The Natural Disease Course of Pancreatic Cyst-Associated Neoplasia, Dysplasia, and Ductal Adenocarcinoma: Results of a Microsimulation Model

BACKGROUND & AIMS

Estimates on the progression of precursor lesions to pancreatic cancer (PC) are scarce. We used microsimulation modeling to gain insight into the natural disease course of PC and its precursors. This information is pivotal to explore the efficacy of PC screening.

METHODS

A Microsimulation Screening Analysis model was developed in which pancreatic intraepithelial neoplasms and cysts can evolve from low-grade dysplasia (LGD) to high-grade dysplasia (HGD) to PC. The model was calibrated to Dutch PC incidence data and Japanese precursor prevalence data (autopsy cases without PC) and provides estimates of PC progression (precursor lesion onset and stage duration).

RESULTS

Mean LGD state durations of cysts and pancreatic intraepithelial neoplasms were 15.8 years and 17.1 years, respectively. Mean HGD state duration was 5.8 years. For lesions that progress to PC, the mean duration was 4.8-4.9 years for LGD lesions and 4.0-4.1 years for HGD lesions. In 13.7% of individuals who developed PC, the HGD state lasted less than 1 year. The probability that an individual at age 50 years developed PC in the next 20 years was estimated to be 1.8% in the presence of any cyst and 6.1% in case of an LGD mucinous cyst. This 20-year PC risk was estimated to be 5.1% for individuals with an LGD pancreatic intraepithelial neoplasm.

CONCLUSIONS

Mean duration of HGD lesions before development of PC was estimated to be 4.0 years. This implies a window of opportunity for screening, presuming the availability of a reliable diagnostic test. The probability that an LGD cyst will progress to cancer was predicted to be low.

Projections of costs and quality adjusted life years lost due to dementia from 2020 to 2050: A population-based microsimulation study

INTRODUCTION

Efficient healthcare planning requires reliable projections of the future increase in costs and quality-adjusted life years (QALYs) lost due to dementia.

METHODS

We used the microsimulation model MISCAN-Dementia to simulate life histories and dementia occurrence using population-based Rotterdam Study data and nationwide birth cohort demographics. We estimated costs and QALYs lost in the Netherlands from 2020 to 2050, incorporating literature estimates of cost and utility for patients and caregivers by dementia severity and care setting.

RESULTS

Societal costs and QALYs lost due to dementia are estimated to double between 2020 and 2050. Costs are incurred predominantly through institutional (34%), formal home (31%), and informal home care (20%). Lost QALYs are mostly due to shortened life expectancy (67%) and, to a lesser extent, quality of life with severe dementia (14%).

DISCUSSION

To limit healthcare costs and quality of life losses due to dementia, interventions are needed that slow symptom progression and reduce care dependency.

Acceptability of risk-based triage in cervical cancer screening: A focus group study

BACKGROUND

Compared to the previous cytology-based program, the introduction of primary high-risk human papillomavirus (hrHPV) based screening in 2017 has led to an increased number of referrals. To counter this, triage of hrHPV-positive women in cervical cancer screening can potentially be optimized by taking sociodemographic and lifestyle risk factors for cervical abnormalities into account. Therefore, it is essential to gain knowledge of the views of women (30-60 years) eligible for cervical cancer screening.

OBJECTIVE

The main goal of this qualitative study was to gain insight in the aspects that influence acceptability of risk-based triage in cervical cancer screening.

DESIGN

A focus group study in which participants were recruited via four general medical practices, and purposive sampling was used to maximize heterogeneity with regards to age, education level, and cervical cancer screening experiences.

APPROACH

The focus group discussions were transcribed verbatim and analyzed using reflexive thematic analysis.

PARTICIPANTS

A total of 28 women (average age: 45.2 years) eligible for cervical cancer screening in The Netherlands participated in seven online focus group discussions. Half of the participants was higher educated, and the participants differed in previous cervical cancer screening participation and screening result.

KEY RESULTS

In total, 5 main themes and 17 subthemes were identified that determine the acceptability of risk-stratified triage. The main themes are: 1) adequacy of the screening program: an evidence-based program that is able to minimize cancer incidence and reduce unnecessary referrals; 2) personal information (e.g., sensitive topics and stigma); 3) emotional impact: fear and reassurance; 4) communication (e.g., transparency); and 5) autonomy (e.g., prevention).

CONCLUSION

The current study highlights several challenges regarding the development and implementation of risk-based triage that need attention in order to be accepted by the target group. These challenges include dealing with sensitive topics and a transparent communication strategy.

The impact of pancreatic cancer screening on life expectancy: A systematic review of modeling studies

Evidence supporting the effectiveness of pancreatic cancer (PC) screening is scant. Most clinical studies concern small populations with short follow-up durations. Mathematical models are useful to estimate long-term effects of PC screening using short-term indicators. This systematic review aims to evaluate the impact of PC screening on life expectancy (LE) in model-based studies. Therefore, we searched four databases (Embase, Medline, Web-of-science, Cochrane) until 30 May 2022 to identify model-based studies evaluating the impact of PC screening on LE in different risk populations. Two authors independently screened identified papers, extracted data and assessed the methodological quality of studies. A descriptive analysis was performed and the impact of screening strategies on LE of different risk groups was reported. Our search resulted in 419 studies, of which eight met the eligibility criteria (mathematical model, PC screening, LE). Reported relative risks (RR) for PC varied from 1 to 70. In higher risk individuals (RR > 5), annual screening (by imaging with 56% sensitivity for HGD/early stage PC) predicted to increase LE of screened individuals by 20 to 260 days. In the general population, one-time PC screening was estimated to decrease LE (2-110 days), depending on the test characteristics and treatment mortality risk. In conclusion, although the models use different and sometimes outdated or unrealistic assumptions, it seems that PC screening in high-risk populations improves LE, and that this gain increases with a higher PC risk. Updated model studies, with data from large clinical trials are necessary to predict the long-term effect of PC screening more accurately.

Sociodemographic Characteristics and Screening Outcomes of Women Preferring Self-Sampling in the Dutch Cervical Cancer Screening Programme: A Population-Based Study

BACKGROUND

In the Netherlands, lower high-risk human papillomavirus (hrHPV) positivity but higher cervical intraepithelial neoplasia (CIN) 2+ detection were found in self-collected compared with clinician-collected samples. To investigate the possible reason for these differences, we compared sociodemographic and screening characteristics of women and related these to screening outcomes.

METHODS

We extracted data from PALGA on all primary hrHPV screens and associated follow-up tests for 857,866 screened women, invited in 2017 and 2018. We linked these data with sociodemographic data from Statistics Netherlands. Logistic regression was performed for hrHPV positivity and CIN 2+/3+ detection.

RESULTS

Out of the 857,866 women, 6.8% chose to use a self-sampling device. A higher proportion of self-sampling users was ages 30 to 35 years, was not previously screened, was living in a one-person household, or was the breadwinner in the household. After adjustment for these factors self-sampling had lower hrHPV positivity (aOR, 0.65; 95% CI, 0.63-0.68)) as compared with clinician-collected sampling, as well as lower odds of CIN 2+ (aOR, 0.76; 95% CI, 0.70-0.82) and CIN 3+ (aOR, 0.86; 95% CI, 0.78-0.95) detection.

CONCLUSIONS

It is likely that the observed differences between the two sampling methods are not only related to sociodemographic differences, but related to differences in screening test accuracy and/or background risk.

IMPACT

Self-sampling can be used for targeting underscreened women, as a more convenient screening tool. Further investigation is required to evaluate how to implement self-sampling, when it is used as a primary instrument in routine screening. See related commentary by Arbyn et al., p. 159.

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.

Health impacts of COVID-19 disruptions to primary cervical screening by time since last screen: A model-based analysis for current and future disruptions

Background

We evaluated how temporary disruptions to primary cervical cancer (CC) screening services may differentially impact women due to heterogeneity in their screening history and test modality.

