Defensiveness in Cancer Screening and Prevention: A Scoping Review of Definitions, Measures and Profiles

Background and rationale

Screening plays a crucial role in cancer prevention by detecting pre-cancer or early-stage cancer, when it is typically easier to treat, and where outcomes are more favourable.¹ In some cases, screening tests can prevent cancer from developing by identifying and removing abnormal cells before they become cancerous, such as polyps found during screening or diagnostic colonoscopy² (for colorectal cancer screening) or cervical intraepithelial neoplasia (CIN) detected through diagnostic colposcopy³ (for cervical cancer screening). Studies indicate that implementing screening programmes and evidence-based prevention correctly, and at scale, can achieve substantial population benefits and reduce the burden of cancer on populations.⁴

Organised population-based cancer screening involves inviting an identified population to undergo a screening test, usually at a defined interval, to identify early stage or precancerous lesions in order to reduce mortality, and where possible, incidence of those cancers in the population.^2,3,5 Population-based screening has been implemented in many countries for breast, cervical and colorectal cancer, particularly in Europe.^3,6,7 Lung cancer screening for defined high risk groups has also become available in several countries in the Europe^8,9 as well as the United States.¹⁰ There is also growing potential and interest in screening for gastric, prostate,¹¹ oesophageal and ovarian cancers.¹² Multi cancer early detection (MCED) tests¹³ also exist, although evidence on their use in asymptomatic populations is less solid.¹⁴

The success of organised cancer screening programmes in maximising health benefits (reducing cancer mortality and incidence) depends in large part on achieving high uptake within the programme’s target population.¹⁵ In Europe, screening uptake varies substantially; breast cancer screening uptake is between 23–84%, cervical cancer screening between 40–81%¹⁶and colorectal cancer screening between 23–71%.⁷ Many cancer screening programmes have also observed disparities in uptake by sex, age and socioeconomic deprivation.^17–19

Reports from the National Screening Service (NSS) in Ireland on BreastCheck, CervicalCheck and BowelScreen (Ireland’s national population-based cancer screening programmes) indicated that screening uptake for these programmes was 70%, 75% and 46% respectively. However, the uptake rates were lower among older people in the three programmes (cervical, 60+ years: 30%; breast, 60+: <30%; colorectal, 65+: 10% (for initial invitees))^20–22 which has also been observed in the UK.²³

Multiple strategies to improve cancer screening participation have been investigated and effectiveness varies.^24–28 Strategies that have been shown to increase uptake include general practitioner (GP) endorsements, telephone outreach, advance notifications, and offering simplified screening tests (HPV testing over pap smear for cervical cancer screening; Fecal Immunochemical test (FIT) over the guaiac Fecal Occult Blood Test (FOBT) for colorectal cancer screening), especially when paired with reminders, provider alerts, or vaccinations.^25,29 However, many uptake intervention studies show limited success, likely in part due to a lack of theoretical grounding or understanding of the determinants of screening behaviour.^24,30,31

The rationale for this scoping review emerged from previous theoretically informed research on colorectal cancer screening uptake in Ireland.^18,32–35 Previous studies have identified socio-demographic and socio-economic barriers to colorectal, breast and cervical cancer screening participation in Ireland.^32,36 Moreover, cancer fatalism, emotions (disgust about the screening test; a belief that screening is tempting fate), and attitudes (“cancer cannot be cured”)³³ have been reported to be independently associated with non-participation in colorectal cancer screening.^33,34

Growing evidence suggests that defensive reactions to health messages (messages which are primarily aimed at improving health and healthy behaviours) can lead to rejection of these messages (for instance, counterarguing: “I feel fine, I don’t need to be tested”).³⁷ McQueen and colleagues describe this phenomenon – known as defensive information processing - thus³⁸:

McQueen et al.’s conceptual model and measure of defensive information processing for colorectal cancer screening includes four domains³⁷: (1) attention avoidance (reducing awareness by avoidance); (2) blunting (active mental disengagement through avoidance and accepted denial); (3) suppression (acknowledging others’ risk but avoiding personal inferences through self-exemption beliefs); and (4) counter-argumentation (arguing against the evidence). Clarke et al. have reported that defensive information processing (message suppression) is independently associated with non-participation in colorectal cancer screening in Ireland.³⁴

The literature on Defensive Information Processing in cancer screening is diverse, spanning multiple theories, cancer types, and methodologies. Evidence on defensiveness in this context is fragmented across disciplines like health psychology,^39,40 behavioral medicine,³⁴ and communication science,⁴¹ with inconsistent terminology, conceptual definitions, theoretical frameworks, and measurement tools.

