What cervical screening is appropriate for women who have been vaccinated against high risk HPV? A simulation study. Issue 4 (10th November 2017) - Landy, Rebecca
Abstract : Women vaccinated against HPV16/18 are approaching the age for cervical screening; however, an updated screening algorithm has not been agreed. We use a microsimulation model calibrated to real published data to determine the appropriate screening intensity for vaccinated women. Natural histories in the absence of vaccination were simulated for 300, 000 women using 10, 000 sets of transition probabilities. Vaccination with ( i ) 100% efficacy against HPV16/18, ( ii ) 15% cross‐protection, ( iii ) 22% cross‐protection, ( iv ) waning vaccine efficacy and ( v ) 100% efficacy against HPV16/18/31/33/45/52/58 was added, as were a range of screening scenarios appropriate to the UK. To benchmark cost‐benefits of screening for vaccinated women, we evaluated the proportion of cancers prevented per additional screen (incremental benefit) of current cytology and likely HPV screening scenarios in unvaccinated women. Slightly more cancers are prevented through vaccination with no screening (70.3%, 95% CR: 65.1–75.5) than realistic compliance to the current UK screening programme in the absence of vaccination (64.3%, 95% CR: 61.3–66.8). In unvaccinated women, when switching to HPV primary testing, there is no loss in effectiveness when doubling the screening interval. Benchmarking supports screening scenarios with incremental benefits of ≥2.0%, and rejects scenarios with incremental benefits ≤0.9%. In HPV16/18‐vaccinated women, the incremental benefit of offering a third lifetime screen was at most 3.3% (95% CR: 2.2–4.5), with an incremental benefit of 1.3% (−0.3–2.8) for a fourth screen. For HPV16/18/31/33/45/52/58‐vaccinated women, two lifetime screens are supported. It is important to know women's vaccination status; in these simulations, HPV16/18‐vaccinated women require three lifetime screens, HPV16/18/31/33/45/52/58‐vaccinated women require two lifetime screens, yet unvaccinated women require seven lifetime screens. Abstract : What's new? In England, the first cohorts of teenage girls to be vaccinated against human papillomavirus (HPV) will soon be entering the country's cervical cancer screening program. However, appropriate screening intervals for vaccinated women are yet to be established. Here, the necessary number of lifetime screens for HPV16/18‐vaccinated women and HPV16/18/31/33/45/52/58‐vaccinated women was determined using the proportion of cancers prevented per screen benchmarked against current screening practice. The findings suggest that three lifetime screens would be sufficient for cervical cancer prevention in HPV16/18‐vaccinated women, while just two lifetime screens would be effective for HPV16/18/31/33/45/52/58‐vaccinated women.