Cervical Cancer Screening in Partly HPV Vaccinated Cohorts - A Cost-Effectiveness Analysis

Cervical screening among Chinese females in the era of HPV vaccination: a population-based survey on screening uptake and regular screening following an 18-year organized screening program

OBJECTIVE

China has a substantial disease burden of cervical cancer. To further understand preventive measures for reducing cervical cancer in China, this study aimed to correlate screening attendance and regular screening with human papillomavirus (HPV) vaccination among Chinese females.

METHODS

This prospective questionnaire-based survey recruited Chinese females aged 25 or above in Hong Kong by random digit dialing telephone interviews in 2022. The survey studied women's practice of cervical screening and adherence to regular screening. Variables including HPV vaccination status and attendance of physical check-ups were involved in the questionnaire. Screening uptake and screening adherence were the main outcomes, which were measured as the proportion of women who reported having attended a cervical screening and screened regularly, respectively.

RESULTS

Out of 906 valid respondents, the reported cervical screening uptake was over 70% among females aged 30 or above and particularly over 80% among women aged 35-59; however, the uptake was only 46% among those aged 25-29. Adherence to regular screening was 50%-60% across ages 25-59 years and dropped to approximately 40% for women older than 60 years. Both screening uptake and adherence were associated with HPV vaccination, with adjusted odds ratios of 2.37 and 2.23, respectively. A large proportion of regularly screened women may be overscreened for screening more frequently than recommended.

CONCLUSION

Responded Chinese females showed good cervical screening uptake but were moderately adherent to regular screening. Policymakers should emphasize the importance of regular screening and the recommended screening frequency by HPV vaccination status for better healthcare resource use.

Maximizing the cost-effectiveness of cervical screening in the context of routine HPV vaccination by optimizing screening strategies with respect to vaccine uptake: a modeling analysis

BACKGROUND

Regarding primary and secondary cervical cancer prevention, the World Health Organization proposed the cervical cancer elimination strategy that requires countries to achieve 90% uptake of human papillomavirus (HPV) vaccines and 70% screening uptake. The optimal cervical screening strategy is likely different for unvaccinated and vaccinated cohorts upon national HPV immunization. However, health authorities typically only provide a one-size-fits-all recommendation for the general population. We aimed to evaluate the cost-effectiveness for determining the optimal screening strategies for vaccinated and unvaccinated cohorts.

METHODS

We considered the women population in Hong Kong which has a unique HPV infection and cervical cancer epidemiology compared to other regions in China and Asia. We used mathematical models which comprise a deterministic age-structured compartmental dynamic component and a stochastic individual-based cohort component to evaluate the cost-effectiveness of screening strategies for cervical screening. Following the recommendations in local guidelines in Hong Kong, we considered strategies that involved cytology, HPV testing, or co-testing as primary cervical screening. We also explored the impacts of adopting alternative de-intensified strategies for vaccinated cohorts. The 3-year cytology screening was used as the base comparator while no screening was also considered for vaccinated cohorts. Women's lifetime life years, quality-adjusted life years, and costs of screening and treatment were estimated from the societal perspective based on the year 2022 and were discounted by 3% annually. Incremental cost-effectiveness ratios (ICERs) were compared to a willingness to pay (WTP) threshold of one gross domestic product per capita (US $47,792). Probabilistic and one-way sensitivity analyses were conducted.

RESULTS

Among unvaccinated cohorts, the strategy that adds reflex HPV to triage mild cytology abnormality generated more life years saved than cytology-only screening and could be a cost-effective alternative. Among vaccinated cohorts, when vaccine uptake was 85% (based on the uptake in 2022), all guideline-based strategies (including the cytology-only screening) had ICERs above the WTP threshold when compared with no screening if the vaccine-induced protection duration was 20 years or longer. Under the same conditions, HPV testing with genotyping triage had ICERs (compared with no screening) below the WTP threshold if the routine screening interval was lengthened to 10 and 15 years or screening was initiated at ages 30 and 35 years.