Methods

We used three CC models to project the short- and long-term health impacts assuming an underlying primary screening frequency (i.e., 1, 3, 5, or 10 yearly) under three alternative COVID-19-related screening disruption scenarios (i.e., 1-, 2- or 5-year delay) versus no delay, in the context of both cytology-based and HPV-based screening.

Results

Models projected a relative increase in symptomatically-detected cancer cases during a 1-year delay period that was 38% higher (Policy1-Cervix), 80% higher (Harvard) and 170% higher (MISCAN-Cervix) for under-screened women whose last cytology screen was 5 years prior to the disruption period compared with guidelines-compliant women (i.e., last screen three years prior to disruption). Over a woman's lifetime, temporary COVID-19-related delays had less impact on lifetime risk of developing CC than screening frequency and test modality; however, CC risks increased disproportionately the longer time had elapsed since a woman's last screen at the time of the disruption. Excess risks for a given delay period were generally lower for HPV-based screeners than for cytology-based screeners.

Conclusions

Our independent models predicted that the main drivers of CC risk were screening frequency and screening modality, and the overall impact of disruptions from the pandemic on CC outcomes may be small. However, screening disruptions disproportionately affect under-screened women, underpinning the importance of reaching such women as a critical area of focus, regardless of temporary disruptions.

Funding

This study was supported by funding from the National Cancer Institute (U01CA199334). The contents are solely the responsibility of the authors and do not necessarily represent the official views of the National Cancer Institute. Megan A Smith receives salary support from the National Health and Medical Research Council, Australia (APP1159491) and Cancer Institute NSW (ECF181561). Matejka Rebolj is funded by Cancer Research UK (reference: C8162/A27047). James O'Mahony is funded by Ireland's Health Research Board (EIA2017054). Karen Canfell receives salary support from the National Health and Medical Research Council, Australia (APP1194679). Emily A. Burger receives salary support from the Norwegian Cancer Society.

Projected prevalence and incidence of dementia accounting for secular trends and birth cohort effects: a population-based microsimulation study

There is need for accurate projections of the future dementia burden to prepare healthcare systems and policymakers. Existing projections only account for population ageing, not for observed declines in age-specific dementia incidence of 13% per decade. We developed a dementia microsimulation model that synthesizes population-based data from the Rotterdam Study with changes in demographics between birth cohorts from the early 1900s onwards. We determined dementia prevalence and incidence until 2050 for three different dementia incidence trend scenarios: (1) stable age-specific incidence, (2) linear decline by 13% per decade, (3) nonlinear declines averaging 13% per decade. Assuming a stable age-specific incidence resulted in a 130% increase in incidence and 118% in prevalence between 2020 and 2050. By contrast, the linearly declining trend resulted in substantially smaller increases of 58% in incidence (95%CI: 29–87%), and 43% in prevalence (95%CI: 13–66%), corresponding to 39% lower incidence and 36% lower prevalence by 2050 than in the stable-incidence scenario. Results for various non-linear declines fell between the stable and linear trend. The future burden of dementia is highly susceptible to achievable changes in age-specific incidence. Extension of previously established secular trends globally would reduce widely upheld projections of new dementia cases until 2050 by 39%.

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.

Heterogeneity in Reports of Dementia Disease Duration and Severity: A Review of the Literature

BACKGROUND

The burden of dementia is changing due to population aging and changes in incidence and risk factor profiles. Reliable projections of future disease burden require accurate estimates of disease duration across different stages of dementia severity.

OBJECTIVE

To provide an overview of current evidence on severity stage and disease duration in patients with dementia.

METHODS

We reviewed the literature on duration of mild cognitive impairment (MCI), dementia, and various dementia severity stages. Data on study setting, country, sample size, severity stages, dementia type, and definition of disease duration was collected. Weighted averages and Q-statistics were calculated within severity stages and duration definitions.

RESULTS

Of 732 screened articles, 15 reported the duration of one or more severity stages and only half of those reported severity stage onset to conversion to the following stage. In those studies, MCI, very mild dementia, and mild dementia stages lasted 3-4 years and moderate and severe dementia stages lasted 1-2 years. Information on the disease duration was reported in 93 (13%) of screened articles and varied from 1 to 17 years. Reporting of dementia severity stage and disease duration in the literature was highly heterogeneous, which was accounted for only in part by dementia type, study setting, or continent of data collection.

CONCLUSION

The duration of dementia disease stages shortens with advancing stage. However, reliable modelling of future dementia burden and informing of intervention strategies will require more consistently reported duration estimates from studies that follow individuals longitudinally throughout their entire disease course.

Impact of disruptions and recovery for established cervical screening programs across a range of high-income country program designs, using COVID-19 as an example: A modelled analysis

COVID-19 has disrupted cervical screening in several countries, due to a range of policy-, health-service and participant-related factors. Using three well-established models of cervical cancer natural history adapted to simulate screening across four countries, we compared the impact of a range of standardised screening disruption scenarios in four countries that vary in their cervical cancer prevention programs. All scenarios assumed a 6- or 12-month disruption followed by a rapid catch-up of missed screens. Cervical screening disruptions could increase cervical cancer cases by up to 5-6%. In all settings, more than 60% of the excess cancer burden due to disruptions are likely to have occurred in women aged less than 50 years in 2020, including settings where women in their 30s have previously been offered HPV vaccination. Approximately 15-30% of cancers predicted to result from disruptions could be prevented by maintaining colposcopy and precancer treatment services during any disruption period. Disruptions to primary screening had greater adverse effects in situations where women due to attend for screening in 2020 had cytology (vs. HPV) as their previous primary test. Rapid catch-up would dramatically increase demand for HPV tests in 2021, which it may not be feasible to meet because of competing demands on the testing machines and reagents due to COVID tests. These findings can inform future prioritisation strategies for catch-up that balance potential constraints on resourcing with clinical need.

Molecular markers for cervical cancer screening

INTRODUCTION

Cervical cancer remains a significant healthcare problem, notably in low- to middle-income countries. While a negative test for hrHPV has a predictive value of more than 99.5%, its positive predictive value is less than 10% for CIN2+ stages. This makes the use of a so-called triage test indispensable for population-based screening to avoid referring women, that are ultimately at low risk of developing cervical cancer, to a gynecologist. This review will give an overview of tests that are based on epigenetic marker panels and protein markers.

AREAS COVERED

There is a medical need for molecular markers with a better predictive value to discriminate hrHPV-positive women that are at risk of developing cervical cancer from those that are not. Areas covered are epigenetic and protein markers as well as health economic considerations in view of the fact that most cases of cervical cancer arise in low-to-middle-income countries.

EXPERT OPINION

While there are biomarker assays based on changes at the nucleic acid (DNA methylation patterns, miRNAs) and at the protein level, they are not widely used in population screening. Combining nucleic acid-based and protein-based tests could improve the overall specificity for discriminating CIN2+ lesions that carry a low risk of progressing to cervical cancer within the screening interval from those that carry an elevated risk. The challenge is to reduce unnecessary referrals without an undesired increase in false-negative diagnoses resulting in cases of cervical cancer that could have been prevented. A further challenge is to develop tests for low-and middle-income countries, which is critical to reduce the worldwide burden of cervical cancer.

Modeling Strategies to Optimize Cancer Screening in USPSTF Guideline-Noncompliant Women

Importance

In 2018, only half of US women obtained all evidence-based cancer screenings. This proportion may have declined during the COVID-19 pandemic because of social distancing, high-risk factors, and fear.

Objective

To evaluate optimal screening strategies in women who obtain some, but not all, US Preventive Services Task Force (USPSTF)-recommended cancer screenings.

Design, Setting, and Participants

This modeling study was conducted from January 31, 2017, to July 20, 2020, and used 4 validated mathematical models from the National Cancer Institute's Cancer Intervention and Surveillance Modeling Network using data from 20 million simulated women born in 1965 in the US.

