04/08/2026
The CA 125 blood test remains the most widely used marker for ovarian cancer. Previously a positive result was fixed at 35 IU/ml or above regardless of age.
However, following new research, the fixed figure was shown to be missing cancers in older women while triggering unnecessary investigations in younger ones
NICE (The uk government health body) has now released new guidance on how CA125 test results should be interpreted.
Ovarian cancer is the 6th most common cancer in women in the UK, with around 7,000 new cases every year, and it is estimated that 1 in 50 UK females will be diagnosed with ovarian cancer in their lifetime. It causes around 4,100 deaths a year, making it a more frequent cause of death than cancers of the uterus or cervix.
CA125 is a protein which can be found on the surface of most ovarian cancer cells. Levels tend to be higher in women with ovarian cancer than in women without it, which makes CA125 a useful tumour marker, and remains the most widely used marker for ovarian cancer.
In March 2026, NICE issued new guidelines recommending that the threshold for reporting a positive CA125 test result should be determined by age, similar to how PSA values (A test to screen for Prostate Cancer in men) are currently interpreted.
You can read more about this in our article on our website.