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New research confirms the importance of CA125 blood tests in diagnosing ovarian cancer in primary care

02 November 2020

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What have they found?

A team of researchers at the University of Cambridge, Manchester and Exeter are the first to provide evidence that the already established CA125 blood test for ovarian cancer is an effective diagnostic tool in the primary care setting.

Primary care is the first point of contact to the healthcare system accessed directly by the public, for example your GP or a community nurse. Secondary care is hospital services and specialist clinics such as surgery and imaging, which can only be accessed through referral from primary care.

Around 7,400 women are diagnosed with ovarian cancer in the UK each year, with the majority of cases diagnosed at a late stage, through emergency presentation, such as a visit to A+E. 

Early diagnosis is key to helping women to survive the disease and this research has confirmed that performing a CA125 blood test when a woman first presents symptoms to her GP, is an inexpensive and effective tool to detect ovarian cancer in its earliest stages.

What does this research add to what we already know about the CA125 test?

The efficacy of a CA125 test has been extensively evaluated when used at hospitals and specialist clinics, but little was previously known about its diagnostic performance when used by GPs, where most patients with ovarian cancer first present.

The study, funded by Cancer Research UK and the National Institute for Health Research, shows that the test is more predictive than originally thought and a useful tool for GPs to diagnose ovarian and other cancers. The team also looked at the participants CA125 levels and age to develop individualised risk scores. Estimating the probability of ovarian cancer this way would help clinicians to make decisions on further referral and investigation. 

The findings also showed that a significant proportion of women with an abnormal result had other cancers. This new insight suggests that clinicians should consider other cancers besides ovarian cancer for women presenting with symptoms

Can this now be used as a screening tool?

Although the research helps to endorse the effectiveness of the CA125 test in helping women and GPs to make individual referral decisions for further investigation, it is not accurate enough to be used as a screening tool. This is because it can be increased by many noncancerous conditions, and also levels can remain normal in up to 50% of women with early stage disease.

What does this mean?

The research helps to endorse the effectiveness of the CA125 test in helping women and GPs to make individual referral decisions for further investigation. The insight provided by this research will help aid the diagnosis pathway for ovarian cancer and also inform guidelines to recommend women for further testing to be made on the basis of cancer probability rather than a single CA125 cutoff.

Whilst this research is good news that CA125 tests are useful in helping GPs diagnose ovarian cancer, OCA-funded researcher Professor Ahmed Ahmed at the University of Oxford is working to better understand how ovarian cancer starts to potentially develop the world’s first ovarian cancer screening tool. Having a screening tool which could help detect precancerous lesions could prevent women from developing ovarian cancer and diagnose women at an earlier stage. 

To find out more about our research click here.