CONCLUSIONS

HPV testing is a cost-effective alternative to cytology for vaccinated cohorts, and the associated optimal screening frequency depends on vaccine uptake. Health authorities should optimize screening recommendations by accounting for population vaccine uptake.

Rapid elimination of cervical cancer while maintaining the harms and benefits ratio of cervical cancer screening: a modelling study

BACKGROUND

Human papillomavirus (HPV) vaccination and intensifying screening expedite cervical cancer (CC) elimination, yet also deteriorate the balance between harms and benefits of screening. We aimed to find screening strategies that eliminate CC rapidly but maintain an acceptable harms-benefits ratio of screening.

METHODS

Two microsimulation models (STDSIM and MISCAN) were applied to simulate HPV transmission and CC screening for the Dutch female population between 2022 and 2100. We estimated the CC elimination year and harms-benefits ratios of screening for 228 unique scenarios varying in vaccination (coverage and vaccine type) and screening (coverage and number of lifetime invitations in vaccinated cohorts). The acceptable harms-benefits ratio was defined as the number of women needed to refer (NNR) to prevent one CC death under the current programme for unvaccinated cohorts (82.17).

RESULTS

Under current vaccination conditions (bivalent vaccine, 55% coverage in girls, 27.5% coverage in boys), maintaining current screening conditions is projected to eliminate CC by 2042, but increases the present NNR with 41%. Reducing the number of lifetime screens from presently five to three and increasing screening coverage (61% to 70%) would prevent an increase in harms and only delay elimination by 1 year. Scaling vaccination coverage to 90% in boys and girls with the nonavalent vaccine is estimated to eliminate CC by 2040 under current screening conditions, but exceeds the acceptable NNR with 23%. Here, changing from five to two lifetime screens would keep the NNR acceptable without delaying CC elimination.

CONCLUSIONS

De-intensifying CC screening in vaccinated cohorts leads to little or no delay in CC elimination while it substantially reduces the harms of screening. Therefore, de-intensifying CC screening in vaccinated cohorts should be considered to ensure acceptable harms-benefits ratios on the road to CC elimination.

COVID-19 disruption to cervical cancer screening in England

INTRODUCTION

In England, routine invitations for cervical screening were reduced between April 2020 and June 2020 due to the COVID-19 pandemic. We quantify the impact of COVID-19 disruptions on attendance and excess diagnoses of cervical cancer (CC).

METHODS

Using Public Health England CC screening data on laboratory samples received in 2018 as a baseline we quantify the reduction in screening attendances due to the COVID-19 pandemic between April 2020 and March 2021 for women aged 25-64. We model the impact on excess CC diagnoses assuming once invitations resume 87.5% of women attend within 12 months and 12.5% delay screening for 3 or 5 years (depending on age).

RESULTS

The number of samples received at laboratories was 91% lower than expected during April, 85% during May and 43% during June 2020 compared to the same period in 2018. Although on average laboratories received 12.6% more samples between August 2020 and April 2021 than over the same months in 2018, by April 2021 there was a short fall of 200,949 samples (6.4% fewer than in 2018). An excess of 41 CC (4.0 per 100,000 women with a maximum screening delay of 12 months) are predicted to occur among the estimated 1,024,794 women attending this screening round with a delay. An excess of 60 CC (41.0 per 100,000 women) are predicted to occur among the estimated 146,391 women who do not attend this screening round.

CONCLUSION

Prompt restoration of cervical screening services limited the impact on excess CC diagnoses. However, in 2020 a 6.4% shortfall of screening samples was observed. Every effort should be made to reassure these women that services are open and safe to attend.

Shift in harms and benefits of cervical cancer screening in the era of HPV screening and vaccination: a modelling study

Objective

To calculate the changes in harms and benefits of cervical cancer screening over the first three screening rounds of the Dutch high‐risk human papillomavirus (hrHPV) screening programme.

Design

Microsimulation study.

Setting

Dutch hrHPV screening programme; women are invited for screening every 5 or 10 years (depending on age and screening history) from age 30 to 65.

Population

Partly vaccinated population of 100 million Dutch women.

Methods

Microsimulation model MISCAN was used to estimate screening effects. Sensitivity analyses were performed on test characteristics and attendance.

