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Breast cancer screening, community champion, health inequalities, screening uptake, behaviour change
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Salman M, Egeli A, Humphrey A et al. Protocol of a Community Champion led breast cancer screening intervention for underserved groups [version 1; peer review: awaiting peer review]. NIHR Open Res 2026, 6:202 (https://doi.org/10.3310/nihropenres.14454.1)
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Study Protocol
Protocol of a Community Champion led breast cancer screening intervention for underserved groups
[version 1; peer review: awaiting peer review]
PUBLISHED 10 Nov 2026
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Abstract
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Corresponding author:
Maira Salman
Competing interests:
No competing interests were disclosed.
Grant information:
This study is funded by the National Institute for Health and Care Research (NIHR) Public Health Research (PHR) Programme (Reference Number NIHR164908). The views expressed are those of the authors and not necessarily those of the NIHR or the Department of Health and Social Care.
The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Copyright:
© 2026 Salman M et al.
This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
How to cite: Salman M, Egeli A, Humphrey A et al. Protocol of a Community Champion led breast cancer screening intervention for underserved groups [version 1; peer review: awaiting peer review]. NIHR Open Res 2026, 6:202 (https://doi.org/10.3310/nihropenres.14454.1)
First published: 10 Nov 2026, 6:202 (https://doi.org/10.3310/nihropenres.14454.1)
Latest published: 10 Nov 2026, 6:202 (https://doi.org/10.3310/nihropenres.14454.1)
The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
1. Introduction
The early detection of cancer is a cornerstone of public health policy in the United Kingdom (UK). The NHS Long Term Plan1 set an ambitious target that, by 2028, 75% of cancers should be diagnosed at stage I or II, recognising that earlier diagnosis is strongly associated with improved survival outcomes.2 Cancer screening is a key way to achieve this aim, with international consensus that population-based screening programmes are effective in reducing cancer-related mortality.3–6
Breast cancer is the most common cancer among women in the UK, with one in seven women affected during their lifetime.7 Although survival rates have improved in recent decades, prognosis remains highly dependent on stage at diagnosis. Five-year survival exceeds 98% for women diagnosed at stage I, and 89.5% for those at stage II, but decreases to 72.2% at stage III and 26.6% at stage IV.8 The NHS Breast Screening Programme invites women aged 50–70 for a mammogram every three years, and is estimated to save approximately 1,300 lives annually by detecting cancers at earlier stages.9
Following steep declines in national breast cancer screening (BCS) uptake during the Covid-19 pandemic, uptake recovered to the NHS’s 70% target in 2023–24. However, regional coverage remains uneven. London reported the lowest uptake rate in England at 61.6% in 2024, compared with 73.3% in the South East.10 Socio-demographic and socio-economic inequalities in BCS uptake are well documented, spanning both area-level deprivation and ethnicity.11–13 Uptake in the most deprived areas of London (people living in the most deprived Indices of Multiple Deprivation [IMD]14 quintiles) is 56% compared to 66 and 67% in people living in the most affluent two quintiles, an association that remains significant after adjusting for age, geographic screening service area, and ethnicity (adjusted OR = 0.95, P < 0.001).12 Ethnic disparities are also pronounced: in London, adjusted screening uptake ranged from 67% among White British women to 43% among Bangladeshi women and 49% among Black African women.11 These inequities contribute to poorer outcomes: five-year survival for breast cancer in England is 88.4% among women in the least deprived areas compared with 82.1% among those in the most deprived areas (2016–2020).7 These trends raise concerns not only about missed opportunities for early detection but also the persistence of health inequalities leading to delayed diagnosis and poorer outcomes. Addressing inequalities in screening uptake is therefore a critical priority to reduce avoidable mortality and to improve equity in cancer outcomes.
