A simple, widely available blood test given by GPs can accurately tell women they are at risk of ovarian cancer – as well as flagging up other ‘hidden’ tumours in the pancreas, bowel and lungs.
The test measures levels in the blood of a protein called cancer antigen 125, or CA125, found on the surface of some cancers. Exactly what a raised level means hasn’t been clear – until now.
CA125 tests have been routinely given for 15 years to women with symptoms such as abdominal pain and bloating, changes in appetite and toilet frequency.
However, a raised CA125 reading alone hasn’t been felt reliable enough to provide a clear indicator of ovarian cancer as it can also be a result of conditions such as endometriosis, fibroids and even pregnancy.
Investigations to rule out other causes of symptoms can take months and if ovarian cancer is eventually found to be present, vital treatment may have been delayed.
Now a landmark analysis has shown the test alone can be used to accurately stratify ovarian cancer risk, should a woman see her GP complaining of abdominal symptoms.
Those with levels above a certain threshold will now be fast-tracked for urgent investigations, including an ultrasound scan, for a definitive diagnosis.
One woman to have benefited from a CA125 test is Fiona Barve, 56, a biology teacher from Cambridge (pictured with her daughter Maeve and husband Kiran)
‘This test is already available and widely used by GPs,’ said Professor James Brenton, who researches the disease at the Cancer Research UK Cambridge Institute. ‘But until now, perhaps a raised level meant cancer, perhaps not. The new study gives a more precise framework, so a specific level means a specific percentage risk of ovarian cancer, as well as other cancers. This will help doctors realise when women need a more rapid referral.’
Ovarian cancer strikes 7,400 women each year and is the cause of more than 4,000 deaths a year.
Swift diagnosis is key to successfully treating it – nine in ten women with early-stage disease survive it. If picked up at a late stage, just one in ten live more than five years.
At present, around a third of women are diagnosed early with the majority only spotted at later stages – partly due to the fact that ovarian cancer often causes few distinct symptoms until it is advanced.
In 2011, the National Institute for Health and Care Excellence recommended that GPs test women with symptoms of possible ovarian cancer for CA125. But the new study has been said to give the test ‘more power’, and is particularly helpful for flagging up problems in women over the age of 50.
Initial studies involved giving it to women already known to have ovarian cancer – a common method used by researchers to work out if a test really works. But doctors never had a clear picture of exactly what a specific reading meant and research efforts focused on finding new tests that might provide a more accurate result.
The new study looked at 50,000 women who had seen their GP complaining of symptoms and were given the CA125 test.
One in ten of women with levels above a certain threshold went on to be diagnosed with ovarian cancer, making an abnormal test 12 times more predictive than previous estimates had suggested.
This study showed for the first time that an abnormal CA125 result in primary care was not only associated with ovarian cancer, it also found more than 380 women with an abnormal CA125 result had another type of cancer such as pancreatic, lung or bowel cancer.
Age was a big factor that affected the results. The proportion of women with an abnormal test who had any cancer was much higher in women aged 50 or over.
One woman to have benefited from a CA125 test is Fiona Barve, 56, a biology teacher from Cambridge. She began suffering stomach pain in 2017. ‘Because of my age, I just thought I was menopausal,’ says the married mother of one, adding: ‘I was a bit more tired than usual but as a full-time teacher that goes with the job.’
When the tiredness and pain didn’t disappear, she visited her GP who carried out blood tests.
‘A few days later, she asked me to come in,’ says Fiona. ‘My levels of CA125 were raised and she booked me in for an ultrasound within a week.’
Scans revealed a growth in her pelvis. Within four weeks of her initial CA125 test, Fiona was undergoing surgery to remove her reproductive organs and part of her liver, where the cancer had spread.
She finished chemotherapy in February 2018 and then began having infusions of bevacizumab, a drug that blocks tumour growth.
In March 2019, she finished all treatment, but still has a CA125 test every three months. ‘My levels are low, so they don’t think I have cancer at this time,’ she says.
She believes she owes her life to the CA125 test and adds: ‘God knows where I’d be if things had been left any longer.’