Guidance

Cervical screening: pathway for acceptance of new human papillomavirus tests

Updated 20 February 2024

This document details the process for the acceptance of new human papillomavirus (HPV) tests for use within the UK cervical screening programmes. It will be reviewed and updated in line with future developments in HPV technology. It has been written collaboratively with representatives from the English, Scottish, Welsh and Irish cervical screening programmes, but content specifically relates to the NHS Cervical Screening Programme in England.

1. Governance

The Clinical Professional Group for Laboratories (Laboratory CPG) gives expert advice to NHS England on key operational aspects of the cervical screening programme. This includes making recommendations for the introduction of new liquid-based cytology (LBC), HPV and other technologies related to cervical screening.

The Laboratory Technology Group (LTG) is a subgroup of the Laboratory CPG, and manages the process for evaluating new LBC and HPV technologies on its behalf. The group is responsible for creating and reviewing the pathway for the acceptance of new tests.

2. Overview of the pathway

2.1 Phase 1: notification of interest

The commercial provider notifies the chair of the LTG of its interest in having a test and/or platform evaluated for use in the NHS Cervical Screening Programme (NHSCSP).

2.2 Phase 2a: assessment

The LTG makes an assessment of existing international data on the analytical and clinical performance of the assay.

2.3 Phase 2b: observation

A member of the LTG or their nominated delegate (from this point termed ‘LTG representative’) makes an observation of the platform in-situ (including pre-analytic or pre-processing platforms).

2.4 Phase 3: internal validation

There is an internal validation of the assay in the host laboratory subject to the successful completion of Phases 1, 2a and 2b.

All laboratories that provide high-risk human papillomavirus (hrHPV) testing for the NHSCSP are committed to ongoing quality monitoring of assay-performance implicit in ISO 15189. Laboratories must adhere to NHSCSP guidance on laboratory quality control and assurance for HPV testing. Laboratories report all acute issues that relate to performance of the NHS Cervical Screening Programme to the Screening Quality Assurance Service (SQAS).

3. Phases in the pathway

The following sections describe the phases in more detail.

3.1 Phase 1: notification of interest

Interested commercial providers must contact the chair of the LTG to confirm their intention to submit an application and the approximate timeframe for this. The application must include details of the main characteristics of the assay, and the supporting information as described in Appendix B.

3.2 Phase 2: assessment of existing data and observation of the platform

Phase 2a: a ‘dry’ assessment of existing data on the analytical, clinical and operational performance of the assay

Submitted data enables the LTG to assess the clinical performance of the new HPV test as a first-line primary screening test. Ideally, commercial providers should provide peer reviewed data on how the assay performs according to Meijer 2009 criteria. This should include data from laboratories in England and those relevant to the UK cervical screening programmes (CSPs).

The LTG requires commercial providers to submit reports on the performance of the assay as a triage of low grade abnormalities and as a test of cure of treatment (where available), with an emphasis on peer reviewed publications. If peer review data is not available then companies must provide sufficient unpublished data around assay performance.

The requirements for clinical data assessment are:

• that clinical performance of the new test must be compared to a clinically validated NHSCSP approved test
• 60 histologically confirmed CIN2+ to determine clinical sensitivity (relative sensitivity for the new assay should be at least 90%); details of the samples including a representative proportion of HPV+/cytology - CIN2+ samples of around 30% (n=18)
• 800 CIN2+ negative samples to determine clinical specificity (relative specificity for the new assay should be at least 98%) - include details of the samples, a component of which should be derived from an HPV positive or cytology negative group that is representative of primary screening populations
• demonstration of inter and intra laboratory reproducibility; for validation criteria to be satisfied, the 95% lower confidence bound of both agreements should be >87%, with a kappa value equal to or exceeding 0.5

At the time of writing, the Meijer 2009 criteria are under review and the timeline for update is unknown. We recognise that any update is likely to affect the nature of review and assessment during Phase 2.

Additionally, other (non-Meijer) requirements for test capabilities and performance may arise in ‘real-time’ due to the evolving nature of the programme. The LTG may ask a commercial provider to submit further data to address additional requirements and this may be in advance of a formal update of the acceptance pathway.

Data from manufacturers on operational performance should include:

• the number of laboratories where the particular platform is currently sited and processing specimens collected in ThinPrep™ and, or SurePath™ LBC
• turnaround time from primary vial to end result (this should incorporate pre-analytics) based on a 9am to 5pm, 5 day week
• workflow diagrams to summarise options for efficient testing
• the anticipated technical failure rate, based on failure of endogenous control or calibration or instrumentation issues; ideally these data should be drawn from a service laboratory

Phase 2b: observation of the platform* in-situ (including pre-analytic or pre-processing platforms)

*note that in the context of this document ‘platform’ means the particular combination of pre-analytical and analytical components.

Phase 2b supports the confirmation of operational performance in a laboratory setting. Commercial providers should contact the chair of the LTG for the contact details of a member of the LTG (or LTG representative) to carry out the site visit.