Policy and strategy documents have highlighted the urgency of this challenge, with national strategies prioritising equitable access to screening services,15 resulting in an objective to increase uptake in underserved groups. A recent review has recommended greater attention to identifying specific underserved populations, including designing trials with sufficient power to assess subgroup effects.16
A 2018 mapping exercise by the London Cancer Screening Improvement Board found there were over 100 interventions were being delivered across London to improve cancer screening uptake, yet none of those specifically targeting breast cancer screening and funded by local authorities were classified as evidence-based.17 Local and regional advisory groups have recommended community engagement as a strategy to improve screening uptake. The Independent Review of Adult Screening Programmes in England specifically recommended encouraging links with faith and community leaders as part of a wider set of evidence-based initiatives to increase uptake, alongside text reminders, social media campaigns, and sharing best practice for physical and learning disabilities.18 Similarly, the National Cancer Plan’s equality impact assessment highlighted the need to work through community organisations, including faith groups, to reduce inequalities in cancer screening uptake.19 However, rigorous evaluation of community engagement models remains scarce.20 Systematic evidence underscores the inconsistency of existing approaches: a recent systematic review of patient-facing interventions designed to increase BCS attendance found that only half demonstrated effectiveness, and only a narrow range of techniques have been investigated to date, with prompts as the most commonly used technique.21 Strategies focused on enhancing self-belief, leveraging social support, or embedding observational learning achieved higher levels of attendance than those focused solely on outlining the consequences of non-attendance. Interventions that employed a credible source were also more successful, suggesting that the messenger may be as important as the message in shaping behaviour.21
Our prior work has explored these principles in practice. We developed and evaluated an animated BCS video intervention, co-designed with women and disseminated via SMS reminders as part of a three-armed randomised controlled trial.22 Although feedback on the intervention was positive, uptake did not increase, with fewer than 6% of women clicking on the link to the video.23,24 Subsequent qualitative work indicated that women expressed a preference for receiving information from trusted individuals within their community rather than through anonymous digital channels (unpublished). These findings highlight both the limitations of digital-only approaches and the potential advantages of interventions that incorporate trusted community figures.
The community champion model represents one such approach. Community champions are individuals embedded within local populations, who use their existing trust with individuals and networks to promote health interventions in culturally sensitive and contextually appropriate ways.25 This model has been applied across cancer awareness and screening contexts, including a UK feasibility study involving training community champions to deliver cancer symptom awareness messages in a socioeconomically deprived area.25 Separately a US peer-to-peer BCS programme, delivered by and targeting women who identified as having African heritage, found that the pattern of screening differed significantly between women of African heritage and other groups over time (p = 0.022); specifically, a higher, though not statistically significant, proportion of women of African heritage screened within areas of champion activity during the intervention period (X2 = 3.0845, p = 0.079).26 By bridging the gap between formal health services and community members, champions may help address barriers of mistrust, language, and cultural relevance that often undermine engagement with traditional screening services.26
To date, no UK studies have rigorously evaluated the effectiveness of community champion-led interventions specifically to increase breast cancer screening uptake. Related UK work has demonstrated the promise of peer-led, and co-produced approaches in other cancer contexts: a peer-led, asset-based intervention improved prostate cancer knowledge and testing intention among Black men in North-East England and Scotland,27 while a peer-led, faith-based intervention co-designed with Muslim women significantly increased intention to engage in breast, cervical, and colorectal screening.28 However, both studies were feasibility studies with relatively small samples, and neither specifically evaluated attendance outcomes. Collectively, these studies show promise for this method of intervention, whilst underscoring the need for a rigorously evaluated, UK-specific community champion intervention targeting BCS uptake directly.
The present study seeks to address this gap. Our proposed intervention combines co-designed resources, including an animated video, printed materials, and social media content, with a community champion-led dissemination strategy. The intervention design draws on established principles for adapting behavioural interventions for minority ethnic communities, including addressing participation barriers, using co-design to support cultural acceptability, and aligning with community values.29 This approach is intended to be flexible, scalable, and cost-effective, making it a strong candidate for wider adoption if proven effective.
1.1 Aim
To test whether a six-month, community champion-delivered intervention increases breast cancer screening uptake in underserved populations, including women from ethnic minority backgrounds and deprived communities.
1.2 Primary Objective
To determine whether a six-month community champion-delivered intervention increases breast cancer screening uptake in a London borough, compared with similar London boroughs without the intervention, overall and within specific and combined underserved groups (minority ethnicity, IMD deciles 1–3).
