A screening test is being researched that shows great promise for reducing the death rate from ovarian cancer. Results from a 14-year-long study of more than 200,000 women in Britain show that the test is beneficial, but more study will need to be done to see if these findings hold up.
Ovarian cancer usually has a bad prognosis because it progresses quickly and because it often goes undetected until it has spread. Only about 45% of women with ovarian cancer are still alive 5 years after their diagnosis. Screening tests such as the test for CA125 (a blood marker) or ultrasound exams produce too many false positive results to be considered very useful.
This new test is a variation on CA125, but instead of simply measuring levels of this marker, researchers developed a formula that takes into account the degree of change over time and the woman's age to produce a risk score called the Risk of Ovarian Cancer Algorithm.
The study enrolled British women ages 50 to 74 who had an average risk of ovarian cancer. Enrollment occurred between 2001 and 2005. The women were randomly assigned to three groups. About half were assigned to a control group that received no screening. About a quarter of the other women were given CA125 tests using the algorithm. Another quarter had ultrasound scans of their ovaries once a year. Further tests were done if there were suspicious results.
The women were followed through December 2014 for a median of just over 11 years. The first analysis found fewer deaths from ovarian cancer in both the CA125 and ultrasound groups, but the differences were not statistically significant. But a second analysis that excluded women who were diagnosed with ovarian cancer shortly after they entered the study found 20% fewer deaths in the women screened with the algorithm. More analysis found that the differences in death rates did not emerge until the seventh year of the study.
The researchers say that 641 women would have to be screened annually for 14 years to save one life and that for each ovarian cancer detected, 2.2 women had healthy ovaries removed, but said that this rate should be considered low.
The study was published in The Lancet.