Changing inequalities in cervical cancer: modeling the impact of vaccine uptake, vaccine herd effects, and cervical cancer screening in the post-vaccination era

Population-level impact of switching to 1-dose human papillomavirus vaccination in high-income countries: examining uncertainties using mathematical modeling

BACKGROUND

A concern in high-income countries is that switching to 1-dose human papillomavirus (HPV) vaccination could cause a rebound in HPV infection and cervical cancer if 1-dose efficacy or duration were inferior to 2 doses. Using mathematical modeling and up-to-date trial-based data, we projected the population-level effectiveness of switching from 2-dose to 1-dose vaccination under different vaccine efficacy and duration assumptions in high-income countries.

METHODS

We used HPV-ADVISE (Agent-based Dynamic model for VaccInation and Screening Evaluation), a transmission-dynamic model of HPV infection and cervical cancer, varying key model assumptions to identify those with the greatest impact on projections of HPV-16 and cervical cancer incidence over time: 1) 1-dose vaccine efficacy and vaccine duration, 2) mechanisms of vaccine efficacy and duration over time, 3) midadult (>30 years of age) sexual behavior, 4) progression to cervical cancer among midadults, and 5) vaccination coverage and programs.

RESULTS

In high-income countries, 1-dose vaccination would cause no appreciable rebound in HPV-16 infection, except for a limited rebound under the most pessimistic assumptions of vaccine duration (average, 25 years), because 1) the switch would occur when HPV prevalence is low because of high 2-dose vaccination coverage and 2) individuals would be protected during their peak ages of sexual activity (<35 to 40 years of age). Our model projects a more limited rebound in cervical cancer because of a shift to older age at infection, resulting in fewer life-years left to potentially develop cancer. Projections were robust when varying key model assumptions.

CONCLUSIONS

High protection during peak ages of sexual activity in high-income countries would likely mitigate any potential rebounds in HPV infection and cervical cancer under the most pessimistic assumptions of 1-dose efficacy and duration.

A systematic review of the cost-effectiveness of interventions to increase cervical cancer screening among underserved women in Europe

BACKGROUND

This study aimed to conduct a systematic review of the cost-effectiveness studies of interventions to increase cervical cancer screening uptake rates in underserved women in Europe.

METHODS

A search of Embase, Medline, Global Health, PsychINFO, and NHS Economic Evaluation Database was conducted for studies published between January 2000 and September 2022. Studies were eligible if they analysed the cost-effectiveness of any interventions to improve participation in cervical cancer screening among underserved women of any age eligible to participate in cervical cancer screening in European countries, in any language. Study characteristics and cost-effectiveness results were summarised. Study quality was assessed using the Drummond Checklist, and methodological choices were further compared.

RESULTS

The searches yielded 962 unique studies, with 17 of these (from twelve European countries) meeting the eligibility criteria for data extraction. All studies focused on underscreened women as an overarching group, with no identified studies focusing on specific subgroups of underserved women. Generally, self-HPV testing and reminder interventions were shown to be cost-effective to increase the uptake rates. There was also research showing that addressing access issues and adopting different screening modalities could be economically attractive in some settings, but the current evidence is insufficient due to the limited number of studies.

CONCLUSION

This systematic review has revealed a gap in the literature on the cost-effectiveness of interventions to improve uptake rates of cervical cancer screening through tailored provision for specific groups of underserved women.

Post Treatment Sexual Function and Quality of Life of Patients Affected by Cervical Cancer: A Systematic Review

Introduction: The aim of this study is to analyze the available scientific evidence regarding the quality of life (QoL) and sexual function (SF) in patients affected by cervical cancer (CC) after surgical and adjuvant treatments. Materials and Methods: Preliminary research was conducted via electronic database (MEDLINE, PubMed and Cochrane Library) with the use of a combination of the following keywords: SF, QoL, and CC. The principal findings considered in the present review were the study design, the number of patients included in each study, the information about the malignancy (histology and stage of disease), the questionnaires administered, and the principal findings concerning SF and QoL. Results: All studies were published between 2003–2022. The studies selected consisted of one randomized control study, seven observational studies (three prospective series), and nine case control studies. The scores used were focused on SF, QOL, fatigue, and psychological aspects. All studies reported a decreased SF and QOL. The most developed questionnaires were the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ-C30), the Female Sexual Function Index (FSFI), the Hospital Anxiety and Depression scale (HADS), and the Female Sexual Distress Scale (FSDS). Discussion: All studies reported a decreased SF and QOL. In addition to the perception of body image, several factors coexist in influencing the outcomes such as the physical, hormonal, psychological. Conclusions: Sexual dysfunction after CC treatment has a multifactorial aetiology which negatively affects the quality of life. For these reasons, it is important to follow and support patients with a multidisciplinary team (doctors, nurses, psychologists, dieticians) before and after therapy. This type of tailored therapeutic approach should become a standard. Women should be informed about possible vaginal changes and menopausal symptoms after surgery and on the positive effects of psychological therapy.