Main outcome measures

Harms (screening tests, unnecessary referrals, treatment‐related health problems), benefits (CIN2⁺ diagnoses) and programme efficiency (number needed to screen [NNS]) over the first (period 2017–2021), second (period 2022–2026) and third (period 2027–2031) rounds of hrHPV‐based screening.

Results

The number of screening tests and CIN2⁺ diagnoses decreased from the first to the second round (−25.8% and −23.6%, respectively). In the third screening round, these numbers decreased further, albeit only slightly (−2.7% and −5.3%, respectively). NNS to detect a CIN2⁺ remained constant over the rounds; however, it increased in younger age groups while decreasing in older age groups.

Conclusion

Both harms and benefits of hrHPV screening decreased over the first screening rounds. For younger women, the efficiency would decrease, whereas longer screening intervals would lead to increased efficiency in older women. Programme efficiency overall remained stable, showing the importance of longer intervals for low‐risk women.

Tweetable abstract:

Cervical cancer screening: both harms and benefits of hrHPV screening will decrease in the future.

Cervical cancer screening: both harms and benefits of hrHPV screening will decrease in the future.

The Differential Risk of Cervical Cancer in HPV-Vaccinated and -Unvaccinated Women: A Mathematical Modeling Study

BACKGROUND

With increased uptake of vaccination against human papillomavirus (HPV), protection against cervical cancer will also increase for unvaccinated women, due to herd immunity. Still, the differential risk between vaccinated and unvaccinated women might warrant a vaccination-status-screening approach. To understand the potential value of stratified screening protocols, we estimated the risk differentials in HPV and cervical cancer between vaccinated and unvaccinated women.

METHODS

We used STDSIM, an individual-based model of HPV transmission and control, to estimate the HPV prevalence reduction over time, after introduction of HPV vaccination. We simulated scenarios of bivalent or nonavalent vaccination in females-only or females and males, at 20% coverage increments. We estimated relative HPV-type-specific prevalence reduction compared with a no-vaccination counterfactual and then estimated the age-specific cervical cancer risk by vaccination status.

RESULTS

The relative cervical cancer risk for unvaccinated compared with vaccinated women ranged from 1.7 (bivalent vaccine for females and males; 80% coverage) to 10.8 (nonavalent vaccine for females-only; 20% coverage). Under 60% vaccination coverage, which is a representative coverage for several western countries, including the United States, the relative risk (RR) varies between 2.2 (bivalent vaccine for females and males) and 9.2 (nonavalent vaccine for females).

CONCLUSIONS

We found large cervical cancer risk differences between vaccinated and unvaccinated women. In general, our model shows that the RR is higher in lower vaccine coverages, using the nonavalent vaccine, and when vaccinating females only.

IMPACT

To avoid a disbalance in harms and benefits between vaccinated and unvaccinated women, vaccination-based screening needs serious consideration.

Recovery strategies following COVID-19 disruption to cervical cancer screening and their impact on excess diagnoses

BACKGROUND

The COVID-19 pandemic has disrupted cervical cancer screening services. Assuming increases to screening capacity are unrealistic, we propose two recovery strategies: one extends the screening interval by 6 months for all and the other extends the interval by 36/60 months, but only for women who have already missed being screened.

METHODS

Using routine statistics from England we estimate the number of women affected by delays to screening. We used published research to estimate the proportion of screening age women with high-grade cervical intraepithelial neoplasia and progression rates to cancer. Under two recovery scenarios, we estimate the impact of COVID-19 on cervical cancer over one screening cycle (3 years at ages 25-49 and 5 years at ages 50-64 years). The duration of disruption in both scenarios is 6 months. In the first scenario, 10.7 million women have their screening interval extended by 6 months. In the second, 1.5 million women (those due to be screened during the disruption) miss one screening cycle, but most women have no delay.

RESULTS

Both scenarios result in similar numbers of excess cervical cancers: 630 vs. 632 (both 4.3 per 100,000 women in the population). However, the scenario in which some women miss one screening cycle creates inequalities-they would have much higher rates of excess cancer: 41.5 per 100,000 delayed for screened women compared to those with a 6-month delay (5.9 per 100,000).