Interventions

Forty-five screening strategies were modeled that combined breast, cervical, colorectal, and/or lung cancer (LC) screenings; restricted to 1, 2, 3 or 4 screenings per year; or all eligible screenings once every 5 years.

Main Outcomes and Measures

Modeled life-years gained from restricted cancer screenings as a fraction of those attainable from full compliance with USPSTF recommendations (maximum benefits). Results were stratified by LC screening eligibility (LC-eligible/ineligible). We repeated the analysis with 2018 adherence rates, evaluating the increase in adherence required for restricted screenings to have the same population benefit as USPSTF recommendations.

Results

This modeling study of 20 million simulated US women found that it was possible to reduce screening intensity to 1 carefully chosen test per year in women who were ineligible for LC screening and 2 tests per year in eligible women while maintaining 94% or more of the maximum benefits. Highly ranked strategies screened for various cancers, but less often than recommended by the USPSTF. For example, among LC-ineligible women who obtained just 1 screening per year, the optimal strategy frequently delayed breast and cervical cancer screenings by 1 year and skipped 3 mammograms entirely. Among LC-eligible women, LC screening was essential; strategies omitting it provided 25% or less of the maximum benefits. The top-ranked strategy restricted to 2 screenings per year was annual LC screening and alternating fecal immunochemical test with mammography (skipping mammograms when due for cervical cancer screening, 97% of maximum benefits). If adherence in a population of LC-eligible women obtaining 2 screenings per year were to increase by 1% to 2% (depending on the screening test), this model suggests that it would achieve the same benefit as USPSTF recommendations at 2018 adherence rates.

Conclusions and Relevance

This modeling study of 45 cancer screening strategies suggests that women who are noncompliant with cancer screening guidelines may be able to reduce USPSTF-recommended screening intensity with minimal reduction in overall benefits.

Cervical screening during the COVID-19 pandemic: optimising recovery strategies

Disruptions to cancer screening services have been experienced in most settings as a consequence of the COVID-19 pandemic. Ideally, programmes would resolve backlogs by temporarily expanding capacity; however, in practice, this is often not possible. We aim to inform the deliberations of decision makers in high-income settings regarding their cervical cancer screening policy response. We caution against performance measures that rely solely on restoring testing volumes to pre-pandemic levels because they will be less effective at mitigating excess cancer diagnoses than will targeted measures. These measures might exacerbate pre-existing inequalities in accessing cervical screening by disregarding the risk profile of the individuals attending. Modelling of cervical screening outcomes before and during the pandemic supports risk-based strategies as the most effective way for screening services to recover. The degree to which screening is organised will determine the feasibility of deploying some risk-based strategies, but implementation of age-based risk stratification should be universally feasible.

Estimating the Natural History of Cervical Carcinogenesis Using Simulation Models: A CISNET Comparative Analysis

BACKGROUND

The natural history of human papillomavirus (HPV)-induced cervical cancer (CC) is not directly observable, yet the age of HPV acquisition and duration of preclinical disease (dwell time) influences the effectiveness of alternative preventive policies. We performed a Cancer Intervention and Surveillance Modeling Network (CISNET) comparative modeling analysis to characterize the age of acquisition of cancer-causing HPV infections and implied dwell times for distinct phases of cervical carcinogenesis.

METHODS

Using four CISNET-cervical models with varying underlying structures but fit to common US epidemiological data, we estimated the age of acquisition of causal HPV infections and dwell times associated with three phases of cancer development: HPV, high-grade precancer, and cancer sojourn time. We stratified these estimates by HPV genotype under both natural history and CC screening scenarios, because screening prevents cancer development that affects the mix of detected cancers.

RESULTS

The median time from HPV acquisition to cancer detection ranged from 17.5 to 26.0 years across the four models. Three models projected that 50% of unscreened women acquired their causal HPV infection between ages 19 and 23 years, whereas one model projected these infections occurred later (age 34 years). In the context of imperfect compliance with US screening guidelines, the median age of causal infection was 4.4-15.9 years later compared with model projections in the absence of screening.

CONCLUSIONS

These validated CISNET-CC models, which reflect some uncertainty in the development of CC, elucidate important drivers of HPV vaccination and CC screening policies and emphasize the value of comparative modeling when evaluating public health policies.

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.

Identifying key factors for the effectiveness of pancreatic cancer screening: A model-based analysis

Pancreatic cancer (PC) survival is poor, as detection usually occurs late, when treatment options are limited. Screening of high‐risk individuals may enable early detection and a more favorable prognosis. Knowledge gaps prohibit establishing the effectiveness of screening. We developed a Microsimulation Screening Analysis model to analyze the impact of relevant uncertainties on the effect of PC screening in high‐risk individuals. The model simulates two base cases: one in which lesions always progress to PC and one in which indolent and faster progressive lesions coexist. For each base case, the effect of annual and 5‐yearly screening with endoscopic ultrasonography/magnetic resonance imaging was evaluated. The impact of variance in PC risk, screening test characteristics and surgery‐related mortality was evaluated using sensitivity analyses. Screening resulted in a reduction of PC mortality by at least 16% in all simulated scenarios. This reduction depended strongly on the natural disease course (annual screening: −57% for “Progressive‐only” vs −41% for “Indolent Included”). The number of screen and surveillance tests needed to prevent one cancer death was impacted most by PC risk. A 10% increase in test sensitivity reduced mortality by 1.9% at most. Test specificity is important for the number of surveillance tests. In conclusion, screening reduces PC mortality in all modeled scenarios. The natural disease course and PC risk strongly determines the effectiveness of screening. Test sensitivity seems of lesser influence than specificity. Future research should gain more insight in PC pathobiology to establish the true value of PC screening in high‐risk individuals.

What's new?

About 10 percent of pancreatic cancers occur in individuals with inherited risk factors. While screening such high‐risk individuals can facilitate the detection of precursor lesions and early‐stage cancer, the extent to which benefits outweigh harms, including overdiagnosis, remains unknown. Here, using a microsimulation model, the authors explored uncertainties concerning the early detection of pancreatic cancer and analyzed the impact of these uncertainties on the effect of screening. In all simulated scenarios, screening was associated with reduced pancreatic cancer mortality. The effectiveness of screening was most strongly impacted by characteristics of natural disease course and level of pancreatic cancer risk

Risk of Gynecologic Cancer after Atypical Glandular Cells Found on Cervical Cytology: A Population-Based Cohort Study

BACKGROUND

Atypical glandular cells (AGC) are rare abnormalities found on cervical cytology associated with a range of lesions of the female reproductive system. We compared the risk of cervical and other gynecologic cancers following AGC on cervical cytology with the risk following squamous cell abnormalities of comparable severity.

METHODS

We used data from the Dutch Pathology Archive (PALGA) from 2000 to 2015 to categorize cervical cytology tests into groups based on most severe cytologic abnormality and correlated follow-up advice (normal cytology and "no follow-up" advice, squamous-cell-based, AGC-based, and combined AGC/squamous-cell based each with either repeat testing or referral advice). Cancer data were linked from the Netherlands Cancer Registry. Cox proportional hazard models were calculated stratified by age [younger (<50 years) and older (50+ years)], adjusted for number of previous primary cytology tests.

RESULTS

8,537,385 cytology smears and 9,061 cancers were included. When repeat cytology testing was advised, HRs of cervical cancer (younger women: HR, 6.91; 95% CI, 5.48-8.71; older women: HR, 3.98; 95% CI, 2.38-6.66) or other gynecologic cancer diagnosis in younger women (HR, 2.82; 95% CI, 1.39-5.74) were significantly higher after an AGC-based abnormality compared with squamous-based abnormalities. Hazards were also significantly higher for "referral" advice cytology, except for cervical cancer among older women (HR, 0.88; 95% CI, 0.63-1.21).

CONCLUSIONS

AGC indicates an increased risk of gynecologic cancer compared with squamous-based abnormalities of comparable severity.

IMPACT

Gynecologists should be alert for cervical and endometrial cancers when examining women referred following AGC.

