A new screening method can detect ovarian cancer in twice as many women as conventional strategies, according to the latest results from the largest trial of its kind. The findings were published in the Journal of Clinical Oncology (2015; doi:10.1200/JCO.2014.59.4945).
The method uses a statistical calculation to interpret changing levels in women’s blood of a protein called CA125, which is linked to ovarian cancer. This gives a more accurate prediction of a woman’s individual risk of developing cancer, compared to the conventional screening method which uses a fixed ‘cut-off’ point for CA125.
The new method detected cancer in 86% of women with invasive epithelial ovarian cancer (iEOC), whereas the conventional test used in previous trials or in clinical practice would have identified the cancer in fewer than half of these women (41% or 48%, respectively).
The results come from analysis of one arm of the United Kingdom Collaborative Trial of Ovarian Cancer Screening (UKCTOCS), the world’s largest ovarian cancer screening trial, led by University College London and funded by the Medical Research Council, Cancer Research UK, Department of Health, and The Eve Appeal.
The trial involved 202,638 postmenopausal women age 50 years or older who were randomly assigned to two different annual screening strategies (multimodal screening or transvaginal ultrasound) or no test at all.
The study evaluated 46,237 women who continued to attend annual multimodal screening following the first screen. Their blood was tested once a year for CA125 levels and then a computer algorithm was used to interpret their risk of ovarian cancer based on factors including the woman’s age, the original levels of CA125, and how that level changed over time. The serial pattern was compared with known cases of cancer and controls to estimate the risk of having ovarian cancer.
“There is currently no national screening program for ovarian cancer, as research to-date has been unable to provide enough evidence that any one method would improve early detection of tumors,” said Professor Usha Menon, MD, UKCTOCS co-principal investigator and trial coordinator at UCL, who has led the implementation of this 14-year trial. “These results are therefore very encouraging. They show that use of an early detection strategy based on a woman’s CA125 profile significantly improved cancer detection compared to what we’ve seen in previous screening trials.
Previous large ovarian cancer screening trials have used a fixed cut-off for CA125 (more than 35 U/mL) to identify a possible abnormality. But some women can have much higher levels and not have the cancer, while others with levels below this threshold could be harboring the disease.
A total of 640 women in the MMS group had surgery for suspected cancer, of whom 133 women had iEOC. A further 22 women were diagnosed with iEOC within a year of the last annual screen. Results of screening in the ultrasound arm and the impact of screening on ovarian cancer deaths are anticipated later this year.