CONCLUSION

To ensure equity for those affected by COVID-19 related screening delays additional screening capacity will need to be paired with prioritising the screening of overdue women.

Cervical screening in high-income countries: the need for quality assurance, adjunct biomarkers and rational adaptation to HPV vaccination

We here discuss human papillomavirus (HPV)-based screening avenues to achieve elimination of cervical cancer as a public health problem in high-income country (HIC) settings, covering both the most recent data on the performance of HPV testing, as well as the currently most robust triage methods that are known. We also provide an outlook to several other promising, yet not fully established, options for triage that have been proposed, including methylation, dual staining, machine learning, and artificial intelligence. Finally, we discuss the key issue of how to adapt screening in the presence of programmatic HPV vaccination, and how this combination can best be leveraged for comprehensive cancer control. We conclude that, for the HIC setting, evidence-based and effective cervical screening methods are readily available, but whichever method or platform is chosen, we would propose that recurring audits of performance and population attendance remain common denominators for maintaining successful disease prevention.

The optimal HPV-screening protocol in Eastern-Europe: The example of Slovenia

OBJECTIVE

Eastern European countries are contemplating to introduce the high-risk Human Papillomavirus (HPV)-test as the primary screening test for their cervical cancer screening programme, but its optimal protocol is yet unknown. The aim of this study was to compare the costs, effects and cost-effectiveness of different primary HPV-screening protocols in Eastern Europe, using Slovenia as an example and with respect of local preferences for screening.

METHODS

We evaluated 968 HPV-screening protocols, which varied by screening ages, triage tests (i.e. cytology, repeat HPV and/or genotyping) and strategy for women under 35 years old, using the microsimulation model MISCAN-Cervix.

RESULTS

Within the subset of strategies that would be acceptable for Slovenian women, the optimal HPV-screening protocol is to start with two cytology tests at age 25 and 28 and switch to 5-yearly HPV screening from age 30 to 65. When also other protocols were considered, the optimal screening strategy would be 5-yearly HPV screening from age 30 to 65 only, improving the cost-effectiveness with 5%. Adding genotyping in the triage algorithm consistently improved cost-effectiveness. Sensitivity analyses showed the robustness of the results for other situations in Eastern Europe.

CONCLUSIONS

Despite differences in cervical cancer epidemiology between Eastern and Western European regions where HPV screening was evaluated, the optimal screening protocol was found to be very similar. Furthermore, strategies that were considered socially acceptable to the population were found to be almost as cost-effective as less acceptable strategies and can therefore be considered a viable alternative to prevent opportunistic screening.

Cervical cancer screening for individuals at average risk: 2020 guideline update from the American Cancer Society

The American Cancer Society (ACS) recommends that individuals with a cervix initiate cervical cancer screening at age 25 years and undergo primary human papillomavirus (HPV) testing every 5 years through age 65 years (preferred); if primary HPV testing is not available, then individuals aged 25 to 65 years should be screened with cotesting (HPV testing in combination with cytology) every 5 years or cytology alone every 3 years (acceptable) (strong recommendation). The ACS recommends that individuals aged >65 years who have no history of cervical intraepithelial neoplasia grade 2 or more severe disease within the past 25 years, and who have documented adequate negative prior screening in the prior 10 years, discontinue all cervical cancer screening (qualified recommendation). These new screening recommendations differ in 4 important respects compared with the 2012 recommendations: 1) The preferred screening strategy is primary HPV testing every 5 years, with cotesting and cytology alone acceptable where access to US Food and Drug Administration-approved primary HPV testing is not yet available; 2) the recommended age to start screening is 25 years rather than 21 years; 3) primary HPV testing, as well as cotesting or cytology alone when primary testing is not available, is recommended starting at age 25 years rather than age 30 years; and 4) the guideline is transitional, ie, options for screening with cotesting or cytology alone are provided but should be phased out once full access to primary HPV testing for cervical cancer screening is available without barriers. Evidence related to other relevant issues was reviewed, and no changes were made to recommendations for screening intervals, age or criteria for screening cessation, screening based on vaccination status, or screening after hysterectomy. Follow-up for individuals who screen positive for HPV and/or cytology should be in accordance with the 2019 American Society for Colposcopy and Cervical Pathology risk-based management consensus guidelines for abnormal cervical cancer screening tests and cancer precursors.

