Protocol for a Cohort Study on Lung Cancer Diagnostic Pathways and Outcomes in Ireland

Challenges in timely diagnosis

Early diagnosis is critical for improving survival, as lung cancer detected in its initial stages is more amenable to treatment^4,6,7. However, early-stage lung cancer often presents asymptomatically or with nonspecific symptoms, leading to diagnostic delays^4,8,9. In Ireland, approximately 26.1% of lung cancer cases are diagnosed following emergency presentation². While emergency diagnosis shortens the time from referral to diagnosis, it is also linked to a 9-fold increased risk of 1-month mortality compared to non-emergency diagnostic pathways¹⁰. In Ireland, approximately 26.1% of lung cancer cases are diagnosed following presentation to the emergency department². While emergency diagnosis shortens the time from referral to diagnosis, it is also linked to a 9-fold increased risk of 1-month mortality compared to non-emergency diagnostic pathways¹⁰.

Several factors impede early diagnosis, including patient-related delays in seeking care and difficulties faced by general practitioners (GPs) in differentiating lung cancer symptoms from more common conditions^4,8,9. Such challenges highlight the need to understand how diagnostic pathways function within the Irish healthcare context.

Existing knowledge

The diagnosis of lung cancer in Ireland involves multiple steps across primary, secondary, and tertiary care. The introduction of Rapid Access Lung Cancer Clinics (RALCCs) in 2009, as part of the National Cancer Control Programme (NCCP), aimed to streamline diagnosis and improve timely access to care^11,12. Approximately 50% of lung cancer cases in Ireland are diagnosed through RALCCs, but over 60% of these cases are already at an advanced stage (Stages III and IV), indicating a need for earlier detection^12,13. Lung cancer also has the fifth highest proportion of cases presenting as emergencies among all cancers in Ireland². Approximately 50% of lung cancer cases in Ireland are diagnosed through RALCCs, but over 60% of these cases are already at an advanced stage (Stages III and IV), indicating a need for earlier detection^12,13. Lung cancer also has the fifth highest proportion of cases presenting as emergencies among all cancers in Ireland²

RALCCs typically provide an appointment within 10 days of referral, with 99% occurring within 15 days^11–13. In contrast, the National Optimal Lung Cancer Pathway in England aims for CT thorax within 72 hours of referral for patients with suspected lung cancer and completion of diagnostic investigations, staging and treatment plan within 28 days of referral¹⁴. Patients referred to RALCCs undergo a non-contrast chest CT, followed by further investigations as necessary. Although survival rates have improved for patients managed within the RALCC framework, its utilisation remains suboptimal, partly due to GPs limiting referrals to cases with definitive signs of lung cancer¹³. However, surveyed healthcare professionals perceived the RALCC’s as underused with many GP’s referring patients only when there is definitive signs of lung cancer¹¹. Consequently, patients diagnosed outside of RALCCs often face poorer outcomes^11,15.

A UK study by the National Cancer Intelligence Network found that approximately one-third of patients diagnosed via emergency pathways had presented to their GP before their diagnosis, often requiring multiple visits¹⁵. Given the similarities between the role of GPs within the respective healthcare systems, understanding these diagnostic patterns in Ireland is critical for enhancing diagnostic interventions and reducing system inefficiencies.

Unmet needs

Despite the importance of early diagnosis, there is a limited understanding of lung cancer diagnostic pathways in Ireland. Barriers to timely diagnosis include geographical access, socioeconomic factors, lack of awareness, and misinterpretation of symptoms¹⁶. Additionally, financial constraints, particularly for patients without government subsided primary care, may lead to delayed GP consultations when symptoms are attributed to comorbidities or smoking history. A comprehensive evaluation of diagnostic pathways, patient characteristics, and system-level factors is essential to identify and address obstacles to timely lung cancer diagnosis.

Aim and objectives

This study aims to characterise diagnostic pathways for lung cancer at the Beaumont RCSI Cancer Centre and assess their impact on diagnosis timeliness and clinical outcomes. The specific objectives are:

Study design and setting

This is a single-centre, retrospective cohort study aiming to investigate the diagnostic pathways of patients with lung cancer at Beaumont Hospital, Dublin, over an 11-year period (1st January 2012 to 31st December 2023). Beaumont Hospital serves as a tertiary referral centre and is part of the Beaumont RCSI Cancer Centre (BRCC), providing a comprehensive setting to capture data on lung cancer diagnosis and management.

Participants and eligibility criteria

The study cohort is drawn from the BRCC Lung Cancer Registry, which prospectively collects data on all lung cancer patients diagnosed and treated at Beaumont Hospital. Eligible participants include patients with a primary diagnosis of lung cancer during the study timeframe. Exclusion criteria are:

Focusing on newly diagnosed primary lung cancer cases ensures analysis of initial diagnostic pathways, avoiding confounding by recurrent or metastatic disease

Data source and variable definitions

Data will be sourced from the BRCC Lung Cancer Registry, which integrates information from medical records. Key variables include:

Appendix 1 provides a detailed list of variables and definitions.