1.3 Secondary Objectives
1) To examine the cost-effectiveness of a community champion delivered intervention on breast cancer screening uptake.
2) To measure exposure to the intervention and determine whether intervention exposure is associated with more positive attitudes towards breast cancer screening, greater intention to screen and self-reported screening behaviour.
2. Protocol
2.1 Study Design and Conceptual Framework
This study is a pragmatic, quasi-experimental evaluation to determine whether a behavioural science–informed, community champion–delivered intervention can increase BCS uptake in underserved populations. A difference-in-difference design, with inverse probability weighting (IPW) to adjust for covariates, will be used to estimate the causal effect of the intervention. Screening uptake in the intervention borough will be compared with uptake in non-neighbouring comparator boroughs with similar baseline rates and sociodemographic profiles.
The design of the intervention resources is grounded in behavioural science frameworks, including the Behaviour Change Wheel30,31 and the Theoretical Domains Framework.32 Surveys will assess self-reported intervention exposure and impact of exposure on beliefs about BCS, intention to screen, and self-reported BCS uptake.
The intervention will last six months, followed by a six-month follow-up period without active promotion to assess sustained effects.
2.2 Setting and Context
The study will be conducted in the London Borough of Hounslow, selected due to persistently low BCS coverage (60.7% in 202333), high ethnic diversity (55.9% identifying as non-White ethnic groups34), and high levels of socioeconomic deprivation (poverty rate 34%35). Intervention delivery will prioritise neighbourhoods characterised by ethnic diversity and deprivation, which have been identified as areas of low uptake.
Given the borough-wide, community-level nature of the intervention, individual randomisation is not feasible. Similar London boroughs with comparable levels of deprivation, ethnic diversity, and baseline screening uptake and trends in uptake between 2023–2024 and 2024–2025, will be selected as comparators, allowing estimation of the intervention’s effect while accounting for shared regional trends in screening uptake over the study period. They will not be neighbouring boroughs, to minimise the risk of intervention spillover.
2.3 Study Population
The primary population will be all women aged 50–70 invited for BCS in Hounslow during the six-month intervention and six-month follow-up period. The comparison population will be women in the selected comparator boroughs invited for screening during the same timeframe.
Although the intervention is aimed at screening-eligible women, the intervention materials and dissemination will also target wider community members (e.g. partners, peers, and adult children) in order to increase awareness, normalise screening behaviours, and generate indirect encouragement to attend BCS.
2.3 Patient and Public Involvement (PPI)
Patient and public involvement (PPI) was embedded throughout the study design via regular meetings with three diverse public partners from Hounslow, who contributed significantly to the study design. Public partners provided feedback on co-design workshop plans, champion training, campaign materials, recruitment methods and materials for both workshops and champions, and survey wording. They also attended and supported the co-design workshops. One public partner attended monthly meetings with the Imperial College London and Hounslow Council (London Borough of Hounslow) teams on a rotating basis.
Co-design workshops were a core component of public involvement in intervention development, to design the intervention resources. Four workshops in a previous study informed the development of the animated video (n = 25),24 and a further five workshops were conducted in-person in Hounslow for this study (n = 46), to develop the remaining intervention resources (leaflets, wallet cards, posters, bus stop adverts, and social media video content). The training session and materials for community champions were designed using a co-design workshop and meetings with our three public partners. Public partners attended and supported workshop delivery.
2.4 Intervention
2.4.1 Intervention Resources
Intervention design was based on the behavioural science frameworks of the Theoretical Domains Framework32 and the Behaviour Change Wheel36 approach. Influences on BCS uptake, particularly among underserved women, were triangulated from findings from a survey of 922 women,37 a systematic review,21 and interviews and focus groups with women from underserved groups24 ( Table 1). This resulted in a list of high- and medium-priority influences on screening uptake,24 which were mapped onto relevant behaviour change techniques (BCTs)36 using the Theory and Techniques Tool.38 This process was used to inform the co-design of the intervention resources described below, to ensure they addressed key barriers and facilitators to screening adherence. For each BCT-influence pair, prompts were created and refined through co-design workshops (described in section 2.3), with preferred messaging chosen and iterated upon.
