HPV testing as triage and test of cure (TOC)
A number of sentinel sites began HPV testing as triage for women with mild or borderline test results in early 2007.
Improving Outcomes: A Strategy for Cancer (Jan 2011) announced the roll out of HPV testing across England as triage for women with borderline or low-grade cervical screening test results and as a test of cure (TOC) for women previously treated for cervical abnormalities.
Roll out to all areas began towards the end of March 2012.
Laboratories implemented a phased roll out for the implementation of HPV testing for triage and TOC over a 2 year period to 31 March 2014, and the policy became routine from 1 April 2014.
Prior to the introduction of HPV testing as triage women with borderline or low-grade cytology results were recalled for a repeat test in around 6 months and only referred if the abnormality persisted.
HPV testing as triage impact
The introduction of HPV testing as triage has been found to initially increase referrals to colposcopy (Moss et al, 2011)6.
At first, the introduction of HPV testing as triage increased the numbers of referrals to colposcopy as referrals can be speeded up where women test positive for HPV.
HPV testing as triage also increases the numbers of women who are returned to routine recall status and thereby decreases the numbers of women on early repeat recall due to abnormality.
Early repeat recall due to abnormality requires one or more further tests, typically around 6 months of the previous test, before the woman can be returned to routine recall.
An evaluation of HPV triage at six sentinel sites suggested that it would “…allow approximately a third of all borderline and mildly dyskaryotic women to be returned immediately to routine recall…” (Moss et al, 2011, p 8).
HPV primary screening
The NHS Cervical Screening Programme began an HPV primary screening pilot in May 2013 in 6 pathology laboratories (Bristol, Liverpool, London, Manchester, Norwich, and Sheffield).
The pilot aimed to: “establish whether using HPV testing as the primary screen for cervical disease results in better outcomes for women, while minimising over-treatment and anxiety, and whether it is practical to roll out nationally”7.
HPV primary screening differs from the usual process for examining cervical samples cytologically, instead the sample is first tested for HPV and where a sample tests positive for HPV a cytology screen is then performed. Therefore cytology acts as the triage.
Evidence suggests that testing for HPV first is more sensitive at detecting abnormalities. HPV primary screening may therefore be a better way of identifying women at risk of developing cervical cancer.
In HPV primary screening if the sample is found to be HPV negative, the woman is returned to routine recall and invited for screening again in 3 or 5 years’ time depending on her age.
If the sample is HPV positive, a slide is prepared from the same sample and is then examined by the cytologist for any abnormal cells.
Women who have an HPV positive result with a cytology negative result, will be recalled in 12 months for a further screen.
A negative HPV result will achieve a longer protection than the current cytology method of examining cervical samples.
In future women who test negative for HPV may not need to attend screening as frequently. The UK National Screening Committee (UK NSC) has evaluated evidence and has recommended that in HPV screening, intervals can be extended to 5 years for all age groups.
The implementation of 5 year extended screening intervals is being planned, however this will only be possible once there is full conversion to HPV primary screening.
HPV primary screening impact
Implementation of HPV primary screening across England has had an unintended impact on the cytology workforce and reduced cytology screening capacity.
This has led to an increase in the turnaround times of cervical screening samples since 2016-17. Further information on this issue can be found in Appendix J of the appendices document.
Colposcopy activity is expected to increase in the incident round of HPV primary screening but this is expected to be temporary with data showing that referral rates had roughly halved by the prevalent round.