Testing for a specific protein in the blood could help doctors to spot ovarian cancer, as well as other cancers, researchers will say today.
Dr Garth Funston, a clinical research fellow at the University of Cambridge, England, will tell delegates at the 2019 NCRI Cancer Conference in Glasgow that testing for levels of CA125 could help women and their GPs to decide if more invasive tests are needed to check for ovarian and other cancers.
This is the first large study to look at how well CA125 testing performs in general practice in women who have possible symptoms of ovarian cancer.
The researchers say their findings mean that clinical guidelines could now be improved to ensure urgent referrals are made for women most at risk.
“Less than half of women with ovarian cancer survive for five years following diagnosis. The majority of women are not diagnosed until the disease is advanced, which makes it more difficult to cure,” said Dr Funston.
“It’s important that GPs have effective tools to detect ovarian cancer early and ensure patients are referred appropriately. While CA125 is widely used in general practice in the UK and internationally, prior to this study, it was unclear how effective a test it really was in general practice.”
The research comprised data on 50,780 women who visited GPs in England with possible signs of ovarian cancer and were tested for levels of CA125 in their blood between May 2011 and December 2014.
The blood test results were compared with data on which women were diagnosed with ovarian cancer or another form of cancer in the 12 months following their blood test.
The researchers found that 10% of women who had an abnormally high level of CA125 in their blood were found to have ovarian cancer – higher than previously thought and ten times higher than the estimate in the UK’s 2011 NICE guidelines on ovarian cancer diagnosis.
In women who had abnormal test results and were aged 50 years or older, 15% were found to have ovarian cancer, while in women under 50 with high CA125 levels, only 3% were diagnosed with ovarian cancer.
About 17% of women over the age of 50 who had received an abnormal result were diagnosed with another form of the disease, such as pancreatic, lung or womb cancer.
The large size of the study meant that researchers were, for the first time, able to look in detail at women with different levels of CA125 in their blood in general practice and give more accurate estimates of cancer risk according to those levels.
The NCRI Cancer Conference also heard yesterday that a non-invasive test has been developed that will enable women to collect their own urine and vaginal samples for cervical pre-cancer testing.
Dr Belinda Nedjai, senior research fellow and director of the Molecular Epidemiology Lab at Queen Mary University of London, said the self-sampling test had proven to be popular with women taking part in the study, which meant it was likely to improve participation in cervical cancer screening programmes.
She said it is believed to be the largest study yet to test S5, a methylation classifier, in urine and self-collected cervical samples to detect pre-cancer lesions in women who have been referred for further investigation.
The S5 test measures DNA methylation of four HPV types most strongly associated with cancer – HPV16, HPV18, HPV31 and HPV33 – and the human gene EPB41L3, to produce a score that indicates the level of risk.
If the score is above a selected cut-off, it indicates an increased risk of a pre-cancer lesion, and the higher the score the higher the risk of cancer.
Cervical cancer is preceded by cervical intraepithelial neoplasia (CIN), which is divided into three stages (CIN1, CIN2 and CIN3), with the likelihood of the cells developing into cancer increasing at each stage.
A total of 620 women attending the colposcopy clinic at the Royal London Hospital provided vaginal samples, collected themselves using vaginal swabs, and 503 of these women also provided a urine sample. The researchers extracted and analysed the DNA in the lab and generated S5 scores.
It was found that S5 classifier with or without HPV testing worked well in both urine and vaginal samples, distinguishing between women who had no pre-cancerous lesions and those who had CIN3 or higher lesions.
In urine, S5 was better at correctly identifying women who had pre-cancer lesions than testing for the presence of HPV16 or 18.
96% of true CIN3 were identified with S5 compared to 73% with an HPV16 or 18 test.
Abstract no: Poster 2451. Non-invasive methylation test to detect cervical pre-cancer in self-collected vaginal and urine specimens. Belinda Nedjai.
Abstract number 2931. The predictive value of CA125 for ovarian cancer in General Practice: a population-based cohort study of over 50,000 women. Garth Funston et al.
Abstract number 2935. The incidence of non-ovarian cancers in women with elevated CA125 levels in General Practice. Garth Funston et al.
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