Table 1. Priority sub-themes mapped onto the Theoretical Domains Framework (TDF).
The co-design process was employed to produce a set of intervention resources. An animated video (3.5 minutes), available in 16 languages, was developed in collaboration with healthcare designers and an animator from Inclusively,23,24 prior to the present study.23,24 Additional resources were developed during this study: leaflets, wallet cards, posters, bus stop adverts, and short versions of the animated video (30–50 seconds) for social media advertising. Each resource was assessed to ensure that it addressed as many of the high and medium priority influences as possible. The list of influences addressed by each intervention resource and the BCTs included for each is shown in extended data Appendix 1. Hounslow Council supported workshop design, and delivery. Posters, leaflets and wallet cards were translated into ten priority languages in Hounslow: Hindi, Gujrati, Punjabi (Gurmukhi and Shamukhi), Urdu, Bengali, Nepalese, Somali, Arabic, Romanian and Polish. The printed materials incorporate QR codes linking directly to the full animated video. Co-designed posters will be displayed in public spaces and community group settings. Finally, bus stop advertisements will be displayed in high-footfall areas within more deprived neighbourhoods.
2.4.2 Community Engagement Model
A central component of the intervention is dissemination of materials via community champions, recruited through Hounslow Council’s Health Outreach Team (HOT), voluntary organisations, faith groups, and its network of over 140 community connectors. Hounslow Council supported recruitment to workshops and community champion roles, with efforts made to recruit a diverse cohort representative of different groups (e.g. based on ethnicity, languages spoken, and levels of education) within the borough.
Champions were trained to share resources in ways that are culturally sensitive and appropriate for their communities. Training was developed through a co-design workshop, and input from public partners. Five champion trainings were delivered via single 2-hour training sessions, two online and three in-person sessions (in different Hounslow locations), held at different times of day, in order to maximise accessibility. Training included information about BCS, sharing the proposed campaign details and resources developed, as well as group activities with role-play on how to answer questions on BCS. Suggestions of how to disseminate resources were also discussed and included: at work, neighbours, friends WhatsApp groups, Facebook, in-person events such as local, social, ethnic, and cultural community groups, health and wellbeing groups, hairdressers, salons, as well public spaces such as libraries, supermarkets, notice boards in healthcare settings. At the end of the sessions, champions were given Frequently Asked Questions sheets on BCS, a certificate of attendance, a badge and lanyard, and their completed worksheet of how they planned to share information. Champions were paid £50 to attend the training, but subsequent champion activities were voluntary. Fifty-eight champions were recruited, trained and asked to share materials over the six-month intervention period.
During the six-month intervention period, we will continue to engage with Community Champions through optional monthly online drop-in sessions, in-person coffee mornings. These sessions enable Champions to connect with one another, exchange ideas and reflect on their community engagement activities. They also allow the research team to support with any challenges or queries champions have during the duration of their role. There is also a WhatsApp Community group for champions (broadcast only), which allows researchers to share announcements about support sessions, and advice to all champions following coffee mornings or online session, and reminders of intervention resources for sharing.
The intervention dissemination will be further supported by Hounslow Council and the HOT, by taking intervention resources to salons, sending announcements about screening in council newsletters and in mailings to faith groups, and taking printed resources when doing other engagement activities and attending events. The intervention will also be made visible in public spaces, including displays in the HOT offices, bus stop advert boards, and social media advertising of the short videos via the Council Advertising Network.
2.5 Data Collection
2.5.1 Screening Uptake Data
Data on breast cancer screening invitations and attendance during the six-month intervention, and six-month follow-up periods will be obtained from the London Breast Screening Service Administration Hub which covers the intervention borough of Hounslow and all comparator boroughs. Data will be requested as a single extract, at month 15 (three months after the end of the 12-month intervention and follow-up period), allowing for the three-month screening uptake window to elapse. To address limitations in ethnicity recording, hub data will be linked with Hospital Episode Statistics (HES) by NHS England. All data will be pseudonymised and transferred to the Imperial College London’s Big Data & Analytical Unit (BDAU) Secure Environment for analysis.
