A new screening test that tracks changing levels of a protein in the blood can detect twice as many ovarian cancers as conventional methods, research has shown. The Guardian reports that the technique relies on a statistical calculation to interpret variations in the level of a protein called CA125 which is linked to ovarian cancer. It gives a more accurate prediction of risk than the traditional diagnostic blood test which uses a fixed cutoff point for levels of CA125.
In the world's largest ovarian cancer screening trial, the new method correctly diagnosed 86% of women with invasive epithelial ovarian cancer. The standard test would have been expected to identify fewer than half of these women, according to results from previous studies and clinical practice.
The 14-year UK collaborative trial of ovarian cancer screening led by University College London (UCL) recruited 202,638 post-menopausal women aged 50 and over who were randomly assigned different screening strategies. Professor Usha Menon, the co-principal investigator and trial co-ordinator at UCL, said: "There is currently no national screening programme for ovarian cancer, as research to date has been unable to provide enough evidence that any one method would improve early detection of tumours.
"These results are therefore very encouraging. They show that use of an early detection strategy based on an individual’s CA125 profile significantly improved cancer detection compared to what we’ve seen in previous screening trials.
"The numbers of unnecessary operations and complications were within acceptable limits and we were able to safely and effectively deliver screening for over a decade across 13 National Health Service (NHS) trusts. While this is a significant achievement, we need to wait until later this year when the final analysis of the trial is completed to know whether the cancers detected through screening were caught early enough to save lives."
The study assessed 46,232 trial participants who continued to have regular screening checks after an initial test. Their blood was tested once a year for CA125 levels and a computer programme was used to predict the risk of ovarian cancer based on factors including age, the original level of the protein, and how that level changed over time. The trial’s chief investigator, Professor Ian Jacobs, president of the University of New South Wales in Australia, who helped develop the statistical technique and conceived the trial, said: "CA125 as a biological marker for ovarian cancer has been called into question.
"Our findings indicate that this can be an accurate and sensitive screening tool, when used in the context of a woman’s pattern of CA125 over time. What's normal for one woman may not be so for another. It is the change in levels of this protein that’s important.” Jacobs added that he hoped that “this approach will prove capable of detecting ovarian cancer early enough to save lives".
The trial compared two diagnostic techniques, multimodal screening involving the CA125 blood test and transvaginal ultrasound. Further results from the ultrasound arm of the trial, and the effect of screening on cancer death rates, are expected later this year.
[link url="http://www.theguardian.com/science/2015/may/04/ovarian-cancer-test-trial-women-protein-blood"]Full report in The Guardian[/link]
[link url="http://jco.ascopubs.org/content/31/1/49.abstract?sid=e3b0b46f-eeb7-44c2-a789-8e5fb98b05c2"]Journal of Clinical Oncology abstract[/link]