Differences in school factors associated with adolescent HPV vaccination initiation and completion coverage in three Australian states

BACKGROUND

Schools are the primary setting for the delivery of adolescent HPV vaccination in Australia. Although this strategy has achieved generally high vaccination coverage, gaps persist for reasons that are mostly unknown. This study sought to identify school-level correlates of low vaccination course initiation and completion in New South Wales, Tasmania, and Western Australia to inform initiatives to increase uptake.

METHODS

Initiation was defined as the number of first doses given in a school in 2016 divided by vaccine-eligible student enrolments. Completion was the number of third doses given in a school in 2015-2016 divided by the number of first doses. Low initiation and completion were defined as coverage ≤ 25thpercentile of all reporting schools. We investigated correlations between covariates using Spearman's rank correlation coefficients. Due to multicollinearity, we used univariable logistic regression to investigate associations between school characteristics and low coverage.

RESULTS

Median initiation was 84.7% (IQR: 75.0%-90.4%) across 1,286 schools and median completion was 93.8% (IQR: 86.0%-97.3%) across 1,295 schools. There were strong correlations between a number of school characteristics, particularly higher Indigenous student enrolments and lower attendance, increasing remoteness, higher postcode socioeconomic disadvantage, and smaller school size. Characteristics most strongly associated with low initiation in univariate analyses were small school size, location in Tasmania, and schools catering for special educational needs. Low completion was most strongly associated with schools in Tasmania and Western Australia, remote location, small size, high proportion of Indigenous student enrolments, and low attendance rates.

CONCLUSION

This study provides indicative evidence that characteristics of schools and school populations are associated with the likelihood of low initiation and completion of the HPV vaccination course. The findings will guide further research and help target initiatives to improve vaccination uptake in schools with profiles associated with lower coverage.

Impact and cost-effectiveness of strategies to accelerate cervical cancer elimination: A model-based analysis

Following the global call for action by the World Health Organization to eliminate cervical cancer (CC), we evaluated how each CC policy decision in Norway influenced the timing of CC elimination, and whether introducing nonavalent human papillomavirus (HPV) vaccine would accelerate elimination timing and be cost-effective. We used a multi-modeling approach that captured HPV transmission and cervical carcinogenesis to estimate the CC incidence associated with six past and future CC prevention policy decisions compared with a pre-vaccination scenario involving 3-yearly cytology-based screening. Scenarios examined the introduction of routine HPV vaccination of 12-year-old girls with quadrivalent vaccine in 2009, a temporary catch-up program for females aged up to 26 years in 2016-2018 with bivalent vaccine, the universal switch to bivalent vaccine in 2017, expansion to include 12-year-old boys in 2018, the switch from cytology- to HPV-based screening for women aged 34-69 in 2020, and the potential switch to nonavalent vaccine in 2021. Introducing routine female vaccination in 2009 enabled elimination to be achieved by 2056 and prevented 17,300 cases. Cumulatively, subsequent policy decisions accelerated elimination to 2039. According to our modeling assumptions, switching to the nonavalent vaccine would not be considered 'good value for money' at relevant cost-effectiveness thresholds in Norway unless the incremental cost was $19 per dose or less (range: $17-24) compared to the bivalent vaccine. CC control policies implemented over the last decade in Norway may have accelerated the timeframe to elimination by more than 17 years and prevented over 23,800 cases by 2110.

Moving toward the elimination of cervical cancer: modelling the health and economic benefits of increasing uptake of human papillomavirus vaccines

Background

The human papillomavirus (hpv) is a common sexually transmitted infection and a primary cause of cervical cancer. The Government of Canada has set a target of reaching 90% hpv vaccine coverage among adolescents by 2025. Here, we examine hpv vaccine uptake in school-based immunization programs across Canada and explore how achieving the 90% target could affect the future incidence of cervical cancer, mortality, and health system expenditures in a cohort of Canadian women.