Establishing a comprehensive understanding of current research on factors and domains consistent with the defensive information processing conceptual framework and measure is critical for guiding the future design of cancer screening interventions. Studies conducted since the original model by Blumberg,⁴² and following McQueen et al.’s development of the defensive information procesing conceptual model will act as the starting point for this review.

Despite growing interest in defensive information processing within cancer screening contexts, no systematic or scoping reviews have synthesized this evidence base to date. Existing reviews on related constructs such as psychological distress or defensive reactions^43,44 to health messages do not specifically address these factors in cancer screening. A scoping review will therefore fill a critical gap by mapping existing research, clarifying conceptual definitions, identifying measurement tools, and describe intervention strategies aimed at reducing defensiveness.

Review objective

This scoping review will provide an overview of the current evidence on Defensive Information Processing and its domains, in cancer screening, within the context of McQueen et al.’s^37,38 conceptual model.

Research question

What is currently known about defensive information processing in cancer screening research?

Eligibility criteria

Eligibility criteria for this study have been defined using the population, concept and context (PCC) framework described by JBI⁴⁶ ( Table 1). Quantitative studies that focus wholly or in part on measuring any Defensive Information Processing domains (attention avoidance, blunting; suppression; and counter-argumentation) in cancer screening research will be eligible for inclusion. Eligible studies will include randomized control trials, non-randomized control trials, uncontrolled studies, quasi-experimental studies, natural experiments of interventions and observational studies (cohort, case-control and cross-sectional designs). Qualitative studies will be excluded as they will not report quantitative defensiveness measures or intervention outcomes. English language full-text papers published in peer-reviewed journals will be eligible for inclusion. While we do not have the resources to assess studies in languages other than English, we will record and report on the number of these studies retrieved.⁴⁷

Information sources and search strategy

The following electronic databases will be searched: Scopus, Web of Science, EMBASE, Medline, CINAHL, PsycINFO, and the Cochrane Central Register of Controlled Trials (CENTRAL). The search strategy will be developed in collaboration with an information specialist to ensure methodological rigor and comprehensive coverage.

An initial limited search of EMBASE and Medline will be undertaken to identify key articles relevant to defensiveness in cancer screening (Appendix 1). The keywords and index terms extracted from these articles will inform the development of a refined and comprehensive search strategy. This strategy will then be reviewed and adapted for use across all target databases. A forward citation search will be performed and the reference lists of all included studies will be manually screened for additional relevant publications. Citation searches of relevant reviews also will be conducted. All databases will be searched from 2000 (the year Blumbergs⁴² information processing model was published) to the commencement date of the scoping review.

Study selection

Search results will be uploaded to the web-based Covidence platform to manage each stage of the scoping review including de-duplication, title and abstract screening, full-text review and data extraction.

To determine eligibility, two reviewers will independently screen titles and abstracts for inclusion and exclusion criteria, with disagreements resolved through discussion and, where required, a third reviewer to ensure consensus. Among eligible abstracts, all full-text articles will then be reviewed independently by both reviewers with disagreements resolved through discussion and, where required, a third reviewer. Reasons for excluding at full text screening stage, along with the final numbers of included and excluded studies at each stage of the review, will be documented and reported in a PRISMA flow diagram.³⁸

Data charting/Collection/Extraction

A standardised data extraction template will be designed and piloted to extract and code relevant data ( Table 2). Data will be extracted on cancer type, use of theory and conceptual frameworks, defensiveness definitions and measures (related to Defensive Information Processing domains; attention avoidance, blunting, suppression and counter-arguing) and interventions utilised within included studies (charted using the TIDiER framework⁴⁸ and including rationale, theory or goal of the intervention, intervention type, delivery mode, intervention provider and intervention materials). In addition, sociodemographic characteristics of study participants, the nature and setting of the behaviour under study, and outcomes related to defensive information processing domains will also be extracted. Where information is missing or unclear, study authors will be contacted. Any missing, redundant or unclear information will be discussed with all co-authors.

Synthesis and presentation of results

The review will use a narrative synthesis approach according to SWiM guidance.⁴⁹ Extracted data will be coded, categorised and a descriptive analysis will be conducted. Where data is available and appropriate, we will explore how interventions in cancer screening, which have targeted defensive information processing domains, are implemented and targeted at sub-groups (e.g., sex, age, socio-economic status). Data will be presented in aggregate formats such as tables and appropriate visual representations.

Ethics and dissemination

This study is based on a review of existing published and publicly available reports and no ethical approval is required. Registration of this review on OSF will enhance transparency and reproducibility. Stakeholders, including public and patient representatives, healthcare professionals and the National Screening Service will be consulted throughout the review process and will ensure our findings are relevant and appropriate for the development of future interventions. Dissemination of findings will be conducted through various methods such as peer review publications, national and international conferences and seminars, and within other stakeholder forums.