Cervical cancer self-tests may be key smear alternative – study

This article was taken from: https://www.theguardian.com/society/2019/nov/04/cervical-cancer-self-tests-may-be-key-smear-alternative-study

By Nicola Davis

Swabs or urine self-sampling could be less invasive at identifying high-risk women

Swabs or urine samples taken at home could be as effective at identifying women at high risk of cervical cancer as traditional smear tests, according to new research.

However, self-tests have a drawback – they do not provide cervical cells that can be examined should HPV be found.

Now researchers say a new type of test based on DNA within self-collected urine or swab samples might provide an accurate way to determine whether an HPV-positive woman is likely to have precancerous or cancerous cells.

The study, which is being presented at the National Cancer Research Institute conference in Glasgow and has not yet been published or peer reviewed, involved a test called S5. This detects whether DNA from four types of HPV linked to increased risk of cervical cancer has been modified through a process known as methylation. The test also looks at whether one particular human gene has undergone such changes.

Previous work has shown high levels of methylation at specific sites in such DNA indicates a greater risk of a woman having cells that could turn into cervical cancer, or the presence of cancer itself.

“Some HPV infections will resolve naturally, but the ones that are methylated are less likely to do so,” said Prof Jack Cuzick of Queen Mary University, part of the team behind the work.

To explore the potential of the test, the team focused on 600 women who had already been found to have unusual cells and/or HPV, and had gone to a colposcopy clinic to have their cervix examined.

Each woman was tested for HPV and provided a vaginal swab she had taken herself. Just over 500 of the women also provided a urine sample. DNA was then extracted from the samples and analysed to give an average score for the degree of methylation.

The results reveal that for both urine and vaginal swabs from the women, the S5 test had about a 73% chance of correctly spotting women with advanced abnormal cells as diagnosed by colposcopy – putting it on a par with the standard test for high-risk HPV. But when the S5 test was used on HPV positive women, the figure rose to 96%.

“This methylation test has been used on clinical samples and then shown to help identify those women with HPV [who also] really have serious disease,” said Cuzick. “This is the first time we have suggested that the same can be done on a self sample.”

Dr Belinda Nedjai, another member of the team, said the findings suggest it might be possibly to use home samples both to spot those with HPV and identify those who are likely to have precancerous or cancerous cells and hence need to be referred for colposcopy investigations. That could mean an end to clinic-based cervical smears, although she said such an approach should first be used for women who do not attend screening appointments.

Nedjai added the S5 test could also be valuable in countries without a screening programme in place.