Reducing unnecessary referrals for colposcopy in hrHPV-positive women within the Dutch cervical cancer screening programme: A modelling study

BACKGROUND

With the implementation of primary high-risk human papillomavirus (hrHPV) screening in the Netherlands, an increase was observed in the number of unnecessary referrals (≤Cervical Intraepithelial Neoplasia (CIN) 1) to colposcopy. We aimed to investigate which alternative triage strategies safely reduce unnecessary referrals in HPV-based cervical cancer screening programmes.

METHODS

Microsimulation model MISCAN was used to simulate an unvaccinated cohort of ten million 30-year old Dutch women. We calculated unnecessary referrals, cervical cancer incidence, mortality, costs and QALYs for 24 triage strategies. Condition for direct referral (atypical squamous cells of undetermined significance (ASC-US), low-grade squamous intraepithelial lesions (LSIL), high-grade squamous intraepithelial lesions (HSIL), conditional on HPV-genotype 16/18/other high risk (OHR)), type of triage test (cytology alone or combined with hrHPV) and time to triage test (6 or 12 months) was varied.

RESULTS

The 24 triage strategies had varying effects on the number of unnecessary referrals ranging from -72% to +35%. Adjusting conditions for referral to 'HPV16/18+ and ASC-US+' and 'HPVOHR+ and HSIL+' and extending the interval between tests to 12 months resulted in a reduction in unnecessary referrals of 40% (incidence +0%, mortality -1%). Reduction in unnecessary referrals without genotyping was achieved by adjusting conditions for direct referral to LSIL (12 months to repeat test) (unnecessary referrals -37%, incidence +2%, mortality +0%).

CONCLUSIONS

To reduce the number of unnecessary referrals without increasing incidence and mortality by more than 2% in the Dutch cervical cancer screening programme, genotyping for HPV16 or HPV16/18 should be implemented with 12 months to repeat testing.

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.

Mapping the multicausality of Alzheimer's disease through group model building

Alzheimer’s disease (AD) is a complex, multicausal disorder involving several spatiotemporal scales and scientific domains. While many studies focus on specific parts of this system, the complexity of AD is rarely studied as a whole. In this work, we apply systems thinking to map out known causal mechanisms and risk factors ranging from intracellular to psychosocial scales in sporadic AD. We report on the first systemic causal loop diagram (CLD) for AD, which is the result of an interdisciplinary group model building (GMB) process. The GMB was based on the input of experts from multiple domains and all proposed mechanisms were supported by scientific literature. The CLD elucidates interaction and feedback mechanisms that contribute to cognitive decline from midlife onward as described by the experts. As an immediate outcome, we observed several non-trivial reinforcing feedback loops involving factors at multiple spatial scales, which are rarely considered within the same theoretical framework. We also observed high centrality for modifiable risk factors such as social relationships and physical activity, which suggests they may be promising leverage points for interventions. This illustrates how a CLD from an interdisciplinary GMB process may lead to novel insights into complex disorders. Furthermore, the CLD is the first step in the development of a computational model for simulating the effects of risk factors on AD.

The potential of breast cancer screening in Europe

Currently, all European countries offer some form of breast cancer screening. Nevertheless, disparities exist in the status of implementation, attendance and the extent of opportunistic screening. As a result, breast cancer screening has not yet reached its full potential. We examined how many breast cancer deaths could be prevented if all European countries would biennially screen all women aged 50 to 69 for breast cancer. We calculated the number of breast cancer deaths already prevented due to screening as well as the number of breast cancer deaths which could be additionally prevented if the total examination coverage (organised plus opportunistic) would reach 100%. The calculations are based on total examination coverage in women aged 50 to 69, the annual number of breast cancer deaths for women aged 50 to 74 and the maximal possible mortality reduction from breast cancer, assuming similar effectiveness of organised and opportunistic screening. The total examination coverage ranged from 49% (East), 62% (West), 64% (North) to 69% (South). Yearly 21 680 breast cancer deaths have already been prevented due to mammography screening. If all countries would reach 100% examination coverage, 12 434 additional breast cancer deaths could be prevented annually, with the biggest potential in Eastern Europe. With maximum coverage, 23% of their breast cancer deaths could be additionally prevented, while in Western Europe it could be 21%, in Southern Europe 15% and in Northern Europe 9%. Our study illustrates that by further optimising screening coverage, the number of breast cancer deaths in Europe can be lowered substantially.

Historical and projected hysterectomy rates in the USA: Implications for future observed cervical cancer rates and evaluating prevention interventions

BACKGROUND

SEER-reported cervical cancer incidence rates reflect the total female population including women no longer at risk due to hysterectomy. Hysterectomy rates have been declining in the United States as alternative treatments have become available, which could result in an apparent increase in SEER-reported cervical cancer rates. We aimed to obtain nationally representative historical data on hysterectomy rates in USA, use trends analysis to project rates back to 1935 and forward to 2035, and then predict the impact of changing hysterectomy rates on SEER-reported cervical cancer rates.

METHODS

We performed a systematic search of Medline, Embase, Premedline, Cochrane Central databases and extracted nationally-representative hysterectomy incidence data from 1965 to 2009, including data on the number of cervix-preserving (subtotal) procedures. We then projected rates back to 1935, and forward to 2035 based on trends from joinpoint regression. These rates were then used to estimate hysterectomy prevalence out to 2035, and then to predict the impact of changing hysterectomy rates on SEER-reported cervical cancer rates to 2035. We examined alternative assumptions regarding projected hysterectomy incidence rates out to 2035, including a scenario in which rates decline no further from 2009 rates, and a scenario where rates decline at twice the baseline rate.

RESULTS

Estimated age-standardized hysterectomy incidence increased from 2.4 to 10.6 per 1000 women between 1935 and 1975. Thereafter, rates are predicted to fall to 3.9 per 1000 by 2035. Subtotal hysterectomy procedures declined from being the predominant method in 1935 to less than 12% of procedures from 1970 onwards. Consequently, holding all else constant, an increase in SEER-reported age-standardized cervical cancer incidence rates (ages 0-85+) of 9% is expected from 2009 to 2035. The predictions were minimally impacted by alternative scenarios for future hysterectomy rates.

CONCLUSIONS

Declining hysterectomy rates have implications for the interpretation of SEER-reported cervical cancer rates. A background increase in cervical cancer rates due to decreasing population hysterectomy exposure may partially offset expected decreases from recent cervical screening changes recommended by the US Preventive Services Task Force. Evaluations of new cervical cancer prevention opportunities should consider the background impact of historical and projected hysterectomy rates.

The Impact of Different Screening Model Structures on Cervical Cancer Incidence and Mortality Predictions: The Maximum Clinical Incidence Reduction (MCLIR) Methodology

Background. To interpret cervical cancer screening model results, we need to understand the influence of model structure and assumptions on cancer incidence and mortality predictions. Cervical cancer cases and deaths following screening can be attributed to 1) (precancerous or cancerous) disease that occurred after screening, 2) disease that was present but not screen detected, or 3) disease that was screen detected but not successfully treated. We examined the relative contributions of each of these using 4 Cancer Intervention and Surveillance Modeling Network (CISNET) models. Methods. The maximum clinical incidence reduction (MCLIR) method compares changes in the number of clinically detected cervical cancers and mortality among 4 scenarios: 1) no screening, 2) one-time perfect screening at age 45 that detects all existing disease and delivers perfect (i.e., 100% effective) treatment of all screen-detected disease, 3) one-time realistic-sensitivity cytological screening and perfect treatment of all screen-detected disease, and 4) one-time realistic-sensitivity cytological screening and realistic-effectiveness treatment of all screen-detected disease. Results. Predicted incidence reductions ranged from 55% to 74%, and mortality reduction ranged from 56% to 62% within 15 years of follow-up for scenario 4 across models. The proportion of deaths due to disease not detected by screening differed across the models (21%–35%), as did the failure of treatment (8%–16%) and disease occurring after screening (from 1%–6%). Conclusions. The MCLIR approach aids in the interpretation of variability across model results. We showed that the reasons why screening failed to prevent cancers and deaths differed between the models. This likely reflects uncertainty about unobservable model inputs and structures; the impact of this uncertainty on policy conclusions should be examined via comparing findings from different well-calibrated and validated model platforms.