Data quality and bias minimisation

To mitigate selection bias, all eligible patients from the registry during the specified period will be included, ensuring a complete case capture. Recall bias is minimised through the use of prospectively collected registry data. Additionally, the registry data undergoes regular validation and cleaning processes, ensuring reliability. Temporal delays in data collection (>1 year from event) will be reported, and any potential impact on analyses will be discussed.

Data access and management

The BRCC Lung Cancer Registry data is accessed via the Beaumont Cancer Clinical Trials and Research Unit, with approval from the Clinical Governance Department of Beaumont Hospital. All identifiable patient data is anonymised prior to analysis, in compliance with data protection policies. Data extraction and management processes will be systematically documented to ensure reproducibility.

Statistical analysis plan

Analysis will address the study objectives in five phases:

1. Descriptive analysis: Sociodemographic and clinical characteristics will be summarised, including smoking status and pulmonary function test data, to provide an overview of the cohort.

2. Pathway categorisation: Diagnostic pathways will be mapped, analysing the sequence of care and timelines from presentation to diagnosis. The distribution of referral types and pathway characteristics will be assessed by patient demographics.

3. Relationship with disease stage: Associations between diagnostic pathways and cancer stage at diagnosis will be examined using frequency analysis and Kaplan-Meier survival curves to illustrate diagnostic milestones.

4. Treatment decisions: Multivariate logistic regression will identify factors influencing initial treatment modalities, incorporating demographics, clinical features, and referral pathways.

5. Survival outcomes: Kaplan-Meier survival curves and Cox proportional hazards models will evaluate the impact of diagnostic pathways on survival, adjusting for confounders. Sensitivity analyses will test the robustness of findings.

Statistical analyses will be performed using software such as R or Stata, with appropriate coding for regression analyses, survival modelling, and variable transformations.

Ethical considerations and reporting

This study utilises data collected as part of a clinical audit approved by Beaumont Hospital’s Clinical Governance Department (Registration number CA2024/136). Data access for anonymised lung cancer records (2012–2023) was granted by the Cancer Clinical Trials and Research Unit (Registration number CDR 115). As no identifiable data is used, individual patient consent was not required. The study will follow the RECORD reporting guidelines for transparent reporting of observational research using routinely collected health data.

Key results and anticipated contribution

This study aims to provide a comprehensive analysis of the diagnostic pathways for lung cancer within a major Irish healthcare setting, with the goal of identifying critical delays and contributing factors in the diagnosis process. By delineating these pathways and understanding their variability, the findings are expected to identify bottlenecks in care, evaluate the impact of different referral sources, and provide insights into how early diagnosis can be facilitated. Moreover, this analysis will contribute to a more nuanced understanding of the Irish lung cancer diagnostic landscape, highlighting areas for potential intervention and improvement.

Comparison with existing literature

The study’s context-specific focus on the Irish healthcare system will enable a comparison with similar cohorts and pathways internationally, offering valuable insights into diagnostic disparities. Prior research from other healthcare systems, such as the UK, has identified key challenges in emergency presentations and delayed diagnoses in primary care (Swann et al., 2024). This study will further our understanding of whether these patterns are consistent or divergent in Ireland, particularly in light of the implementation of Rapid Access Lung Cancer Clinics (RALCCs). Such a comparison will allow for the identification of system-level facilitators and barriers that are unique to the Irish context while exploring potential parallels with other countries.

Strengths and limitations

This study benefits from its cohort design within a single tertiary care centre, which allows for detailed examination of diagnostic pathways from initial symptoms to confirmed diagnosis and treatment. By incorporating data from both primary and secondary care, it provides a comprehensive view of patient pathways, including referral patterns, presenting symptoms, and diagnostic timelines.

There are, however, some limitations. The single-centre focus at Beaumont Hospital may limit the applicability of findings to other regions in Ireland, particularly as diagnostic pathways may vary between urban and rural settings or across different healthcare systems. Additionally, the study is reliant on registry data from patients managed within Beaumont Hospital, which may not fully represent the experiences of individuals diagnosed or treated in other settings. This could lead to underrepresentation of patients with atypical presentations or delays in care-seeking. This will be mitigated with transparency in reporting, strategies for imputation where appropriate and sensitivity analysis.

The reliance on routinely collected data also poses challenges, including potential gaps or inconsistencies in documentation, particularly for events that occurred over a year prior to data entry. Variations in clinical recording practices over time may influence the completeness and accuracy of the dataset

Implications for practice, research & policy

The insights gained from this study could significantly impact clinical practice. By highlighting the common symptoms and demographic factors associated with delayed diagnosis, primary care physicians and specialists can be more vigilant in identifying potential lung cancer cases. This could lead to more prompt referrals and diagnostic testing, ultimately reducing the time to diagnosis and improving patient outcomes.

Our findings will have important implications for healthcare policy in Ireland. Identifying inefficiencies and disparities in the diagnostic process can inform the development of targeted policies aimed at improving access to diagnostic services and reducing waiting times. Policy changes guided by this research could lead to more efficient use of healthcare resources and better allocation of funding towards areas in need of improvement. This study opens several avenues for future research. Longitudinal studies could provide further insight into the progression of lung cancer symptoms and the long-term outcomes of patients based on their diagnostic journey. Additionally, research focusing on interventions aimed at reducing diagnostic delays could be highly beneficial.