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New test could make it easier to predict women's risk of developing cervical cancer

Some 99% of cervical cancers are caused by HPV.

File photo
File photo
Image: Shutterstock/Komsan Loonprom

A NEW TEST that enhances the ability to predict the risk of developing cervical cancer in women who have human papillomavirus (HPV) has been developed.

Researchers based in France have developed a two-fold test that can detect and determine the type of HPV infection, as well as the likelihood of it progressing to cancer.

Most people will get a HPV infection in their lifetime and it usually clears up by itself. For women, ongoing HPV infections can cause abnormal changes in the lining of the cervix.

Some 99% of cervical cancers are caused by HPV. More than 200 HPVs associated with varying degrees of cancer risk complicate diagnosis and treatment.

The new test – which is different to the HPV test due to be rolled out in Ireland – may improve the ability to diagnose the riskiest forms of HPV infection, provide rapid results at low cost, and help avoid unnecessary diagnostic procedures.

The novel procedure, called HPV RNA-Seq, detects high-risk HPV infection and identifies patients with high-grade squamous intraepithelial lesions (HSIL), which is a precancerous stage of the cervix.

Cervical cancer screening allows detection and treatment of precancerous lesions before cancer develops. Currently, screening either focuses on testing for HPV or identifying abnormal cervical cells through cytology (the study of individual cells).

However, molecular diagnostic tests that detect the DNA or RNA of viruses are poor at identifying cancer or precancerous lesions.

Analysis of cervical cells via smear tests, even when combined with molecular detection of high-risk HPV, results in a significant number of unnecessary colposcopies, an invasive test by which the physician visually checks for cervical lesions.

In the study, HPV RNA-Seq was used to analyse samples from 55 patients, 28 with low-grade squamous intraepithelial lesions (LSIL) and 27 patients with precancerous HSIL.

The test was able to detect and determine the type of HPV infection among a panel of 16 high-risk HPVs, with results comparable to a widely used and officially approved HPV DNA molecular diagnostic kit. The test actually detected two more HPV-positive patients than the DNA test and also identified more patients with multiple HPV infections.

HPV vaccine rates in Ireland 

HPV vaccination rates in Ireland vary by county – from just 40% in Kerry to 74% in parts of Dublin. No areas have achieved the national target of 80%.

The vaccine, currently only available to girls, is due to be rolled out to boys from next month. Some 75% of HPV-linked cancers develop in women and 25% occur in men.

208232_web Papillomavirus particles Source: © Institut Pasteur/Odile Croissant

The CervicalCheck screening programme in Ireland offers smear tests to women aged between 25 and 60 every three years. Smear tests look for cell changes in the cervix, they do not test for cervical cancer.

There is a large backlog of tests and delays in women receiving their results, after a number of controversies emerged last year, including the fact that there should have been an earlier intervention in relation to more than 200 smear tests.

During the week, the HSE apologised after a rapid review identified over 4,000 cases where women who had smear tests weren’t told of their results through a combination of IT issues and human error.

In 873 of these cases, no letters about test results were issued to the women or their GPs. In the other 3,200 cases the results were issued to GPs but not to the women involved. The HSE stressed that the women affected in these cases were at “low clinical risk”.

High ability to detect HPV

The new test was found to have a sensitivity rate of 97.3% (ability to detect the presence of HPV) and negative predictive value of 93.8% (NPV, likelihood of not having HPV). 

“Effective cervical cancer screening requires high sensitivity and NPV for high-risk HPV infection, since women with a negative HPV test are usually tested again only after several years,” lead investigator Professor Marc Eloit, of the Biology of Infection Unit at  Institut Pasteur in Paris, said. 

Cytology (the study of cells) is used as a rapid method to treat patients with HPV, whereas histology (the study of whole human tissue) is considered the highest standard for cervical cancer diagnosis. The latter, however, is more invasive and requires more time to get results.

To determine if the new test has a place in cervical cancer treatment, the investigators compared it to cytology, with encouraging results. They found that the test’s ability to predict a woman’s likelihood of having HPV infection versus histology was always greater than that of cytology versus histology.

Eloit said this observation “constitutes a solid argument” in favour of a potential added medical value of the new test compared with cytology.

He added that the use of HPV RNA-Seq in certain patients could help eliminate unnecessary colposcopies (which are carried out if a smear test finds abnormal changes in the cells of the cervix). 

Eloit said, in the future, technology will likely allow many samples to be run simultaneously, lowering the cost to about €9-18 per test. The test may also be applicable for other HPV-associated cancers such as anal cancer and head and neck cancer.

The research, published by Elsevier, is outlined in a report in The Journal of Molecular Diagnostics.

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Órla Ryan

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