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.

Management and treatment of cervical intraepithelial neoplasia in the Netherlands after referral for colposcopy

Introduction

The aim of this study was to describe trends in the diagnosis and treatment of women referred from the national screening program with cervical intraepithelial neoplasia (CIN) in the Netherlands, and to compare these trends with national guidelines and identify potential areas for improvement for the new primary high‐risk HPV screening program.

Material and methods

We conducted a population‐based cohort study using data from the Dutch pathology archive. Women aged 29‐63 years who took part in the Dutch cervical screening program between 1 January 2005 and 31 December 2014 were selected. Three referral groups were identified: direct referrals and those referred after either one (first indirect referrals) or two (second indirect referrals) repeat cytology tests, totaling 85 239 referrals for colposcopy. The most invasive management technique and the most severe diagnosis of each screening episode was identified. Rates of management techniques were calculated separately by referral type, highest CIN diagnosis and age group.

Results

In all, 85.1% of CIN 3 lesions were treated with excision (either large excision or hysterectomy) and 26.4% of CIN 1 lesions were treated with large excision. Rates of overtreatment (CIN 1 or less) in see‐and‐treat management were higher for indirect referrals than for direct referrals and increased with age. Large excision rates increased with CIN diagnosis severity.

Conclusions

Despite guideline recommendations not to treat, CIN 1 lesions were treated in just over 25% of cases and approximately 15% of CIN 3 lesions were possibly undertreated. Given the expected increase in CIN detection in the new primary high‐risk HPV screening program, reduction in CIN 1 treatment and CIN 2 treatment in younger women is needed to avoid an increase in potential harm.

Identifying the barriers to effective breast, cervical and colorectal cancer screening in thirty one European countries using the Barriers to Effective Screening Tool (BEST)

The aim of this study was to identify barriers to effective breast, cervical and colorectal cancer screening programmes throughout the whole of the European region using the Barriers to Effective Screening Tool (BEST). The study was part of the scope of the EU-TOPIA (TOwards imProved screening for breast, cervical and colorectal cancer In All of Europe) project and respondents were European screening organisers, researchers and policymakers taking part in a workshop for the project in Budapest in September 2017. 67 respondents from 31 countries responded to the online survey. The study found that there are many barriers to effective screening throughout the system from identification of the eligible population to ensuring appropriate follow-up and treatment for the three cancers. The most common barriers were opportunistic screening, sub-optimal participation, limited capacity (including trained human resource), inadequate and/or disjointed information technology systems and complex administration procedures. Many of the barriers were reported consistently across different countries. This study identified the barriers that, in general, require further investment of resources.

Quality of life assumptions determine which cervical cancer screening strategies are cost-effective

Quality-adjusted life years are used in cost-effectiveness analyses (CEAs). To calculate QALYs, a "utility" (0-1) is used for each health state induced or prevented by the intervention. We aimed to estimate the impact of quality of life (QoL) assumptions (utilities and durations of health states) on CEAs of cervical cancer screening. To do so, 12 alternative sets of utility assumptions were retrieved from published cervical cancer screening CEAs. Two additional sets were based on empirical QoL data that were integrally obtained through two different measures (SF-6D and EQ-5D) from eight groups of women (total n = 3,087), from invitation for screening to diagnosis with cervical cancer. Per utility set we calculated the number of quality-adjusted days lost (QADL) for each relevant health state in cervical cancer screening, by multiplying the study-specific assumed disutilities (i.e., 1-utility) with study-specific durations of the loss in QoL, resulting in 14 "QADL-sets." With microsimulation model MISCAN we calculated cost-effectiveness of 342 alternative screening programs (varying in primary screening test [Human Papillomavirus (HPV) vs. cytology], starting ages, and screening interval) for each of the 14 QADL-sets. Utilities used in CEAs appeared to differ largely. We found that ten QADL-sets from the literature resulted in HPV and two in cytology as preferred primary test. The SF-6D empirical QADL-set resulted in cytology and the EQ-5D one in HPV as preferred primary test. In conclusion, assumed utilities and health state durations determine cost-effectiveness of cervical cancer screening. Also, the measure used to empirically assess utilities can be crucial for CEA conclusions.

Harms of cervical cancer screening in the United States and the Netherlands

We studied harms related to cervical cancer screening and management of screen-positive women in the United States (US) and the Netherlands. We utilized data from four US integrated health care systems (SEARCH), the US National Health Interview Survey, New Mexico state, the Netherlands national histopathology registry, and included studies on adverse health effects of cervical screening. We compared the number of Papanicolaou (Pap) smear tests, abnormal test results, punch biopsies, treatments, health problems (anxiety, pain, bleeding and discharge) and preterm births associated with excisional treatments. Results were age-standardized to the 2007 US population. Based on SEARCH, an estimated 36 million Pap tests were performed in 2007 for 91 million US women aged 21-65 years, leading to 2.3 million abnormal Pap tests, 1.5 million punch biopsies, 0.3 million treatments for precancerous lesions, 5 thousand preterm births and over 8 million health problems. Under the Netherlands screening practice, fewer Pap tests (58%), abnormal test results (64%), punch biopsies (75%), treatment procedures (40%), preterm births (60%) and health problems (63%) would have occurred. The SEARCH data did not differ much from other US data for 2007 or from more recent data up to 2013. Thus compared to the less intensive screening practice in the Netherlands, US practice of cervical cancer screening may have resulted in two- to threefold higher harms, while the effects on cervical cancer incidence and mortality are similar. The results are also of high relevance in making recommendations for HPV screening. Systematic collection of harms data is needed for monitoring and for better incorporation of harms in making screening recommendations.

Cervical cancer incidence after normal cytological sample in routine screening using SurePath, ThinPrep, and conventional cytology: population based study

Objective To compare the cumulative incidence of cervical cancer diagnosed within 72 months after a normal screening sample between conventional cytology and liquid based cytology tests SurePath and ThinPrep.Design Retrospective population based cohort study.Setting Nationwide network and registry of histo- and cytopathology in the Netherlands (PALGA), January 2000 to March 2013.Population Women with 5 924 474 normal screening samples (23 833 123 person years).Exposure Use of SurePath or ThinPrep versus conventional cytology as screening test.Main outcome measure 72 month cumulative incidence of invasive cervical cancer after a normal screening sample for each screening test. Cox regression analyses assessed the hazard ratios, adjusted for calendar time, age, screening history, and socioeconomic status and including laboratories as random effects.Results The 72 month cumulative cancer incidence was 58.5 (95% confidence interval 54.6 to 62.7) per 100 000 normal conventional cytology samples, compared with 66.8 (56.7 to 78.7) for ThinPrep and 44.6 (37.8 to 52.6) for SurePath. Compared with conventional cytology, the hazard of invasive cancer was 19% lower (hazard ratio 0.81, 95% confidence interval 0.66 to 0.99) for SurePath, mainly caused by a 27% lower hazard (0.73, 0.57 to 0.93) of a clinically detected cancer. For ThinPrep, the hazard was on average 15% higher (hazard ratio 1.15, 0.95 to 1.38), mainly caused by a 56% higher hazard of a screen detected cancer (1.56, 1.17 to 2.08).Conclusions These findings should provoke reconsideration of the assumed similarity in sensitivity to detect progressive cervical intraepithelial neoplasia between different types of liquid based cytology and conventional cytology.

Public Health Benefits of Routine Human Papillomavirus Vaccination for Adults in the Netherlands: A Mathematical Modeling Study

BACKGROUND

Expanding routine human papillomavirus (HPV) vaccination to adults could be an effective strategy to improve prevention of HPV infection and cervical cancer.