Cost-effectiveness of HPV-based cervical screening based on first year results in the Netherlands: a modelling study

Objective

We aim to compare the cost‐effectiveness of the old cytology programme with the new high‐risk human papillomavirus (hrHPV) screening programme, using performance indicators from the new Dutch hrHPV screening programme.

Design

Model‐based cost‐effectiveness analysis.

Setting

The Netherlands.

Population

Dutch 30‐year‐old unvaccinated females followed up lifelong.

Methods

We updated the microsimulation screening analysis (MISCAN) model using the most recent epidemiological and screening data from the Netherlands. We simulated both screening programmes, using the screening behaviour and costs observed in each programme. Sensitivity analyses were performed on screening behaviour, utility losses and discount rates.

Main outcome measures

Cervical cancer incidence and mortality rates, number of screening tests and repeat tests, colposcopy referrals by lesion grade, costs from a societal perspective, quality‐adjusted life years (QALYs) gained and cost‐effectiveness.

Results

The new Dutch cervical cancer screening programme decreased the cervical cancer mortality by 4% and the incidence by 1% compared with the old programme. Colposcopy referrals of women without cervical intra‐epithelial neoplasia grade 2 or worse, increased by 172%, but 13% more QALYs were still achieved. Total costs were reduced by 21%, mainly due to fewer screening tests. Per QALY gained, the hrHPV programme cost 46% less (€12,225) than the cytology programme (€22,678), and hrHPV‐based screening remained more cost‐effective in all sensitivity analyses.

Conclusions

The hrHPV‐based screening programme was found to be more effective and cost‐effective than the cytology programme. Alternatives for the current triage strategy should be considered to lower the number of unnecessary referrals.

Tweetable abstract

First results after implementation confirm that HPV screening is more cost‐effective than cytology screening.

First results after implementation confirm that HPV screening is more cost‐effective than cytology screening.

Introduction of primary screening using high-risk HPV DNA detection in the Dutch cervical cancer screening programme: a population-based cohort study

BACKGROUND

In January 2017, the Dutch cervical cancer screening programme transitioned from cytomorphological to primary high-risk HPV (hrHPV) DNA screening, including the introduction of self-sampling, for women aged between 30 and 60 years. The Netherlands was the first country to switch to hrHPV screening at the national level. We investigated the health impact of this transition by comparing performance indicators from the new hrHPV-based programme with the previous cytology-based programme.

METHODS

We obtained data from the Dutch nationwide network and registry of histo- and cytopathology (PALGA) for 454,573 women eligible for screening in 2017 who participated in the hrHPV-based programme between 1 January 2017 and 30 June 2018 (maximum follow-up of almost 21 months) and for 483,146 women eligible for screening in 2015 who participated in the cytology-based programme between 1 January 2015 and 31 March 2016 (maximum follow-up of 40 months). We compared indicators of participation (participation rate), referral (screen positivity; referral rate) and detection (cervical intraepithelial neoplasia (CIN) detection; number of referrals per detected CIN lesion).

RESULTS

Participation in the hrHPV-based programme was significantly lower than that in the cytology-based programme (61% vs 64%). Screen positivity and direct referral rates were significantly higher in the hrHPV-based programme (positivity rate: 5% vs 9%; referral rate: 1% vs 3%). CIN2+ detection increased from 11 to 14 per 1000 women screened. Overall, approximately 2.2 times more clinical irrelevant findings (i.e. ≤CIN1) were found in the hrHPV-based programme, compared with approximately 1·3 times more clinically relevant findings (i.e. CIN2+); this difference was mostly due to a national policy change recommending colposcopy, rather than observation, of hrHPV-positive, ASC-US/LSIL results in the hrHPV-based programme.

