How epigenomic testing could improve cervical cancer detection
Introducing a new epigenomic test as part of routine cervical screening may help clinicians spot the signature of cervical cancer years before it develops
Cervical cancer is responsible for the deaths of around 850 women a year, according to Cancer Research UK, with almost all those incidents being preventable. Researchers from University College London hope that their new test, which uses epigenomic testing rather than genomic testing, will help doctors to detect precancerous tissue before it becomes a tumour.
The ‘women’s cancer risk identification-cervical intraepithelial neoplasia’ (WID-CIN) test, whose evaluation was published in Genome Medicine last year, looks at patterns of DNA methylation in cells from the cervix.
- Cervical cancer: Overview and symptoms (NHS.uk)
What is DNA methylation?
Methylation is a type of DNA modification that can guide what genes are expressed in a cell and when. It is an extra layer of information sitting on top of DNA and is included when we talk about the epigenome and epigenomic testing.
This makes the epigenome a possible source of cancer markers for researchers. In some cases, testing the sample’s epigenome may be appropriate because it could help doctors understand if it is precancerous or not. This is what the WID-CIN test taps into. By looking for specific DNA methylation patterns, it can give a clearer picture of what’s going on in the sample’s cells and help inform the doctor and patient on the next steps.
- Further learning: What is epigenomics?
WID-CIN test’s place in cancer screening programmes
The WID-CIN test was validated on samples sourced from the Swedish cervical cytology biobank. Researchers compared their test’s performance against current standard screening methods. They found that their WID-CIN test detected a higher number of samples with more advanced changes.
The test also flagged samples that were taken from patients who did not have detectable precancerous changes using standard screening methods, but who would then develop them in the four years after the sample was taken.
Researchers are now looking for the WID-CIN test to be incorporated into existing cervical screening programmes. “Our approaches to cervical screening must adapt so that programmes continue to deliver benefit,” said University College London professor and lead investigator Professor Martin Widschwendter.
Making the best better?
The current cervical screening programme is the UK’s most successful cancer prevention programme. It is not a direct test for cancer, but can catch precancerous cells before a tumour develops.
The screening programme is a routine and multi-stage affair. During screening, a nurse or doctor take an initial sample of cells from the cervix. In a lab, these cells are tested for human papillomavirus (HPV), which is the cause 99.8% of all cervical cancers. If specific, high-risk types of HPV (that are associated with cervical cancer) are detected, then the cells go on to a second screening stage which looks for abnormal changes. These changes are collectively called cervical intraepithelial neoplasias (CINs). CINs sometimes go on to become cancer, but may also go away on their own. The next steps in the screening programme depend on whether changes are detected and how advanced they are.
Detection is normally done by a trained person examining CINs using imaging equipment, such as a microscope. This is called cytology. It is this screening stage that the researchers hope the WID-CIN test will improve.
Not just cervical cancer
The WID-CIN method could also have applications for early detection of other cancers. “The same cervical sample can also deliver information on a woman’s risk of three other major cancers – breast, ovarian and womb cancers,” said Professor Widschwendter.
For endometrial cancer – a type of cancer starting in the womb – the test was able to correctly identify 97% of patients with cancer from cervical smear test samples. This is according to results published by the same research group in the Journal of Clinical Oncology.
Meanwhile, the breast and ovarian cancer tests results, both published in Nature Communications, identified women with the highest risk of developing these cancers with 25-30% greater accuracy than current methods.
The authors hope that the four tests could be combined into a single screening tool, with Professor Widschwendter noting that including predictive testing in current screening programmes, “offers real potential for cancer prevention in the future”.
