GP requests for CA125 testing in women with symptoms of ovarian cancer have soared by nearly 200%, but the rise is warranted as around one in ten of those with high levels are subsequently diagnosed with malignancy, show UK researchers.
In results described as ‘fanatistic news’ by experts, the study showed GPs made nearly three times as many requests for CA125 testing after NICE recommended the approach.
They also showed that follow-up investigations found around 10% of patients with positive CA125 test results were subsequently diagnosed with ovarian cancer.
NICE published new guidance on diagnosis and management of ovarian cancer in April 2011, in which it recommended GPs should order CA125 testing in women – particular those over 50 – with symptoms of bloating, feeling full quickly, lower abdominal pain and needing to urinate urgently or frequently. Those with CA125 levels over 35 IU/mL should be referred on for ultrasound examination of the pelvis and further investigation if the scan is positive.
At the time there was some concern over what the optimal CA125 threshold for referral should be, with the RCGP calling for greater clarity on when to test for CA125 and how to deal with the results.
But a new study - presented at the European Cancer Conference in Belgium earlier this month - into the impact of CA125 testing at Airedale General Hospital showed the guidance was picking up a substantial proportion of women with ovarian cancer.
Records showed GPs made 1,314 requests for CA125 testing in the six months from May to October 2011, after the NICE guidance came in, compared with 486 in the previous six months from November 2010 to April 2011 – representing a 170% increase in requests.
Seven (8.3%) out of 84 patients with elevated CA125 were subsequently diagnosed with ovarian cancer in the first six months after the recommendations were introduced, as were five (14.7%) out of 34 patients in the next six months.
Lead researcher Dr Michael Crawford told Pulse the results were positive and showed GPs had responded to the guidance, but suggested even more needs to be done to achieve more timely diagnosis, as the women who were diagnosed had very high levels of CA125 (ranging from 166–6,645 IU/mL in the first phase and 268–2,344.7 IU/mL in the second).
Dr Crawford said: ‘Those patients that were diagnosed because they had come through the NICE approach, with blood tests and ultrasounds, actually had quite high CA125s, with quite advanced disease.
‘I think for this process therefore to have a significant impact on the timeliness of diagnosis is going to require GPs to do a lot more CA125 testing than they are doing and thinking about it even more.’
Dr Crawford added that GPs needed to be given more information and encouragement to take up testing.
‘I think we need to have publicity drive to encourage people to do it, but as part of a clear study so we monitor clearly before and after what the impact has been, looking at how the pattern of diagnosis changes. It’s a matter of showing you really can make a difference in the population.’
Professor William Hamilton, professor of primary diagnostics at the Peninsular Medical School in Exeter, said the results were ‘fantastic news’ and suggested NICE has ‘hit the nail on the head’ with the CA125 recommendation.
He told Pulse: ‘This is fantastic news. The PPV of a positive CA125 (>35) was around 10% (two samples giving 8.3% and 14.7%). Better still not all false positives were truly “false” – in that almost as many non-ovarian cancers were identified, plus much benign pathology.
‘PPVs of symptoms alone are much smaller – so the CA125 definitely adds to symptoms and greatly improves the assessment of risk.’
Professor Hamilton added: ‘Labs were worried that they would be swamped by hundreds of “unnecessary” tests, and that GPs would use CA125 tests indiscriminately. On the contrary, GPs seem to be using tests very sensibly – a hit rate of nearly 10% compares very favourably to, say, full blood counts or thyroid function tests.
‘It’s also very useful for NICE – they had effectively no primary care data to guide them and it looks as if they hit the nail on the head.’
European Cancer Congress 2013; Amsterdam, 27 September – 1 October: Abstract no. 3098