CONCLUSIONS

This is the first time that comprehensive results of nationwide implementation of hrHPV-based screening have been reported using high-quality data with a long follow-up. We have shown that both benefits and potential harms are higher in one screening round of a well-implemented hrHPV-based screening programme than in an established cytology-based programme. Lower participation in the new hrHPV programme may be due to factors such as invitation policy changes and the phased roll-out of the new programme. Our findings add further to evidence from trials and modelling studies on the effectiveness of hrHPV-based screening.

HPV-FRAME: A consensus statement and quality framework for modelled evaluations of HPV-related cancer control

Intense research activity in HPV modelling over this decade has prompted the development of additional guidelines to those for general modelling. A specific framework is required to address different policy questions and unique complexities of HPV modelling. HPV-FRAME is an initiative to develop a consensus statement and quality-based framework for epidemiologic and economic HPV models. Its development involved an established process. Reporting standards have been structured according to seven domains reflecting distinct policy questions in HPV and cancer prevention and categorised by relevance to a population or evaluation. Population-relevant domains are: 1) HPV vaccination in pre-adolescent and young adolescent individuals; 2) HPV vaccination in older individuals; 3) targeted vaccination in men who have sex with men; 4) considerations for individuals living with HIV and 5) considerations for low- and middle-income countries. Additional considerations applicable to specific evaluations are: 6) cervical screening or integrated cervical screening and HPV vaccination approaches and 7) alternative vaccine types and alternative dosing schedules. HPV-FRAME aims to promote the development of models in accordance with an explicit framework, to better enable target audiences to understand a model's strength and weaknesses in relation to a specific policy question and ultimately improve the model's contribution to informed decision-making.

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General modelling guidelines are insufficient for reporting HPV models.

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HPV-FRAME is an initiative to develop a quality-based framework for HPV models.

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The framework has seven domains consisting of distinct reporting standards.

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HPV-FRAME aims to promote transparency and improve the quality in reporting.

[New strategies for the prevention and control of cervical cancer in Chile.]

OBJECTIVE

To discuss cervical cancer (CC), Human PapillomaVirus (HPV),CC control program and propose alternatives for Chile.

MATERIALS AND METHODS

We analyzed the national program of CC 1966-2015 and the clinical CC guideline 2015-2020;HPV prevalence in women and in cases of CC; HPV infection and serology; the self-vaginal sample; the accuracy and cost-effectiveness of screening with HPV versus Papanicolaou,and triage options among HPV-AR positives.

RESULTS

600 women die of CC each year in Chile, mainly from low resources. Papanicolaou coverage is <70%; Papanicolaou sensitivity is much lowerthan HPV test.Change from Papanicolaou to HPV test is cost-effective. Since 2015, girls under 13 have been vaccinated against HPV.

CONCLUSIONS

.There are the technical and economic conditions for a substantial improvement of CC in Chile: replacement of the Papanicolaou by HPV; screening every five years, with the option of self-sampling, and triage based on HPV 16/18 or Papanicolaou typing.

Cervical Cancer Screening Programs in Europe: The Transition Towards HPV Vaccination and Population-Based HPV Testing

Cervical cancer is the fourth most frequently occurring cancer in women around the world and can affect them during their reproductive years. Since the development of the Papanicolaou (Pap) test, screening has been essential in identifying cervical cancer at a treatable stage. With the identification of the human papillomavirus (HPV) as the causative agent of essentially all cervical cancer cases, HPV molecular screening tests and HPV vaccines for primary prevention against the virus have been developed. Accordingly, comparative studies were designed to assess the performance of cervical cancer screening methods in order to devise the best screening strategy possible. This review critically assesses the current cervical cancer screening methods as well as the implementation of HPV vaccination in Europe. The most recent European Guidelines and recommendations for organized population-based programs with HPV testing as the primary screening method are also presented. Lastly, the current landscape of cervical cancer screening programs is assessed for both European Union member states and some associated countries, in regard to the transition towards population-based screening programs with primary HPV testing.

