Oncogenic HPV types 16 and/or 18

Women who have a positive oncogenic HPV test result indicating the presence of oncogenic HPV types 16 and/or 18, regardless of the presence of any other oncogenic types, should be managed according to the recommendations in this section.

These guidelines incorporate recommended HPV, cytology and histopathology terminology (see Chapter 3. Terminology).

Cross-sectional and longitudinal follow-up studies have shown that HPV type 16 is associated with a higher cross-sectional and future risk of developing CIN grade 2 or higher (CIN2+) and CIN grade 3 or higher (CIN3+) than other oncogenic HPV types.^[1] Worldwide, oncogenic HPV types 16/18 are detected in approximately 70% of cervical cancers.^[2] Preliminary results from a recent Australian consecutive case series found that HPV types 16 and 18 were detected in 52.3% and 19.4% of cervical cancers, respectively.^[3]

HPV testing without genotyping has a high sensitivity but lower specificity for the detection of CIN2+ compared to cytology,^[4] so referral of all HPV-positive women for colposcopic assessment (especially in unvaccinated populations) would result in a large number of unnecessary colposcopy procedures. However, partial genotyping to detect the highest risk oncogenic HPV types 16/18 can be used to stratify risk after primary HPV screening and thus improve the specificity of the HPV test.

MSAC undertook systematic reviews and modelling analyses to assess the efficacy and safety of the partial genotyping strategy in which women with a positive oncogenic HPV (16/18) test result are referred to colposcopy, and those with a positive oncogenic HPV (not 16/18) test result are triaged by LBC. MSAC compared this and other HPV testing strategies with the cytological screening strategy used in the pre-renewal NCSP.

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MSAC systematic reviews

The details and results of the systematic reviews are described in the MSAC review of evidence report.^[1] No studies were identified that provided adequate evidence of the effect of HPV partial genotyping screening strategies on cervical cancer incidence or cervical cancer mortality rates in either vaccinated or unvaccinated populations.

See the MSAC National Cervical Screening Program renewal: evidence review November 2013.

MSAC modelling

Given the limited evidence from systematic reviews, MSAC evaluated partial genotyping strategies in the Australian context using a comprehensive model to synthesise clinical trial evidence identified through systematic reviews and Australian data for screening participation, HPV vaccine uptake by age, and management practices.^[4]

The modelling approach, assumptions and options are described in the MSAC reports.^[4][5] The modelling for HPV primary screening with partial genotyping indicated an expected reduction in cancer incidence and mortality of over 20% (if women were screened until age 70 years).

See MSAC outcomes. Application No. 1276 – Renewal of the National Cervical Screening Program.

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Flowchart 6.3. Cervical screening pathway for primary oncogenic HPV screening (HPV tests on clinician-collected or self-collected samples): HPV16/18 detected

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When making the recommendation to refer women with a positive oncogenic HPV (16/18) test result directly for colposcopic assessment, MSAC took into account the benefits and harms and the health system implications of partial genotyping and immediate colposcopy in this group.

Updated modelling, taking into account the recommendations in these guidelines, has informed an assessment of the benefits and harms of partial genotyping. The updated modelling used the same platform as that used for the MSAC evaluation (POLICY1-Cervix),^[5] and took into account the Renewed NCSP screening recommendations and management as specified in these guidelines. The findings are summarised in Chapter 5. Benefits, harms and cost-effectiveness of cervical screening in the renewed National Cervical Screening Program (NCSP).

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Clinical practice

The referral of women with a positive oncogenic HPV (16/18) test result for colposcopy, regardless of the LBC prediction, is a major change to clinical practice and requires appropriate education and implementation.

Resourcing

When making this recommendation, MSAC took into account the resourcing issues for partial genotyping and the referral of women with a positive oncogenic HPV (16/18) test result for immediate colposcopy.

Updated modelling, taking into account these detailed Guideline recommendations, and taking into account the reduction in oncogenic HPV 16/18 infections due to vaccination in the population, has informed an assessment of the resourcing associated with partial genotyping strategies (see Chapter 5. Benefits, harms and cost-effectiveness of cervical screening in the renewed National Cervical Screening Program (NCSP)).

Barriers to implementation

A potential barrier is that GPs may not refer women who have a positive oncogenic HPV (16/18) test result to colposcopy, especially if the reflex LBC report is negative. However, the risk of this will be mitigated by the laboratory report to the GP clearly recommending referral and the NCSR follow-up protocols with reminder letters as needed.

A second potential barrier is that the woman may not fully understand the need for colposcopy, especially if the reflex LBC report is negative, and may not attend. NCSR reminder letters will play an important role in this situation.

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