METHODS

We evaluated the following adult vaccination strategies for women only and for both women and men in addition to the current girls-only vaccination program in the Netherlands, using the established STDSIM microsimulation model: one-time mass campaign, vaccination at the first cervical cancer screening visit, vaccination at sexual health clinics, and combinations of these strategies.

RESULTS

The estimated impact of expanding routine vaccination to adult women is modest, with the largest incremental reductions in the incidence of HPV infection occurring when offering vaccination both at the cervical cancer screening visit and during sexually transmitted infection (STI) consultations (about 20% lower after 50 years for both HPV-16 and HPV-18). Adding male vaccination during STI consultations leads to more-substantial incidence reductions: 63% for HPV-16 and 84% for HPV-18. The incremental number needed to vaccinate among women is 5.48, compared with 0.90 for the current vaccination program.

CONCLUSIONS

Offering vaccination to adults, especially at cervical cancer screening visits (for women) and during STI consultations (for both sexes), would substantially reduce HPV incidence and would be an efficient policy option to improve HPV prevention and subsequently avert cervical and possibly male HPV-related cancers.

The potential harms of primary human papillomavirus screening in over-screened women: a microsimulation study

BACKGROUND

It is well acknowledged that HPV testing should not be performed at young age and at short intervals. Cytological screening practices have shown that over-screening, i.e., from a younger age and at shorter intervals than recommended, is hard to avoid. We quantified the consequences of a switch to primary HPV screening for over-screened women, taking into account its higher sensitivity but lower specificity than cytology.

METHODS

The health effects of using the HPV test instead of cytology as the primary screening method were determined with the MISCAN-Cervix model. We varied the age women start screening and the interval between screens. In the sensitivity analyses, we varied the background risk of cervical cancer, the HPV prevalence, the discount rate, the triage strategy after cytology, and the test characteristics of both cytology and the HPV test.

RESULTS

For women screened 5 yearly from age 30, 32 extra deaths per 100,000 simulated women were prevented when switching from primary cytology to primary HPV testing. For annual screening from age 20, such a switch resulted in 6 extra deaths prevented. It was associated with 9,044 more positive primary screens in the former scenario versus 76,480 in the latter. Under all conditions, for women screened annually, switching to HPV screening resulted in a net loss of quality-adjusted life years.

CONCLUSION

For over-screened women, the harms associated with a lower test specificity outweigh the life years gained when switching from primary cytology to primary HPV testing. The extent of over-screening should be considered when deciding on inclusion of primary HPV screening in cervical cancer screening guidelines.

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

Background

Vaccination against the oncogenic human papillomavirus (HPV) types 16 and 18 will reduce the prevalence of these types, thereby also reducing cervical cancer risk in unvaccinated women. This (measurable) herd effect will be limited at first, but is expected to increase over time. At a certain herd immunity level, tailoring screening to vaccination status may no longer be worth the additional effort. Moreover, uniform screening may be the only viable option. We therefore investigated at what level of herd immunity it is cost-effective to also reduce screening intensity in unvaccinated women.

Methods

We used the MISCAN-Cervix model to determine the optimal screening strategy for a pre-vaccination population and for vaccinated women (~80% decreased risk), assuming a willingness-to-pay of €50,000 per quality-adjusted life year gained. We considered HPV testing, cytology testing and co-testing and varied the start age of screening, the screening interval and the number of lifetime screens. We then calculated the incremental cost-effectiveness ratio (ICER) of screening unvaccinated women with the strategy optimized to the pre-vaccination population as compared to with the strategy optimized to vaccinated women, assuming different herd immunity levels.

Results

Primary HPV screening with cytology triage was the optimal strategy, with 8 lifetime screens for the pre-vaccination population and 3 for vaccinated women. The ICER of screening unvaccinated women 8 times instead of 3 was €28,085 in the absence of herd immunity. At around 50% herd immunity, the ICER reached €50,000.

Conclusion

From a herd immunity level of 50% onwards, screening intensity based on the pre-vaccination risk level becomes cost-ineffective for unvaccinated women. Reducing the screening intensity of uniform screening may then be considered.

Beware of Kinked Frontiers: A Systematic Review of the Choice of Comparator Strategies in Cost-Effectiveness Analyses of Human Papillomavirus Testing in Cervical Screening

OBJECTIVES

To systematically review the choice of comparator strategies in cost-effectiveness analyses (CEAs) of human papillomavirus testing in cervical screening.

METHODS

The PubMed, Web of Knowledge, and Scopus databases were searched to identify eligible model-based CEAs of cervical screening programs using human papillomavirus testing. The eligible CEAs were reviewed to investigate what screening strategies were chosen for analysis and how this choice might have influenced estimates of the incremental cost-effectiveness ratio (ICER). Selected examples from the reviewed studies are presented to illustrate how the omission of relevant comparators might influence estimates of screening cost-effectiveness.

RESULTS

The search identified 30 eligible CEAs. The omission of relevant comparator strategies appears likely in 18 studies. The ICER estimates in these cases are probably lower than would be estimated had more comparators been included. Five of the 30 studies restricted relevant comparator strategies to sensitivity analyses or other subanalyses not part of the principal base-case analysis. Such exclusion of relevant strategies from the base-case analysis can result in cost-ineffective strategies being identified as cost-effective.

CONCLUSIONS

Many of the CEAs reviewed appear to include insufficient comparator strategies. In particular, they omit strategies with relatively long screening intervals. Omitting relevant comparators matters particularly if it leads to the underestimation of ICERs for strategies around the cost-effectiveness threshold because these strategies are the most policy relevant from the CEA perspective. Consequently, such CEAs may not be providing the best possible policy guidance and lead to the mistaken adoption of cost-ineffective screening strategies.

Comparing SurePath, ThinPrep, and conventional cytology as primary test method: SurePath is associated with increased CIN II+ detection rates

Purpose

Within the last decade, SurePath and ThinPrep [both liquid-based cytology (LBC) tests] have replaced conventional cytology (CC) as primary test method in cervical cancer screening programs of multiple countries. The aim of our study was to examine the effect in the Dutch screening program.

Methods

All primary smears taken within this program from 2000 to 2011 were analyzed using the nationwide registry of histo- and cytopathology (PALGA) with a follow-up until March 2013. The percentage of smears classified as borderline/mildly dyskaryotic (BMD) and >BMD as well as CIN and cervical cancer detection rates were compared between SurePath and ThinPrep versus CC by logistic regression analyses (adjusted for age, screen region, socioeconomic status, and calendar time).

Results

We included 3,118,685 CC, 1,313,731 SurePath, and 1,584,587 ThinPrep smears. Using SurePath resulted in an increased rate of primary smears classified as >BMD [odds ratio (OR) = 1.12 (95% confidence interval (CI) 1.09–1.16)]. CIN I and II⁺ detection rates increased by 14 % [OR = 1.14 (95% CI 1.08–1.20)] and 8 % [OR = 1.08 (95% CI 1.05–1.12)]. Cervical cancer detection rates were unaffected. Implementing ThinPrep did not result in major alterations of the cytological classification of smears, and it did not affect CIN detection rates. While not significant, cervical cancer detection rates were lower [OR = 0.87 (95% CI 0.75–1.01)].

Conclusions

The impact of replacing CC by LBC as primary test method depends on the type of LBC test used. Only the use of SurePath was associated with increased CIN II⁺ detection, although it simultaneously increased the detection of CIN I.

Exploring the trend of increased cervical intraepithelial neoplasia detection rates in the Netherlands

OBJECTIVE

Over the last decade, cervical intraepithelial neoplasia (CIN) detection has increased in the Netherlands. We investigated the underlying mechanism by quantifying the increase, and analyzing patterns of CIN and cervical cancer detection over time.

METHODS

We observed annual CIN and cervical cancer detection rates (DRs) per 10,000 primary smears within the Dutch screening programme for 2000-2011. Joinpoint analyses were performed to determine changes in time trends, logistic regression analyses to assess the relative risk of calendar time on histological outcomes, adjusted for demographic factors and type of primary cytology test used.