The health impact of human papillomavirus vaccination in the situation of primary human papillomavirus screening: A mathematical modeling study

BACKGROUND

Human papillomavirus (HPV) vaccination and the implementation of primary HPV screening in the Netherlands will lead to a lower cervical disease burden. For evaluation and further improvement of prevention, it is important to estimate the magnitude and timing of health benefits of current and alternative vaccination strategies such as vaccination of boys or adults.

METHODS AND FINDINGS

We evaluated the impact of the current girls-only vaccination program and alternative strategies on cervical disease burden among the first four vaccinated five-year birth cohorts, given the context of primary HPV screening. We integrated the existing microsimulation models STDSIM (HPV transmission model) and MISCAN-Cervix (cervical cancer screening model). Alternative vaccination strategies include: improved vaccination uptake, including routine boys vaccination, and offering adult vaccination at sexual health clinics. Our models show that the current vaccination program is estimated to reduce cervical cancers and cancer deaths by about 35% compared to primary HPV screening in the absence of vaccination. The number needed to vaccinate (NNV) to gain 1 life year is 45. The most efficient alternative vaccination strategies are: 1) improving coverage of girls to 80% (NNV = 42); and 2) routine vaccination for girls and boys at 80% coverage (incremental NNV = 155), with cervical cancer mortality reductions estimated at 50% and 60% respectively.

CONCLUSIONS

While the current program already substantially reduces cervical cancer incidence and mortality, prevention can be further improved by increasing vaccination uptake and extending vaccination to boys. As not all cervical cancer deaths will be prevented, screening participation should still be encouraged.

Human papillomavirus vaccination and the role of herd effects in future cancer control planning: a review

INTRODUCTION

Vaccine herd effects are the indirect protection that vaccinated persons provide to those who remain susceptible to infection, due to the reduced transmission of infections. Herd effects have been an important part of the discourse on how to best implement human papillomavirus (HPV) vaccines and prevent HPV-related diseases.

AREAS COVERED

In this paper, we review the theory of HPV vaccine herd effects derived from mathematical models, give an account of observed HPV vaccine herd effects worldwide, and examine the implications of vaccine herd effects for future cervical cancer screening efforts.

EXPERT COMMENTARY

HPV vaccine herd effects improve the cost-effectiveness of vaccinating preadolescent girls, but contribute to making gender-neutral vaccination less economically efficient. Vaccination coverage and sexual mixing patterns by age are strong determinants of herd effects. Many countries worldwide are starting to observe reductions in HPV-related outcomes likely attributable to herd effects, most notably declining anogenital warts in young men, and declining HPV-16/18 infection prevalence in young unvaccinated women. Policy makers making recommendations for cervical cancer screening will have to consider HPV vaccination coverage and herd effects, as these will affect the positive predictive value of screening and the risk of cervical cancer in unvaccinated women.

Implementation considerations using HPV self-collection to reach women under-screened for cervical cancer in high-income settings

The success of cytology (Pap screening) programs is undeniable and has drastically reduced cervical cancer rates in high-income settings where it has been implemented [...]

What cervical screening is appropriate for women who have been vaccinated against high risk HPV? A simulation study

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.

Adapting cervical cancer screening for women vaccinated against human papillomavirus infections: The value of stratifying guidelines

BACKGROUND

Several countries have implemented vaccination against human papillomavirus (HPV) for adolescent girls and must decide whether and how to adapt cervical cancer (CC) screening for these low-risk women. We aimed to identify the optimal screening strategies for women vaccinated against HPV infections and quantify the amount that could be spent to identify vaccination status among women and stratify CC screening guidelines accordingly.

METHODS

We used a mathematical model reflecting HPV-induced CC in Norway to project the long-term health benefits, resources and costs associated with 74 candidate-screening strategies that varied by screening test, start age and frequency. Strategies were considered separately for women vaccinated with the bivalent/quadrivalent (2/4vHPV) and nonavalent (9vHPV) vaccines. We used a cost-effectiveness framework (i.e. incremental cost-effectiveness ratios and net monetary benefit) and a commonly-cited Norwegian willingness-to-pay threshold of €75,000 per quality-adjusted life-year gained.