2.5.2 Survey Data
Two complementary surveys will be used alongside administrative screening uptake data using tablet devices (and paper versions for those who prefer this). A screening site survey (N = 400) will be conducted at BCS sites in Hounslow, collecting demographic information and assessing participants’ exposure to the different intervention resources and communication channels. A community-based survey (N = 500) will be administered following the intervention in community settings (e.g. at events and using street-based recruitment), measuring exposure to the intervention, intention to attend screening, perceived barriers and facilitators to screening, and self-reported screening uptake. The community survey will assess the impact of exposure to the intervention on perceptions about BCS. For both surveys, online consent will be taken in the first part of the survey and entry will be incentivised through optional entry into a prize draw for a £50 voucher.
2.5.3 Community Champions Feedback
Two focus groups will be held with community champions (6–8 participants each) to explore experiences of dissemination and perceptions of community responses. Sessions will be recorded, transcribed, and analysed thematically.39 We will also administer an online evaluation survey via Qualtrics to all Community Champions to assess the self-reported reach, frequency and volume of their community engagement and resource-sharing activities.
2.6 Outcome Measures
The primary outcome of the study is uptake of breast cancer screening within three months of invitation. Secondary outcomes include uptake of breast cancer screening among underserved subgroups, specifically individuals residing in Index of Multiple Deprivation (IMD) deciles 1–3 and those from ethnic minority groups. We will measure the impact on uptake during the six-month intervention period, and a six-month follow-up period.
Additional secondary outcomes include self-reported exposure to intervention resources and dissemination channels; intentions to attend breast cancer screening, and self-reported screening uptake; and alongside perceived barriers and facilitators to participation.
2.7 Sample Size and Power
According to records from the London Breast Screening Service, approximately 3,500 women are invited for BCS in Hounslow every six months, which provides sufficient power for population-level analysis. With a 1:3 ratio of patients in intervention versus comparator boroughs, the study has over 95% power to detect a 3.5% increase in uptake, assuming an unchanged baseline uptake of 63% in comparator boroughs, and 89% power to detect a 3% absolute increase.
Subgroup analyses have 87% power to detect a 6.5% increase in uptake within IMD deciles 1–3 and 88% power to detect a 4% increase in uptake within ethnic minority groups.
The screening site survey (N = 400) is intended for descriptive analysis. The community survey (N = 500) is powered to detect a 0.5-point difference in intention to screen between exposed and unexposed participants on a five-point Likert scale, assuming standard deviation of 1.4.
2.8 Inclusion and Exclusion Criteria
Participants will be eligible for inclusion in the primary analysis of uptake if they were registered as female with a general practitioner (GP), aged between 50 and 70 years at the time of their BCS invitation, and resident in the London Borough of Hounslow (intervention area) or in one of the designated comparator boroughs. Individuals must be invited to participate in BCS during either the intervention or follow-up period. Individuals will be excluded from the uptake analysis based on the exclusion criteria for the Breast Screening Programme10: had a bilateral mastectomy; opted out of the NHS Breast Screening Programme; or declined to receive screening-related communications from the programme. Women not yet due for their next routine invitation, or who have already completed BCS within the current three-year screening interval, will fall outside the study’s invitation window during the relevant period.
Inclusion criteria for the screening site surveys will be anyone attending BCS in Hounslow. Inclusion criteria for the community-based surveys (currently pending approval as a substantial modification) will be females aged 40–75. This age range is wider than the age of screening eligibility, in order to also assess impact of the intervention on those who will be approaching the age of screening eligibility, and those who are recently past the age when they will be invited (given that women over the age of 70 can still request screening).
