Whether screening for ovarian cancer saves lives is still unclear despite large trialBMJ 2015; 351 doi: http://dx.doi.org/10.1136/bmj.h6876 (Published 18 December 2015) Cite this as: BMJ 2015;351:h6876
A trial of more than 200 000 UK women has provided no definite answer as to whether screening for ovarian cancer saves lives. Longer follow-up studies are needed to decide whether testing the general population is cost effective, the researchers said.1
Ovarian cancer continues to be diagnosed at an advanced stage, and 60% of patients die within five years of diagnosis. The United Kingdom Collaborative Trial of Ovarian Cancer Screening (UKCTOCS) tested the hypothesis that screening for ovarian cancer in the general population can reduce deaths from the disease without causing significant harm.
The researchers recruited 202 638 women aged 50-74 from 2001 to 2005 through 13 trial centres in England, Northern Ireland, and Wales and randomised them to no screening (101 299 women analysed), yearly screening using serum CA125 plus a transvaginal ultrasound scan as a second line test (“multimodal” group, 50 624), or yearly screening with transvaginal ultrasound (“USS” group, 50 623).
The findings, reported in the Lancet, showed that, during the 14 year trial, ovarian cancers were diagnosed in 630 women who had no screening, 338 women in the multimodal group, and 314 women in the USS group.1
Overall deaths from ovarian cancer were not significantly different between the women who were not screened and those in either of the screening groups. But further analysis showed that deaths did fall significantly after seven years of screening, with a relative reduction of 23% in the multimodal group (95% confidence interval 1% to 46%) and 21% in the USS group, when compared with no screening.
The results also showed that cancer was detected at an earlier stage in women who were screened. Altogether, 39% of women (118 of 299) who had multimodal screening had their cancer detected an early stage, compared with 26% of those who were not screened (148 of 574) (P<0.0001).
The preliminary estimate of the number needed to screen in the multimodal group to prevent one ovarian cancer death after 14 years was 641. For every three women who had surgery as a result of an abnormal screen one woman had ovarian cancer, while two women did not. Among those who had surgery around 3% had major complications.
Ian Jacobs, of the Institute for Women’s Health at University College London, UK, the University of New South Wales in Sydney, Australia, and the University of Manchester, UK, led the study. He said, “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.”
Commenting on the study René Verheijen and Ronald Zweemer, of UMC Utrecht Cancer Center in the Netherlands, wrote,2 “If only 59% of ovarian cancer cases are detected by screening plus ultrasound, we will need to focus on why and how screening—as undertaken within UKCTOCS—still has a significant, but delayed, survival effect.
“Trying to unravel the mechanism behind this effect so that it can be improved should have high priority . . . Awareness and symptom recognition for diagnosis of cancer at an early stage will be difficult to improve upon.”
They added, “Screening will not be warranted until the UKCTOCS outcome has been validated in daily practice. But careful studies such as that of Jacobs and colleagues show that we must and can focus on mechanisms of early cancer detection.”
Cite this as: BMJ 2015;351:h6876