RESULTS

Trends of increased detection occurred for all CIN grades (ie. DRs increased from 17.8 to 36.1, from 21.0 to 35.5, and from 43.4 to 64.6 for CIN I, II, and III from 2003 to 2009). After adjusting for demographic factors, DRs were still 2.11 (95% confidence interval (CI): 1.95, 2.29), 1.79 (95% CI: 1.66, 1.92) and 1.59 (95% CI: 1.50, 1.67) times larger in 2009. When also adjusting for the type of cytology test, DRs were 1.90 (95% CI: 1.62, 2.22), 1.48 (95% CI: 1.22, 1.79) and 1.55 (95% CI: 1.39, 1.73) times larger. No trends in cervical cancer DRs were found.

CONCLUSIONS

The implementation of liquid-based cytology contributed to the CIN increase. If some of these extra detected CIN are regressive this leads to overdiagnosis. Other factors, such as an increased cervical cancer risk, and implementation of imaging-assisted reading, could also have contributed.

The role of acquired immunity in the spread of human papillomavirus (HPV): explorations with a microsimulation model

Background

Knowledge of the natural history of human papillomavirus (HPV), in particular the role of immunity, is crucial in estimating the (cost-) effectiveness of HPV vaccination and cervical cancer screening strategies, because naturally acquired immunity after clearing an infection may already protect part of the risk population against new HPV infections.

Methods

We used STDSIM, an established stochastic microsimulation model, quantified to the Netherlands. We explored different assumptions regarding the natural history of HPV-16 and HPV-18, and estimated the transmission probabilities and durations of acquired immunity necessary to reproduce age-specific prevalence.

Results

A model without acquired immunity cannot reproduce the age-specific patterns of HPV. Also, it is necessary to assume a high degree of individual variation in the duration of infection and acquired immunity. According to the model estimates, on average 20% of women are immune for HPV-16 and 15% for HPV-18. After an HPV-16 infection, 50% are immune for less than 1 year, whereas 20% exceed 30 years. For HPV-18, up to 12% of the individuals are immune for less than 1 year, and about 50% over 30 years. Almost half of all women will never acquire HPV-16 or HPV-18.

Conclusions

Acquired immunity likely plays a major role in HPV epidemiology, but its duration shows substantial variation. Combined with the lifetime risk, this explains to a large extent why many women will never develop cervical cancer.

Offering Self-Sampling to Non-Attendees of Organized Primary HPV Screening: When Do Harms Outweigh the Benefits?

BACKGROUND

Human papillomavirus (HPV) self-sampling might be a promising tool to increase effectiveness of primary HPV screening programs when offered to non-attendees. However, effectiveness could decrease if regular attendees "switch" to self-sampling, because self-sampling test characteristics may be inferior. We examined under which conditions the harms would outweigh the benefits.

METHODS

The MISCAN-cervix model was used to estimate quality-adjusted life years (QALY) gained and costs of offering HPV self-sampling to non-attendees. We varied the relative CIN2(+) sensitivity and specificity (self-sampling vs. regular sampling), extra attendance, risk of extra attendees, and the switching percentage.

RESULTS

Without switching, offering self-sampling is (cost-)effective under every studied condition. If the attendance due to self-sampling increases by ≥6 percentage points, higher primary background risk women (unscreened women who will never attend regular screening) attend and the relative CIN2(+) sensitivity and specificity are ≥0.95; it is (cost-)effective to offer self-sampling to non-attendees, even if all regular attendees switch. If the relative sensitivity decreases to 0.90 combined with either a 3 percentage points extra attendance or the absence of higher primary background risk women, QALYs are lost when more than 30% to 20% of the regular attendees switch.

CONCLUSIONS

Offering self-sampling will gain health effects if the relative CIN2(+) sensitivity is ≥0.95, unscreened attendees are recruited, and the total attendance increases by ≥6 percentage points. Otherwise, switching of regular attendees may decrease the total effectiveness of the program.

IMPACT

Self-sampling needs to be implemented with great care and advantages of office-based sampling need to be emphasized to prevent switching.

How many cervical cancer cases can potentially be prevented using a more sensitive screening test at young age?

The human papilloma virus (HPV) DNA test has higher sensitivity than cytology for cervical cancer screening. Therefore, cervical cancer cases that are missed by cytology could potentially be identified if we use primary HPV testing. Studies showed that HPV screening is the preferred primary test at age 35 and over. Given the high prevalence of harmless HPV infections, the use of HPV testing at younger age is less obvious. The number of cancers in young age is often mentioned to indicate the possible benefits of a more sensitive test. We actually estimated the proportion of those cases that is potentially preventable in The Netherlands by the use of a more sensitive screen-test at the first screening age 30, given that the more sensitive test is used at age 35 and over. We analysed the screening history of women diagnosed with cervical cancer in the period 2004 to March 2009, using data from the Dutch National Pathology Registry. Only 15-30% (two to four cases per 100,000 women) of the cases was preceded by negative cytology under age 35 and therefore could have been prevented by a more sensitive test at age 30. The lower the screening coverage and the shorter the screening interval in those screened at young age, the smaller the gain of a more sensitive test. So, as long as the current screening pattern is not changed, the majority of the cervical cancer cases at young age would still occur even when applying a more sensitive test at the younger ages.

Increasing girls' knowledge about human papillomavirus vaccination with a pre-test and a national leaflet: a quasi-experimental study

Background

Adolescent girls are at an age to be involved in the decision about HPV vaccination uptake and therefore need adequate information about the vaccination. This study assesses to what extent reading an official information leaflet about HPV contributes to girls’ knowledge levels, and to what extent an increase in knowledge is boosted by a pre-test measurement.

Methods

Participants (girls aged 11–14 years) were systematically allocated to group A that completed a pre-test measurement (12 true/false statements) or to group B that did not complete it. Subsequently, both groups read the HPV leaflet and completed the post-test measurement.

Results

The response rate was 237/287 (83%). Pre-test scores in group A (M = 3.6, SD = 1.81, p < 0.001) were lower than post-test mean knowledge scores (0–10) in group B (M = 4.6, SD = 2.05). Post-test knowledge scores in group A were higher than those in group B [6.2 (SD = 2.06) versus 4.6 (SD = 2.05), p < 0.001]. In the post-test measurement, about a third of both groups knew that vaccinations do not give 100% protection against cervical cancer and that the duration of protection is unknown.

Conclusions

Reading the information leaflet had a positive effect on knowledge, even more so when boosted by a pre-test measurement. However, knowledge on the degree and duration of protection against cervical cancer remained limited. Focusing girls’ attention on important aspects before they start reading the leaflet (e.g. by including a quiz on the first page) may serve to raise their awareness of these aspects.

Liquid-based cervical cytology using ThinPrep technology: weighing the pros and cons in a cost-effectiveness analysis

PURPOSE

Cervical cancer screening with liquid-based cytology (LBC) has been developed as an alternative to the conventional Papanicolaou (CP) smear. Cost-effectiveness is one of the issues when evaluating LBC. Based on the results of a Dutch randomised controlled trial, we conducted cost-effectiveness threshold analyses to investigate under what circumstances manually screened ThinPrep LBC is cost-effective for screening.

METHODS

The MISCAN-Cervix microsimulation model and data from the Dutch NETHCON trial (including 89,784 women) were used to estimate the costs and (quality-adjusted) life years ((QA)LYs) gained for EU screening schedules, varying cost-effectiveness threshold values. Screening strategies were primary cytological screening with LBC or CP, and triage with human papillomavirus (HPV) testing.

RESULTS

Threshold analyses showed that screening with LBC as a primary test can be cost-effective if LBC is less than <euro>3.2 more costly per test than CP, if the sensitivity of LBC is at least 3-5 % points higher than CP, if the quality of life for women in triage follow-up is only 0.39, or if the rate of inadequate CP smears is at least 16.2 %.

