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Why HPV testing is an important development in screening women for cervical cancer

The introduction of HPV testing for cervical screening will be difficult, but it will be ultimately worth it says GP Dr Jane Woyka

This year sees the incorporation of HPV triage into our screening programme. HPV virus is found in almost 100% of cervical cancer cases and it is almost now universally accepted that HPV is a prerequisite for cervical cancer. The ARTISTIC and TOMBOLA Trials investigated the place of HPV testing in the programme and the Sentinel Sites Implementation Project explored the practical implications. We are set to introduce HPV triage into the national programme and commissioning will begin soon.

The easy incorporation of HPV testing has come about through the recent move to liquid-based cytology (rather than the old-fashioned smearing of a sample onto a slide). The sample obtained from the cervix is now transferred to a liquid medium which allows for further tests to be done including HPV.

Overall HPV testing has clear benefit, both for patients and providers. HPV triage provides another level of evaluation of possible disease which will reduce the need for repeat testing. In terms of patient acceptability this is a huge advantage as patients will be spared the anxiety of review. There is less likelihood of losing those patients who do not attend for reviews, but the disadvantage is that there may be an increased number of treatments that turn out to have been unnecessary.

HPV triage will be introduced initially in two ways. Firstly as HPV triage of low-grade abnormalities and secondly as ‘test of cure'. In 2008 of the total 250,000 abnormal cervical screening results, 200,000 were borderline or mild. Previously, patients with these results could have up to three six-monthly reviews before referral to colposcopy. With triage, patients with an HPV-positive result are referred immediately to colposcopy and those with a negative result returned to normal recall.

At the sentinel sites, about one third of low grade abnormalities were HPV negative. We may expect then around 140,000 referrals for colposcopy in the first year, followed then by a reduction when all the previous 'review' samples are triaged in the first round.

For the provider there will ultimately be a reduced number of screening tests required, but the initial increase in referrals for colposcopy might at first overwhelm the services.

‘Tests of cure' triage

Patients who have undergone colposcopic treatments (usually LETZ) for cervical disease will no longer undergo 10-year annual screening review. Instead, HPV testing will occur at their first follow up and those with HPV negativity returned to normal call and recall.

In 2008 there were 23,500 treatments, of which up to 2,300 cases might be returned for further treatment at the first review, (given treatment is at least 90% successful). There may be a small temporary increase in follow up colposcopy, but more than 20,000 patients will be returned to normal follow-up, and over a period of ten years reducing the number of ‘unnecessary' review screenings will result in a reduction of 200,000 tests.

Service providers are being advised to introduce one triage system at a time, as there are concerns that 100,000 extra colposcopy referrals in the first year would swamp the service.

Might the standards of colposcopy be compromised because lesions are missed and the referrals is too early? The sentinel sites piloting HPV triage over the last two years operated a hub and spoke format. When a cytology result is reported as low-grade, it must be identified, retrieved and posted to the hub for HPV assay, and the results sent out with cytology all within the 14 -day results target, a daily deadline which units throughout the country may have difficulty in achieving. However, accurate detection and treatment of disease will remain at a high level and possibly increase as HPV testing may be attractive to current non-attenders.

An HPV test may also be a much more appealing screening test for patients in the 25 to 35 age cohort for whom attendance rates are low. One might also hope that in countries where girls have received HPV vaccinations in their early teens they may be more aware of the value of HPV testing and cervical screening. The option of doing self-testing using kits has shown to increase the participation of non-attenders by over 50%. HPV testing may well have a role in countries with no cervical screening where cytology services are non-existent. There are also a large number of HPV testing systems, which vary in sensitivity and reliability, and there is stiff competition amongst the companies.

The most exciting development will be of course in 2015 when the first 18-year olds vaccinated with HPV are invited for screening. With an uptake of 80% vaccination against at least two strains of high-risk HPV the incidence of cervical abnormalities should be reduced by at least 60% and the lifetime need for screening considerably reduced.

This is the opinion of Dr Jane Woyka who is a GP in Harrow and a ACCS member

Dr Jane Woyka