if the CA125 is abnormally high.
The results in a nutshell
Ovarian cancer was diagnosed in approximately 0.6% of women regardless of the intervention.
Mortality was 0.30% in both screening groups and 0.34% in the no-screening group.
Compared to women who had no screening there was an overall reduction in mortality of 11% in women in the ultrasound group and 15% in women in the CA125 group.
Compared to the no-screening group, ultrasound reduced mortality by 2% in the first 7 years and 21% in the subsequent 7 years.
Similarly, CA125 reduced mortality by 8% in the first 7 years and 23% in the subsequent 7 years.
When women who had undiagnosed ovarian cancer at enrolment into the trial were excluded from analysis, the average reduction in mortality was 20% in the CA125 plus ultrasound group. The reduction in mortality was still 8% in the first 7 years but 28% in the subsequent 7 years.
Overall, only half of ovarian cancers were detected through screening (59% in the CA125 + ultrasound group; 51% in the ultrasound only group). A significant proportion (more than 40%) of ovarian cancers remained undetected.
ROCA (the new CA125 algorithm based on changes of CA125 over time) detects double as many ovarian cancers than the traditional fixed CA125 ((87% vs. 41%).
For every 10,000 women screened for ovarian cancer, 15 ovarian deaths can be prevented.
For every woman who had surgery for a suspicious ovarian mass, which turned out to be ovarian cancer, four women had surgery unnecessarily and no sinister pathology was found.
Why did previous studies fail to demonstrate a benefit of ovarian cancer screening?
One American and one Japanese previous studies published previously failed to report a benefit of ovarian cancer screening. However, these studies were smaller and included a smaller number of women in their respective trials.
Small differences can easily be missed in small research trials and the UK trial had to enrol >200,000 women to show the benefit in the long term follow-up.
How do gynaecological cancer experts around the world interpret the results?
The instant response of many colleagues around the world is that the results from last week’s article are promising and revolutionary because for the very first time in history a benefit of ovarian cancer screening could be demonstrated. However, the benefit appears small and what groups of women will benefit remains unclear.
Further analysis needs to be undertaken to evaluate why 4 of 10 women with ovarian cancer had normal screening tests (when they had proven ovarian cancer). Most gynaecological oncologists believe that the problem “ovarian cancer” is not resolved as yet.
We need more refined tests to reduce the number of women who have false screening tests in both directions:
False negative tests indicating that everything is fine when there is ovarian cancer;
False positive tests wrongly indicating the possibility of ovarian cancer and requiring women to undergo surgery when really they do not have ovarian cancer.
The ROCA test
The ROCA test is licensed to Abcodia Ltd, a UK-based company and is already used in the U.K. by private clinics and in 5 states in the United States. It will become available in additional U.S. states throughout 2016. Australia is not mentioned in the paper.
The ROCA Test uses information obtained through large-scale research about a woman’s age, menopausal status and serial blood CA125 measurements to assess the likelihood that a woman has ovarian cancer. It is the first step in a multimodal assessment for ovarian cancer and will inform a gynaecologist about the woman’s risk of having ovarian cancer.
 Jacobs IJ et al.: Ovarian cancer screening and mortality in the UK Collaborative Trial of Ovarian Cancer Screening (UKCTOCS): a randomised controlled trial. The Lancet, 17 December 2015 (open access).