2.9 Health Economic Analysis
Although breast screening is recommended in the UK at the national level,40 the relationship between socioeconomic status and breast cancer incidence and mortality is complex,41 meaning that increases in uptake in specific locations and communities may not necessarily be cost-effective. A cost-effectiveness analysis from the perspective of the NHS will be conducted using a version of MANC-RISK-SCREEN, an open-source discrete event simulation model based on the UK’S National Breast Screening Programme (NBSP),42–44 reparameterised to reflect the demographics of the study population. A systematic review will be conducted on socioeconomic disparities in breast cancer screening, treatment, and outcomes in the UK, and any identified disparities will be reflected in the reparameterised model. We will estimate incremental costs to the NHS and health benefit in quality-adjusted life years (QALYs) accrued through the changes in uptake estimated from the difference-in-difference analysis, and use these to calculate an incremental cost-effectiveness ratio (ICER) summarising the cost-effectiveness of the intervention in terms of the amount of money in GBP which needs to be spent on the intervention to obtain a single QALY’s worth of health benefit. As the community intervention is specifically intended to improve uptake among underserved groups, an aggregate-level distributional cost-effectiveness analysis will be conducted to quantify the social value of the intervention, focussing on Index of Multiple Deprivation. The health economic analysis will be implemented as open-source software so that it can be easily adapted by researchers and policy planners considering similar schemes in other locations.
2.10 Data Analysis
2.10.1 Uptake Data
Primary analysis will apply a difference-in-difference model comparing pre- and post-intervention uptake between Hounslow and comparator boroughs. Logistic regression will be used to model the odds of uptake, with IPW used to adjust for different population distributions across age, ethnicity, IMD, prior attendance, distance to screening site, and transport accessibility. Sensitivity analyses will assess the robustness to violations of the parallel trends assumption, including the magnitude of differential changes between screening uptake in each borough that would be required to explain the observed effect.
2.10.2 Survey Data
Descriptive analyses will summarise exposure rates. The screening site survey will also assess exposure rates to the different intervention resources and dissemination routes. For the community survey, chi-squared tests will examine relationships between exposure and intentions to screen, and self-reported screening uptake during the intervention period. Regression models will examine associations between exposure, intentions to screen, self-reported screening uptake, and barriers and facilitators to screening, while controlling for demographic covariates.
2.10.3 Community Champions Feedback
Qualitative data from community champions will be analysed using inductive thematic analysis39 to explore dissemination experiences and identify perceived facilitators and barriers.
2.11 Ethics
Several ethical considerations were identified in the design of this study. Targeting the intervention toward women from minority ethnic groups, and women living in areas of high deprivation, was considered ethically justified given documented, well-evidenced inequalities in screening uptake11–13 (see Introduction), rather than presenting risk of stigmatisation. Furthermore, materials were co-designed with the target population to ensure appropriateness and cultural sensitivity.
Written informed consent will be sought from all survey and focus group participants, who may decline to participate. Digital surveys will use a single-checkbox consent procedure, with prize draw entries collected on a separate, unlinked form. Participation in the prize draw incentive is optional and not contingent on screening attendance, to avoid undue inducement. Screening uptake data will be obtained via administrative linkage rather than individual consent, consistent with routine public health surveillance practice. This is because informing participants could itself bias screening behaviour, the approach does not diverge from routine service practice, and consent is not feasible at the scale of London’s screening population (>200,000 invited annually). Researchers will only access pseudonymised data and will not be given the re-identification key. Community champions will receive training and clear boundaries regarding their role.
This study has been approved by North East – Tyne & Wear South Research Ethics Committee and Health Research Authority (HRA) on 6th January 2026 (REC 25/NE/0199/IRAS 346207).
2.12 Dissemination
A robust publication approach is envisaged with aggregated unidentifiable results published in peer review journals and in conference presentations. Local dissemination of findings will take place through Hounslow Councils newsletters, and a plain English summary of the results sent to community champions and workshop participants. To ensure widespread dissemination of the work to relevant stakeholders, dissemination will also include non-academic means such as blog posts and an intervention toolkit to facilitate wider roll out, e.g. by other local authorities, or cancer alliances. No identifiable data will be used in any publication.
3. Discussion
This study will evaluate the impact of a community champion–led intervention to increase BCS uptake in underserved populations in the London Borough of Hounslow. By combining co-designed materials with culturally sensitive dissemination via community members, the intervention addresses barriers that have limited the effectiveness of previous approaches. To our knowledge, the is the first UK study to evaluate a community champion-led intervention focused specifically on BCS using a controlled, quasi-experimental design. While related UK work has explored peer-led approaches across multiple cancer types,27,28 this study is distinct in its exclusive focus on BCS and its borough-wide, population-level evaluation and its findings will provide crucial evidence for national and local strategies aiming to improve screening uptake.
