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New cervical cancer test outperforms existing tests

The epigenetic cervical cancer test detected more cancers than Pap smears and the HPV test

Ingrid Torjesen

Tuesday, 18 December 2018

A new test for cervical cancer detected all cancers in a trial* of 15,744 women, published in the International Journal of Cancer, outperforming both the current Pap smear and human papillomavirus (HPV) test.

Screening for cervical cancer using the Pap smear only detects around 50% of cervical pre-cancers. A newer more accurate cervical screening method, which involves testing for the presence of DNA from HPV, the primary but indirect cause of cervical cancer, is now available, but the HPV test only identifies whether or not women are infected with a cancer-causing HPV, but not their actual risks of cancer, which remains quite low. An estimated 10 million women in the UK are infected by HPV, but the majority will eventually clear the virus and not develop the disease, meaning the positive test will cause them unnecessary worry.

The study investigated how well a new 'epigenetics-based' cervical cancer test predicted the development of cervical cancer up to five years in advance compared with the Pap smear and HPV tests in a large study of women aged 25-65 in Canada.

As opposed to checking for patterns in the DNA genetic code itself that are indicative of the HPV virus, the new test looks at the naturally-occurring chemical markers that appear on top of the DNA, making up its 'epigenetic profile'.

The new test detected 100% of the eight invasive cervical cancers that developed in the 15,744 women during the trial. In comparison, the Pap smear only detected 25% of the cancers, and the HPV test detected 50%.

Lead researcher Professor Attila Lorincz from Queen Mary University of London, who also helped develop the world's first test for HPV in 1988, said: "This is an enormous development. We're not only astounded by how well this test detects cervical cancer, but it is the first time that anyone has proven the key role of epigenetics in the development of a major solid cancer using data from patients in the clinic. Epigenetic changes are what this cervical cancer test picks up and is exactly why it works so well.

"In contrast to what most researchers and clinicians are saying, we are seeing more and more evidence that it is in fact epigenetics, and not DNA mutations, that drives a whole range of early cancers, including cervical, anal, oropharyngeal, colon, and prostate."

The study also looked more closely at a subset of 257 HPV-positive women which were representatively selected from the large study. The new test detected 93% of pre-cancerous lesions in those women, compared to 86% detected using a combination of the Pap smear and HPV test, and 61% detected using the Pap smear on its own.

Professor Lorincz added: "We were surprised by how well this new test can detect and predict early cervical cancers years in advance, with 100% of cancers detected, including adenocarcinomas, which is a type of cervical cancer that is very difficult to detect. The new test is much better than anything offered in the UK at present but could take at least five years to be established."

The authors say that using this test in the clinic would reduce the number of visits to the doctor and screening appointments, as high-grade disease would be detected from the start. They also say that if it was fully implemented, it would be cheaper than the Pap smear.

*Cook DA, Krajden M, Brentnall AR, et al. Evaluation of a validated methylation triage signature for human papillomavirus positive women in the HPV FOCAL cervical cancer screening trial. IJC, DOI: 10.1002/ijc.31976

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