CONCLUSIONS

Regarding test characteristics and costs of LBC and CP, only under certain conditions will a change from CP to manually screened ThinPrep LBC be cost-effective. If none of these conditions are met, implementation of manually screened ThinPrep LBC seems warranted only if there are advantages other than cost-effectiveness. Further research is needed to establish whether other LBC systems will be more favorable with regard to cost-effectiveness.

Primary screening for human papillomavirus compared with cytology screening for cervical cancer in European settings: cost effectiveness analysis based on a Dutch microsimulation model

OBJECTIVES

To investigate, using a Dutch model, whether and under what variables framed for other European countries screening for human papillomavirus (HPV) is preferred over cytology screening for cervical cancer, and to calculate the preferred number of examinations over a woman's lifetime.

DESIGN

Cost effectiveness analysis based on a Dutch simulation model. Base case analyses investigated the cost effectiveness of more than 1500 different screening policies using the microsimulation model. Subsequently, the policies were compared for five different scenarios that represent different possible scenarios (risk of cervical cancer, previous screening, quality associated test characteristics, costs of testing, and prevalence of HPV).

SETTING

Various European countries.

POPULATION

Unvaccinated women born between 1939 and 1992.

MAIN OUTCOME MEASURES

Optimal screening strategy in terms of incremental cost effectiveness ratios (costs per quality adjusted life years gained) compared with different cost effectiveness thresholds, for two levels of sensitivity and costs of the HPV test.

RESULTS

Primary HPV screening was the preferred primary test over the age of 30 in many considered scenarios. Primary cytology screening was preferred only in scenarios with low costs of cytology and in scenarios with a high prevalence of HPV in combination with high costs of HPV testing.

CONCLUSIONS

Most European countries should consider switching from primary cytology to HPV screening for cervical cancer. HPV screening must, however, only be implemented in situations where screening is well controlled.

Practical implications of differential discounting in cost-effectiveness analyses with varying numbers of cohorts

OBJECTIVE

To call attention to the influence of the number of birth-cohorts used in cost-effectiveness analysis (CEA) models on incremental cost-effectiveness ratios (ICERs) under differential discounting.

METHODS

The consequences of increasing the number of birth-cohorts are demonstrated using a CEA of cervical cancer prevention as an example. The cost-effectiveness of vaccinating 12-year-old girls against the human papillomavirus is estimated with the MISCAN microsimulation screening analysis model for 1, 10, 20, and 30 birth-cohorts. Costs and health effects are discounted with equal rates of 4% and alternatively with differential rates of 4% and 1.5% respectively. The effects of increasing the number of cohorts are shown by comparing the ICERs under equal and differential discounting.

RESULTS

The ICER decreases as the number of cohorts increases under differential discounting, but not under equal discounting.

CONCLUSIONS

The variation of ICERs with the number of cohorts under differential discounting prompts questions regarding the appropriate specification of CEA models and interpretation of their results. In particular, it raises concerns that arbitrary variation in study specification leads to arbitrary variation in results. Such variations could lead to erroneous policy decisions. These findings are relevant to CEA guidance authorities, CEA practitioners, and decision makers. Our results do not imply a problem with differential discounting per se, yet they highlight the need for practical guidance for its use.

Trends in cervical cancer in the Netherlands until 2007: has the bottom been reached?

We explored trends in incidence and mortality of cervical cancer by age, stage and morphology, and linked the observed trends to screening activities. Data was retrieved from the Netherlands Cancer Registry during 1989-2007 (incidence) and Statistics Netherlands during 1970-2007 (mortality). Trends were evaluated by calculating the estimated annual percentage change (EAPC). Joinpoint regression analysis was used to detect changes in trends. Cervical intraepithelial neoplasia (CIN) detection rates were calculated by data from "the nationwide network and registry of histo- and cytopathology" during 1990-2006. Total age-adjusted incidence rate (European standardized rate (ESR)) was 7.9 per 100,000 woman years in 2007. During 1989-1998, incidence rates decreased with an EAPC of -1.3% (95% confidence interval (CI) -2.2 to -0.3), during 1998-2001 with -6.7% (95% CI: -16.4 to 4.1), and increased during 2001-2007 with 2.3% (95% CI: 0.4 to 4.2). Total mortality ESR was 1.9 per 100,000 woman years in 2007. Mortality rates decreased during 1970-1994 annually with -4.1% (95% CI: -4.6% to -3.7%), and with -2.6% (95% CI: -3.8% to -1.5%) during 1994-2007. The observed trend in total incidence is similar to the trend in squamous cell carcinomas in age group 35-54 years, suggesting that the observed trends are likely to be associated to changes in the screening program. This is supported by the trend in CINIII detection rates. In conclusion, incidence and mortality overall decreased and leveled off. On top of that there was an extra decrease that was compensated by a following recent increase in incidence, probably resulting from reorganization of the Dutch screening program.

[Unequal discounting of health care costs and effects causes confusion]

Discounting is a widely accepted practice in cost-effectiveness analysis to weigh future costs and effects for their timing. In 2006, the Dutch Health Care Insurance Board revised its recommended rates for discounting. They recommended differential discounting of costs and effects, whereby effects are discounted at a lower rate relative to the costs. The question is whether this guideline is to be generally used for decision-making in the Netherlands. We show how the use of unequal discount rates leads to confusing cost-effectiveness results and why further implementation guidelines are essential.

Childhood social class and cancer incidence: results of the globe study

Despite increased recognition of the importance of investigating socio-economic inequalities in health from a life course perspective, little is known about the influence of childhood socio-economic position (SEP) on cancer incidence. The authors studied the association between father's occupation and adult cancer incidence by linking information from the longitudinal GLOBE study with the regional population-based Eindhoven Cancer Registry (the Netherlands) over a period of 14 years. In 1991, 18,973 participants (response rate 70.1%) of this study responded to a postal questionnaire, including questions on SEP in youth and adulthood. Respondents above the age of 24 were included (N=12,978). Cox regression was used to calculate hazard ratios (HR) for all cancers as well as for the five most frequently occurring cancers by respondent's educational level or occupational class, and by father's occupational class (adjusted for respondent's education and occupation). Respondents with a low educational level showed an increased risk of all cancers, lung and breast cancer (in women). Respondents with a low adult occupational level showed an increased risk of lung cancer and a reduced risk of basal cell carcinoma. After adjustment for adult education and occupation, respondents whose father was in a lower occupational class showed an increased risk of colorectal cancer as compared to those with a father in the highest social class. In contrast, respondents whose father was in a lower occupational class, showed a decreased risk of basal cell carcinoma as compared to those with a father in the highest occupational class. The association between childhood SEP and cancer incidence is less consistent than the association between adult SEP and cancer incidence, but may exist for colorectal cancer and basal cell carcinoma.

Risk factors for otitis media: an international perspective

BACKGROUND

Opinions about otitis media (OM) as an illness and about the need for antibiotic or surgical treatment vary internationally. It is not known how this is to be explained, whether by cultural differences or by other factors, such as variation in environmental risk factors for OM.

OBJECTIVES

To report on variation in environmental risk factors for OM across Western countries, and on the organisation of health care in these countries.

METHODS

Main environmental risk factors for OM were identified by searching Pubmed. Data on the distribution of these risk factors and the organisation of health care across countries were obtained from the OECD and WHO websites.

RESULTS

Main risk factors for OM were day-care, number of siblings, smoking, breastfeeding, birth weight, socio-economic status (SES) and air pollution. Data were available for several European countries, the United State, Canada and Australia. Large international differences were found regarding the proportion of children attending day-care (Sweden 75% versus Italy 6%) and being breastfed at age 6 months (Norway 80% versus Poland 6%), and the rate of female smokers (Germany, France and Norway 30-40% versus Portugal <10%).

CONCLUSION

It appears that differences in risk factor exposure between populations are often overshadowed by other culturally or demographically significant factors. Attempts to discern these factors within populations and between countries may be important in the management of OM and warrants further study.