Secondary Care Colorectal Cancer Pathway Review

Design:

This is a retrospective observational cohort data-analysis study of patients managed within the NHS Lothian colorectal cancer (CRC) urgent suspicion of cancer (USoC) pathway and patients referred urgently to the Colorectal department from April 2022 to August 2025. April 2022 corresponds to the start of double FIT testing within the pathway. 5-year follow-up will be included (up to August 2030) to include 5-year cancer outcomes.

Methods:

Patients will be identified from our pathway. Estimated ~25,000 patients will be included. Data will be collected on patient characteristics, past medical and prescribing history, hospital presentations and investigation outcomes, cancer outcomes and mortality data. Linkage to relevant patient datasets will be required.

A service review of the USoC/urgent pathway will focus on key performance indicators such as time to diagnosis and treatment, as well as patient journey pathways (Sankey plots) and re-referral rates.

Furthermore, data will be analysed using standard methods such as odds-ratio multivariate logistic regression to determine any significant associations which enrich for CRC and significant bowel pathology in this patient group. Significant bowel pathology includes advanced adenoma, advanced colorectal neoplasia and inflammatory bowel disease (IBD). Importantly, the modelling will only utilise readily available information from the electronic health record (EHR) such as age, sex, blood haemoglobin, BMI and SIMD to improve pre-test probability by restricting the target population.

Markov models will be formed as part of the health economic analysis, and the financial cost per case detected within the pathway will be calculated. We will explore the impact of waiting times on disease progression and the associated impact on the financial costs of treatment and patient quality of life.

Results from the above analyses will be incorporated into a decision-flow as guidance for referrals to secondary-care.

Sample size calculation:

To perform regression analysis, at a significance level of 0.05, medium size effect and 10 predictors, 170 cases of CRC are required. Our database of ~25,000 patients has approximately 500 cases of CRC. There will be minimal anticipated drop-out. Therefore our required sample size will be achievable.22

Proposed analyses:

Standard summary statistics of the pathway will be reported (means, standard deviations, medians, inter-quartile range). Multivariate logistic regression will be performed to determine risk-factors significant for CRC at different FIT levels. Subgroup analyses will take place within different FIT result thresholds (<10, 10-79, >79 µgHb/g) as well as between cancer and non-cancer patients, and for other significant bowel pathology. Long-term outcome data will be analysed, up to 5 years.

Furthermore, a service evaluation of the USoC/urgent pathway will focus on key performance indicators such as time to diagnosis and treatment, as well as patient journey pathways (Sankey plots) and re-referral rates. Markov models will be formed as part of the health economic analysis, and the financial cost per case detected within the pathway will be calculated. We will explore the impact of waiting times on disease progression and the associated impact on the financial costs of treatment and patient quality of life. The rate of interval cancers over long-term follow-up will be calculated.

We do not anticipate a significant amount of missing data. Data entries will be removed due to missing data on an analysis-by-analysis basis.

Inclusion criteria

Patients managed within the NHS Lothian CRC USoC/urgent pathway (including urgent referrals) due to 'red-flag' symptoms concerning of CRC from April 2022 to August 2025.

Exclusion criteria

• Under the age of 18.
• History of inflammatory bowel disease.
• Under polyp surveillance.
• Previous diagnosis of CRC.