A key strength of the study lies in its co-design approach. Materials have been co-designed with input from women in underserved communities, ensuring cultural and linguistic appropriateness. Translation into multiple languages and the involvement of community champions embeds the intervention within multiple networks, which centrally disseminated campaigns may be less likely to reach. A further strength is the use of established behavioural science frameworks to inform the intervention materials, namely, the Behaviour Change Wheel,30 Theoretical Domains Framework,32 Theory and Techniques Tool,38 and BCT Taxonomy36 which few comparable community champion interventions to date have applied systematically to intervention design. The integration of BCTs, including ‘credible source’ and ‘social support’, enhances the likelihood of effectiveness. The study has an equity focus built into its design, rather than just assessed at analysis stage: subgroup analyses by ethnicity and deprivation are pre-specified as primary and secondary objectives and thus powered for, allowing a more rigorous assessment of whether the intervention reduces existing disparities in screening uptake. The mixed-methods evaluation, which combines administrative data with surveys and qualitative focus groups, provides a comprehensive assessment of the intervention impact and mechanism of impact.
The pragmatic, quasi-experimental design is appropriate for testing a population-level community intervention in a real-world setting. The use of difference-in-difference analysis with inverse probability weighting will strengthen causal inference by accounting for population differences between Hounslow and comparator boroughs.
Nevertheless, several limitations must be acknowledged. The non-randomised design introduces potential for unmeasured confounding, despite the use of statistical adjustments. A related limitation concerns the difference-in-differences approach itself: its validity relies on the assumption that intervention and comparator boroughs would have followed similar trends in screening uptake in the absence of the intervention. This cannot be directly tested prior to the study and may be impacted if unobserved local factors, such as differential changes in screening service capacity, local health promotion activity, or population turnover, diverge between boroughs during the study period. We have tried to mitigate this by liaising with associated Cancer Alliances and the London Breast Screening Service to understand any campaigns/local work which might have an impact upon local trends in BCS uptake during the intervention period. Exposure to intervention materials cannot be fully verified at the individual level, and survey measures of exposure and intention may be subject to recall or reporting bias. Comparator boroughs will be selected as non-contiguous with Hounslow to reduce the risk of spillover; however, this cannot eliminate contamination risk, since some champions may disseminate materials via social media, or other ways which may spread to other boroughs. The intervention is being tested in a single London borough, which may limit generalisability to other contexts with different demographic and service structures. The follow-up period may also be insufficient to capture the intervention’s full effect: as NHS Breast Screening Programme operates on a three-year recall cycle, campaign exposed women not yet due for invitation during the six-month intervention and six-month follow-up window will not be captured within the primary uptake analysis, meaning a null finding could reflect timing rather than true ineffectiveness. This follow-up period is consistent with comparable community-placed cancer screening intervention studies, which have similarly used a six-month follow-up to allow sufficient time for screening uptake to occur following invitation or intervention exposure.45,46 Finally, as with any community-based programme, the fidelity of implementation may vary across champions and settings.
Despite these challenges, the study has important implications. If effective, the intervention offers a scalable and cost-effective model that could be adopted by local authorities and the Department of Health and Social Care to increase BCS uptake, particularly in underserved groups. Such a model would align with the National Cancer Plan’s19 emphasis on strengthening community-based partnerships to reduce screening inequalities. Findings may also extend to other screening and prevention programmes, such as cervical and bowel cancer, and to vaccination campaigns. In addition, by embedding the evaluation within a behavioural science framework, the study will contribute to a growing evidence base on the role of trusted community members in reducing health inequalities.
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Salman M, Egeli A, Humphrey A et al. Protocol of a Community Champion led breast cancer screening intervention for underserved groups [version 1; peer review: awaiting peer review]. NIHR Open Res 2026, 6:202 (https://doi.org/10.3310/nihropenres.14454.1)
NOTE: If applicable, it is important to ensure the information in square brackets after the title is included in all citations of this article.
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