The commercial provider will facilitate and fund a site visit for observation of the platform ideally in an independent laboratory accredited for HPV testing to ISO15189, or equivalent standard outside the UK. NHSCSP laboratories are not a requirement, and a site visit may involve a non-UK laboratory.

The LTG representative will have first-hand experience of automated platforms to support HPV based screening. During the site visit, there must be an opportunity for the LTG representative to engage with users of the platform independent of the commercial provider.

The LTG representative prepares a short report of the site visit which is shared with the user prior to its dissemination to the wider LTG. The report includes a description of the laboratory visited and platform assessed, and a summary of strengths and weaknesses perceived by the staff at the laboratory site and by the LTG representative.

In the event that a new platform with the HPV test has never been placed into a laboratory setting, the host laboratory interested in the new test may elect to provide the validation in line with Phase 3 of this guidance. The commercial provider must fund the cost of kits, staff time and transportation for Phase 3.

On completion of Phase 3, an LTG representative carries out a site visit to observe the platform as for Phase 2b.

3.3 Phase 3: validation of the assay in the host laboratory

Subject to successful completion of Phases 1, 2a and 2b, a host laboratory (UK) providing primary HPV cervical screening carries out the internal validation prior to final approval.

We recognise that internal validations designed to demonstrate clinical performance are beyond the scope or resource of laboratories. Instead, validation includes the assessment of pre-annotated stored material in addition to quality materials (external and/or internal).

The commercial provider should support internal validation. We anticipate that manufacturers will supply the kits required to support validation at no cost.

Before live use:

• the commercial provider determines the success of installation using analytical checks and processes relevant to the platform and provide documentation to confirm this
• an analytical validation panel of 16 samples in triplicate (n=48) with known or anticipated results should be tested over 3 independent runs by 3 separate operators

Samples within the panel may include:

• standard positive and negative control material associated with the assay or platform
• residual material from HPV external quality assessment (EQA) schemes
• HPV containing cell line material, including that provided by the National Institute for Biological Standards and Control (NIBSC)
• other independently sourced HPV control material

An example of a validation panel is shown in Table 1 below.

Table 1: validation panel of 16 samples composed of independent or external control material

	1	2	3	4	5	6
A	CP Pos -1	REQA 03-1	REQA 01-2	REQA 09-2	REQA 07-3	Cell-16-2
B	CP Neg-1	REQA 04-1	REQA 02-2	REQA 10-2	REQA 08-3	Cell-18-2
C	CP Pos -2	REQA 05-1	REQA 03-2	REQA 01-3	REQA 09-3	Cell-45-2
D	CP Neg-2	REQA 06-1	REQA 04-2	REQA 02-3	REQA 10-3	Cell-Neg-2
E	CP Pos -3	REQA 07-1	REQA 05-2	REQA 03-3	Cell-16-1	Cell-16-3
F	CP Neg-3	REQA 08-1	REQA 06-2	REQA 04-3	Cell-18-1	Cell-18-3
G	REQA 01-1	REQA 09-1	REQA 07-2	REQA 05-3	Cell-45-1	Cell-45-3
H	REQA 02-1	REQA 10-01	REQA 08-2	REQA 06-3	Cell-Neg-1	Cell-Neg-3

CP = standard controls produced by commercial provider
REQA = residual material from external quality assurance schemes
Cell-16, 18, 45, Neg = cell line material associated with HPV 16, 18, 45 or no HPV

Acceptance criteria

A panel of 48 samples (including at least 25% positives) with a reference, clinically validated assay, and achieving at least 87% concordance between observed and expected results is a reasonable guide for acceptance.

Stress test

After demonstrating satisfactory performance with the validation panel, a ‘stress test’ resembling the manufacturers maximum sample throughput during a minimum 8-hour shift is performed and repeated over 5 days. This offers the laboratory ability to optimise workflow before going live in addition to analysing operational performance at scale.

The use of ‘real’ samples is necessary for the stress test to demonstrate any potential related issues such as: * platform mechanical errors * between sample contamination * number of technically invalid samples * platform downtime

The laboratory must document all related issues.

Suitable samples should be stored materials from a HPV primary screening laboratory ready for discard and must include positive or simulated positive samples between 10 to 20%.

The laboratory should stress test samples defined by the manufacturers’ recommendations for storage period and temperature wherever possible. Anonymise all samples prior to testing. If an NHS primary screening laboratory is required to send routine surplus LBC samples to another laboratory for stress testing, note that it may be necessary to pool material and decant into new and unlabelled LBC vials.

The manufacturer of the new test under evaluation is required to cover the costs of any reagents, staff time and transferring material between laboratories.

Validation report

The host laboratory submits a validation report to the Laboratory Technology Group. The report includes performance related to the validation panel and stress test, highlighting any significant problems or issues. Other elements which relate to the local validation report templates may also be included (these may vary slightly depending on the laboratory concerned).

In exceptional circumstances, where a commercial provider has not been able to place a test system within an NHS Primary HPV Screening laboratory, they can request phase 3 be performed in a UK laboratory not providing primary HPV testing to the UK Screening Programmes. The prospective laboratory must be independent of the commercial provider. It must be able to demonstrate a high level of skill and relevant expertise achieved through involvement in research and development in either surveillance of HPV infections or assessment and validation of new HPV test technologies.