Methods

Data for hpv vaccine uptake in the most recent reported school year available in each jurisdiction were provided in 2017 by jurisdictional school-based immunization programs and were used to estimate a national weighted average of 67%. The OncoSim microsimulation model (version 2.5) was used to compare 3 different levels of hpv vaccine uptake (0%, 67%, 90%) on health and economic outcomes for a hypothetical cohort of all 5- to 10-year-old girls in Canada in 2015.

Results

Vaccine uptake for girls in school-based programs varied from 55.0% to 92.0% in the jurisdictions reviewed. The OncoSim model projects that increasing uptake to 90% from 67% would result in a 23% reduction in cervical cancer incidence rates (to 3.1 cases from 4.0 cases per 100,000, averaged across the lifetime of the cohort) and a 23% decline in the average annual mortality rate (to 1.0 deaths from 1.3 deaths per 100,000). Finally, the model projects that the health system will incur a cost of $9 million (1% increase) during the lifetime of the cohort if uptake is increased to 90% from 67%. Costs are discounted (1.5%) and expressed in 2016 Canadian dollars. Costs reflect the payer perspective.

Conclusions

Our model shows that increasing hpv vaccine uptake to 90% from current levels for girls in school-based immunization programs could result in substantial reductions in the future incidence and mortality rates for cervical cancer in Canada.

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.

Understanding the cervical screening behaviour of Chinese women: The role of health care system and health professions

BACKGROUND

In China, cervical cancer cases are increasing, making an impact on the worldwide burden of cervical cancer. Despite the initiatives undertaken by the Chinese government, the current coverage of cervical screening in China remains suboptimal. There is an urgent need to identify the facilitators and barriers associated with the uptake of cervical cancer screening among the Chinese population.

PURPOSE

The study aimed to explore the experiences and perceptions of cervical cancer screening of mainland Chinese women in relation to their screening behaviour, particularly in the aspects of health care system and health profession roles.

METHODS

A qualitative research was conducted using semi-structured interviews. A total of 27 Chinese women aged 25 to 50 (both screened and non-screened women) completed the interviews. The analysis of the interview data was undertaken inductively using latent content analysis.

DISCUSSION AND CONCLUSION

Results showed that organised health examination programmes provide a good basis for integrating cervical screening into broader checks on the health of women, and utilising different networks of social support facilitate the utilisation of the screening service. However, education on cervical cancer and screening must be made more generally available. More importantly, there is a need for a more participatory and empowering exchange in the encounter between health professions and these women. Appropriate training program is strongly recommended for health professions about communicate skills with patients. Future work should focus on identifying strategies to overcome the barriers to cervical screening related to health care system and medical professions among this population.

Effect of HPV vaccination and cervical cancer screening in England by ethnicity: a modelling study

BACKGROUND

Health equality is increasingly being considered alongside overall health gain when assessing public health interventions. However, the trade-off between the direct effects of vaccination and herd immunity could lead to unintuitive consequences for the distribution of disease burden within a population. We used a transmission dynamic model of human papillomavirus (HPV) to investigate the effect of ethnic disparities in vaccine and cervical screening uptake on inequality in disease incidence in England.

METHODS

We developed an individual-based model of HPV transmission and disease, parameterising it with the latest data for sexual behaviour (from National Survey of Sexual Attitudes and Lifestyles [Natsal-3]) and vaccine and screening uptake by ethnicity (from Public Health England [PHE]) and fitting it to data for HPV prevalence (from ARTISTIC, PHE, Natsal-3) and HPV-related disease incidence (from National Cancer Registry [ONS]). The outcome of interest was the age-adjusted incidence of HPV-related cancer (both cervical and non-cervical) in all women in England in view of differences and changes in vaccination and screening uptake by ethnicity in England, over time. We also studied three potential public health interventions aimed at reducing inequality in HPV-related disease incidence: increasing uptake in black and Asian females to match that in whites for vaccination; cervical screening in women who turn 25 in 2018 or later; and cervical screening in all ages.