RESULTS

The most cost-effective screening strategy for 9vHPV- and 2/4vHPV-vaccinated women involved HPV testing once and twice per lifetime, respectively. The value of stratifying guidelines by vaccination status was €599 (2/4vHPV) and €725 (9vHPV) per vaccinated woman. Consequently, for the first birth cohort of ∼22,000 women who were vaccinated in adolescence in Norway, between €10.5-13.2 million over their lifetime could be spent on identifying individual vaccination status and stratify screening while remaining cost-effective.

CONCLUSION

Less intensive strategies are required for CC screening to remain cost-effective in HPV-vaccinated women. Moreover, screening can remain cost-effective even if large investments are made to identify individual vaccination status and stratify screening guidelines accordingly.

Effect of Cervical Cancer Screening Programs on Preterm Birth: A Decision and Cost-Effectiveness Analysis

OBJECTIVE

To assess the effect of age at initiation and interval of cervical cancer screening in women of reproductive age on the risk of future preterm birth and subsequent adverse neonatal outcome relative to maternal life-years gained and cost of both screening and preterm birth.

METHODS

In this decision and cost-effectiveness analysis, we compared eight cytology-based screening programs varying in age of onset (21, 24, 25, 27, or 30 years) and screening interval (3 or 5 years) in a fictive cohort of 100,000 women. We used the microsimulation screening analysis model to estimate number of cervical intraepithelial neoplasia diagnoses, large loop excisions of the transformation zone (LLETZs), life-years gained, cervical cancer cases, deaths, and costs of screening and treatment. We used the number of LLETZs to calculate additional preterm births, subsequent neonatal morbidity, mortality, and associated costs.

RESULTS

The number of LLETZs per 100,000 women varied from 9,612 for the most intensive screening (every 3 years from age 21 years) to 4,646 for the least intensive screening (every 5 years from age 30 years). Compared with the least intensive program, the most intensive program increased maternal life-years gained by 9% (10,728 compared with 9,839), decreased cervical cancer cases by 67% (52 compared with 158), and cervical cancer deaths by 75% (four compared with 16) at the expense of 250% (158 compared with 45) more preterm births and 320% (four compared with one) more neonatal deaths while increasing total costs by $55 million ($77 compared with $23 million). The number of maternal life-years gained per additional preterm birth varied from 68 to 258 with subsequent total costs per maternal life-years gained of $7,212 and $2,329.

CONCLUSION

Cervical cancer screening every 3 years and subsequent treatment in women aged younger than 30 years yield limited life-years but may have substantial perinatal adverse effects. Consequently, women who plan to have children may benefit from a more cautious screening approach, taking into account their risk for both cancer and preterm birth.

Systematic review of cost-effectiveness analyses for combinations of prevention strategies against human papillomavirus (HPV) infection: a general trend

BACKGROUND

Due to the arrival of multi-valent HPV vaccines, it is more and more important to have a better understanding of the relationship between vaccination and screening programmes. This review aimed to: (1) collect published evidence on the cost-effectiveness profile of different HPV prevention strategies and, in particular, those combining vaccination with changes in screening practices; (2) explore the cost-effectiveness of alternative preventive strategies based on screening and vaccination.

METHODS

A systematic literature review was conducted in order to identify the relevant studies regarding the cost-effectiveness of prevention strategies against HPV infection. Analysis comparing the modelling approaches between studies was made along with an assessment of the magnitude of impact of several factors on the cost-effectiveness of different screening strategies.

RESULTS

A total of 18 papers were quantitatively summarised within the narrative. A high degree of heterogeneity was found in terms of how HPV prevention strategies have been assessed in terms of their economic and epidemiological impact, with variation in screening practice and valence of HPV vaccination found to have large implications in terms of cost-effectiveness.

CONCLUSIONS

This review demonstrated synergies between screening and vaccination. New prevention strategies involving multi-valence vaccination, HPV DNA test screening, delayed commencement and frequency of screening could be implemented in the future. Strategies implemented in the future should be chosen with care, and informed knowledge of the potential impact of all possible prevention strategies. Highlighted in this review is the difficulty in assessing multiple strategies. Appropriate modelling techniques will need to be utilised to assess the most cost-effective strategies.