4. Approval and sign off

After completion of Phases 2a, 2b and 3, the LTG reports to the Laboratory CPG. The Laboratory CPG considers the recommendations from the LTG and those which are ratified are submitted to the SMG for formal approval. SMG approval results in an update to the list of acceptable tests.

5. Internal validation

After formal approval, any subsequent laboratory choosing to use the new approved platform must carry out an internal validation as described in Phase 3. Note that the stress test element is not obligatory for every laboratory.

The laboratory must send the validation report to the chair of the LTG for completeness of record. The LTG secretariat retains a soft copy of all validation reports that relate to laboratories which support the NHSCSP.

Note that yearly verification is required by the United Kingdom Accreditation Service (UKAS). This is the responsibility of laboratories and beyond the scope of this guidance.

6. Modification of CE marked tests

If a commercial provider plans to modify the accepted platform (including for pre-analytical processes), they must provide details of the modification to the chair of the LTG prior to its implementation. The chair of the LTG then communicates this information to the wider group for consideration.

The LTG determines if further evaluation work is required and the extent or nature of additional assessment (which reflect the extent of the modification) prior to the modification being accepted into the NHSCSP. For example, if the amplification chemistry of the assay has changed then it is likely phases 1 to 3 are required. For more minor modifications, repetition of phase 3 may suffice.

7. Verification of a new pre-analytic system

The process for verifying a new automated pre-analytic system prior to acceptance within the NHS CSP is described below. This process also fulfils the ISO 15189 standard for verifying new instrumentation prior to implementation within the laboratory.

The protocol aims to verify the pre-analytics for aliquoting Hologic Preservcyt samples using end-to-end HPV testing. This is achieved by:

• checks for reproducibility and reliable detection
• a sample contamination check
• a stress test depending on manufacturers run throughput (rigour of technology)
• identifying the benefits of the new system compared to previous validated systems

Protocol:

Prepare a known panel of samples as follows:

1. 50 positives using pooled, residual, anonymised cervical samples or HPV containing cell line material associated with previous and consistent positivity (positive results on at least three replicates) on a validated platform. To mimic patient samples, prepare using Preservcyt solution and aliquot in 20ml volumes into empty Hologic Preservcyt vials.

2. 40 HPV negative cell lines for a negative control prepared in Preservcyt and aliquot in 20ml volumes into empty Hologic Preservcyt vials. Using negative pooled, residual, anonymised cervical samples are not ideal in this scenario as it may contain HPV material not previously detected.

3. 10 Preservcyt only vials with the original 20ml Preservcyt solution.

Place the vials in an alternating positive followed by negative or Preservcyt only ‘checkerboard’ sequence, introduce the samples onto the new pre-analytic system and test with the compatible HPV assay. There should be sufficient material to run the samples through the system at least 5 times over the course of a week. From the expected results and repeat results determine observed versus expected sensitivity and observed versus expected reproducibility. 

In addition to sensitivity and reproducibility, potential HPV contamination caused by the instrument can be determined by the HPV negative controls and Preservcyt only samples for HPV and cellular contamination respectively.  By using a checkboard sequence on the system any negatives that test positive or Preservcyt only samples that detect HPV and, or beta globin may be considered sample contamination caused by the instrument.

Running the pre-analytics over 5 days will allow the users to identify any issues, for example insufficient aliquoting, drips from a sample or crashed run and so on. 

Acceptance criteria

All acceptance criteria must be fulfilled:

• across all 5 runs >95% observed results should return the expected results at the level of qualitative HPV presence or absence
• across all 5 runs >90% reproducibility of positive samples
• across all 5 runs contamination should be observed in no more than 0.5% of samples for the HPV negative samples (to check for HPV contamination) and Preservcyt only samples (to check for HPV and cellular contamination)

Report

The report must outline the benefits of using a new pre-analytic system. Both the manufacturer and the laboratory testing the new system should identify the benefits compared to the current system(s) approved for the same HPV test. 

Any change from the protocol (due to the specifics of future instrumentation) will be adjudicated on a case-by-case basis.

8. List of accepted HPV tests

The list of accepted HPV tests is available on GOV.UK.

9. Removal of tests from the list of accepted HPV tests

Tests are removed from the list if they are no longer marketed in the UK or no longer meet the quality and performance requirements of the screening programme. In the latter scenario, this would most likely occur due to a planned major change to the programme or screening pathway recommended by the UK National Screening Committee (UK NSC). In this case, laboratories would have sufficient lead in times to make alternative arrangements.

Recommendations from the LTG to remove a test are submitted to the Laboratory CPG for ratification in the first instance. The LTG chair notifies test manufacturers or commercial providers of the decision.

10. General enquiries

Commercial providers can contact the chair of the LTG by email at PHE.screeninghelpdesk@nhs.net. The subject line should state: FAO Chair – Laboratory Technology Group (cervical screening programme).

11. Application process for commercial providers

Information on the application process for commercial providers is in Appendix A.