FINDINGS

In the pre-vaccination era, before 2008, women from ethnic minorities in England reported a disproportionate share of cervical disease. Our model suggests that Asian women were 1·7 times (95% credibility interval [CI] 1·1-2·7) more likely to be diagnosed with cervical cancer than white women (22·8 vs 13·4 cases per 100 000 women). Because HPV vaccination uptake is lower in ethnic minorities, we predict an initial widening of this gap, with cervical cancer incidence in Asian women up to 2·5 times higher (95% CI 1·3-4·8) than in white women 20 years after vaccine introduction (corresponding to an additional 10·8 [95% CI 10·1-11·5] cases every year). In time, we predict that herd immunity benefits will diffuse from the larger white sub-population and the disparity will narrow. Increased cervical screening uptake in vaccinated women from ethnic minorities would lead to rapid improvement in equality with parity in incidence after 20 years of HPV vaccination.

INTERPRETATION

Our study suggests that the introduction of HPV vaccination in England will initially widen a pre-existing disparity in the incidence of HPV-related cancer by ethnicity, partly due to herd immunity disproportionately benefiting subgroups with high vaccination rates. Although in time this induced disparity will narrow, increasing cervical screening uptake in girls from ethnic minorities should be encouraged to eliminate the inequality in cervical cancer incidence in the medium term. We recommend that dynamic effects should be considered when estimating the effect of public health programmes on equality.

FUNDING

Cancer Research UK.

National assessment of HPV and Pap tests: Changes in cervical cancer screening, National Health Interview Survey

BACKGROUND

Major organizations recommend cytology screening (Pap test) every 3years for women aged 21-65; women aged 30 to 65 have the option of adding the HPV test (co-test) every 5years. We examined national percentages of cervical cancer screening, and we examined use of co-testing as an option for screening.

METHODS

We used 2015 U.S. National Health Interview Survey (NHIS) data to examine recent cervical cancer screening (Pap test within 3years among women aged 21-65 without a hysterectomy; N=10,596) and co-testing (N=9,125). We also conducted a multivariable analysis to determine odds of having had a Pap test or co-test by demographic variables. To evaluate changes in screening over time, we examined Pap testing during the years 2000, 2005, 2008, 2010, 2013 and 2015. Analysis completed in Atlanta, GA during 2016.

RESULTS

Overall, 81.1% of eligible women reported having a Pap test within 3years; percentages declined over time among all age groups. An estimated 14 million women aged 21-65 had not been screened within the past 3years. Recent immigrants to the United States, women without insurance, and women without a usual source of healthcare had lower odds of being up to date with screening. About 1/3 of women up to date on Pap testing reported having a co-test with their most recent Pap test.

CONCLUSIONS

Declines in screening among women aged 21-65 are cause for concern. More research is needed on co-testing practices. Provider and patient education efforts may be needed to clarify recommended use of HPV tests.

An empirical study of the 'underscreened' in organised cervical screening: experts focus on increasing opportunity as a way of reducing differences in screening rates

BACKGROUND

Cervical cancer disproportionately burdens disadvantaged women. Organised cervical screening aims to make cancer prevention available to all women in a population, yet screening uptake and cancer incidence and mortality are strongly correlated with socioeconomic status (SES). Reaching underscreened populations is a stated priority in many screening programs, usually with an emphasis on something like 'equity'. Equity is a poorly defined and understood concept. We aimed to explain experts' perspectives on how cervical screening programs might justifiably respond to 'the underscreened'.

METHODS

This paper reports on a grounded theory study of cervical screening experts involved in program organisation. Participants were 23 experts from several countries and a range of backgrounds: gynecology; epidemiology; public health; pathology; general practice; policy making. Data were gathered via semi-structured interview and concepts developed through transcript coding and memo writing.

RESULTS

Most experts expressed an intuitive commitment to reducing systematic differences in screening participation or cancer outcomes. They took three different implicit positions, however, on what made organised programs justifiable with respect to underscreened populations. These were: 1) accepting that population screening is likely to miss certain disenfranchised groups for practical and cultural reasons, and focusing on maximising mainstream reach; 2) identifying and removing barriers to screening; and 3) providing parallel tailored screening services that attended to different cultural needs. Positions tended to fall along country of practice lines.

CONCLUSIONS

Experts emphasised the provision of opportunity for underscreened populations to take up screening. A focus on opportunity appeared to rely on tacit premises not supported by evidence: that provision of meaningful opportunity leads to increased uptake, and that increased uptake of an initial screening test by disadvantaged populations would decrease cervical cancer incidence and mortality. There was little attention to anything other than the point of testing, or the difficulties disadvantaged women can have in accessing follow up care. The different approaches to 'improving equity' taken by participants are differently justified, and differently justifiable, but none attend directly to the broader conditions of disadvantage.