Regular screening for ovarian cancer could save lives.
Ovarian cancer tends to be diagnosed at an advanced stage, with 60% of patients dying within 5 years.
The United Kingdom Collaborative Trial of Ovarian Cancer Screening (UKCTOCS) is one of the largest ever randomized trials.
Prof. Ian Jacobs, of the Institute for Women's Health ay University College London in the UK, and colleagues hypothesized that ovarian cancer screening in the general population can reduce disease mortality without significant harm, as already seen with other cancers.
Participants were selected from 1.2 million women aged 50-74 years, identified through age/sex registers; 202,638 were recruited between 2001-05 through 13 trial centers across the UK.
Participants were allocated randomly in a 2:1:1 ratio into three groups: 101,299 were not screened, 50,623 had an annual ultrasound scan, and 50,624 underwent annual screening involving a blood test and an ultrasound scan.
Annual screening ended in December 2011 and follow-up was carried out until the end of December 2014 through national cancer/death registries plus questionnaires.
Annual screening reduces mortality in the long term
The median follow-up time was 11.1 years. Ovarian cancers were diagnosed in 630 of the women who had no screening, in 314 of those screened by ultrasound only, and in 338 of those undergoing both blood tests and ultrasound.
Compared with the group that had no screening, from years 0-14, mortality was reduced by 15% among those screened by ultrasound and blood tests and by 11% for those screened by ultrasound only. This represents a relative reduction of 8% in years 0-7 and 23% in years 7-14 in the group screened by blood test and ultrasound, and a reduction of 2% in years 0-7 and 21% in years 7-14 in the ultrasound-only group.
When women who were found to have undiagnosed ovarian cancer on joining the trial were excluded, the average mortality reduction became 20% overall and 28% in years 7-14.
Prof. Jacobs says:
"These results from UKCTOCS provide estimates of the mortality reduction attributable to ovarian cancer screening which range from 15% to 28%. Further follow-up in UKCTOCS will provide greater confidence about the precise reduction in mortality which is achievable. It is possible that the mortality reduction after follow-up for an additional 2-3 years will be greater or less than these initial estimates."
To prevent one ovarian cancer death at 14 years, it is estimated that 641 screenings with ultrasound and blood tests would be necessary.
Regarding the negative impact of screening, out of 10,000 women who underwent blood tests plus ultrasound screening, 14 had unnecessary surgery that resulted in benign pathology or normal ovaries, with a 3.1% rate of major complication.
Ovarian cancer needs more attention
Coauthor Prof. Usha Menon, of the UK's University College London, says that while this shows that screening can reduce ovarian cancer deaths, treatment outcomes for the disease have progressed little in 30 years, suggesting that this area needs attention.
Fast facts about ovarian cancer
- 1 in 4 Americans die of cancer
- 21,980 new diagnoses of ovarian cancer were expected in the US in 2014
- 14,270 women were expected to die of ovarian cancer in 2014.
Moreover, while the relative mortality reduction for the blood test and ultrasound group is 15%, the most significant reduction is for screening between years 7-14, indicating major benefits for long-term screening.
A previous study using UK population data from 2007 showed that for every 1,000 women invited to mammography screening every 2 years for 20 years from age 50, two to three women are prevented from dying of breast cancer.
The authors say that multimodal screening to detect ovarian cancer can alter disease progression and reduce mortality, potentially signaling a new era in ovarian cancer research and care.
They recommend follow-up to find out what the ultimate mortality reduction is and whether it would be cost-effective to screen the general population. Meanwhile, more sensitive screening methods should be developed, they say.
In a linked comment, Prof. René Verheijen and Dr. Ronald Zweemer, of the University Medical Center (UMC) Utrecht Cancer Center in the Netherlands, call for a closer look into the significant, but delayed, survival effect of screening. They also emphasize the need to focus on how cancer can be detected in the early stages.
Medical News Today recently reported on research suggesting that reproductive factors can affect the risk of developing ovarian cancer.