The goal of this observational study is to evaluate if a blood test for circulating progastrin (hPG80) and transposable elements (TEs) can accurately predict colorectal cancer (CRC) or polyps in adult patients referred to the 2-week wait (2WW) or Straight to Test (STT) pathways for suspected lower gastrointestinal cancer.

The main questions it aims to answer are:

Can plasma hPG80 levels accurately predict a diagnosis of CRC or polyps in patients undergoing standard 2WW investigations? Can transposable elements (TEs) in the plasma serve as predictive biomarkers for CRC diagnosis in these patients? What are the patient preferences for different diagnostic tests for CRC, particularly a blood-based test compared to more invasive methods?

Participants will:

Provide a 20ml blood sample during a routine hospital visit for their 2WW diagnostic test (e.g., colonoscopy, CT Colon).

Undergo standard clinical investigations as determined by their treating clinicians.

Have their final diagnosis (cancer, polyp, or normal) correlated with their plasma hPG80 levels.

For a subset of 100 participants (25 with confirmed CRC, 75 non-cancer), have their plasma analyzed for circulating signatures using RNAseq and DNAseq.

Complete an electronic post-study questionnaire to explore their preferences and experiences with different CRC diagnostic tests used within the 2WW pathway.

Current Challenges in CRC Diagnosis Currently, the 2WW pathway for bowel symptoms typically involves a stool-based faecal immunochemical test (FIT) before referral. While the 2WW pathway is vital for expedited diagnosis, a systematic review from 2009 revealed that only 9.5% of patients referred with lower gastrointestinal (GI) symptoms through this pathway are ultimately diagnosed with cancer. This low positive predictive value places immense pressure on an already overstretched healthcare system, leading to unnecessary invasive investigations, increased costs, and prolonged patient anxiety. There's a clear need for more accurate and less invasive diagnostic tools to better stratify patients.

Progastrin (hPG80) as a Biomarker hPG80, a circulating blood biomarker, is a precursor to gastrin and has shown promise in detecting various GI cancers, including CRC. In healthy individuals, hPG80 is typically undetectable as it's converted to gastrin. However, elevated hPG80 levels can be found in the plasma of many patients with both early and advanced GI malignancies. Studies have shown an elevated hPG80 level in CRC subjects compared to those with benign polyps. This study will investigate whether plasma hPG80 levels can accurately predict CRC or polyps in 2WW patients and distinguish the absence of cancer based on PG levels.

Transposable Elements (TEs) as Biomarkers Transposable elements (TEs), which are mobile genetic elements, are also emerging as potential cancer biomarkers. Recent research has linked TEs to various cancers, including CRC. The Dr. Madapura's lab has shown that transposable element-derived RNA signatures can be superior predictors of diseases. This study will explore the role of TEs in predicting CRC diagnosis within the 2WW referral cohort. Specifically, it will identify and evaluate TEs in the plasma of these patients as potential predictive biomarkers. The analysis will involve RNA sequencing (RNAseq) and nanopore DNA sequencing (DNAseq) of plasma samples to look for transcript signatures and epigenetic modifications of DNA.

Study Design and Population This is a prospective, observational, cohort study conducted at Barts Health NHS Trust, initially focusing on the Royal London Hospital site. The study will recruit 582 adult patients referred via the 2WW or Straight to Test (STT) pathways for suspected lower GI cancer. Eligible patients will be aged over 18 years, have no history of inflammatory bowel disease, and have a performance status of ECOG 0-2 (or 3, pending clinical assessment). Patients with a family history of CRC are not excluded. Those with a documented familial type of CRC, untreated solid organ cancers, or who are not fit for standard investigations will be excluded.

Data Collection and Analysis Upon informed consent, a 20ml venous blood sample will be collected from participants at their first clinical appointment, usually during a routine hospital visit for their 2WW diagnostic test (e.g., colonoscopy, CT colonography). This sample will be used for both PG and TE analysis. Plasma PG levels will be measured, and a subset of 100 samples (25 confirmed CRC and 75 non-cancer samples) will undergo RNAseq and DNAseq for TE analysis.

The primary objective is to determine the sensitivity and specificity of plasma hPG80 levels in diagnosing CRC and benign colonic polyps. This will involve calculating positive and negative predictive values, and performing Receiver Operating Characteristic (ROC) curve analysis to assess the discriminatory ability of PG.

The secondary objective is exploratory and focuses on identifying and validating novel TEs as potential biomarkers for CRC diagnosis. This will involve the RNAseq and DNAseq analysis of the selected 100 samples.

A tertiary objective involves a post-study patient questionnaire survey to understand patient preferences and choices regarding CRC diagnostic tests, exploring their experience with a blood-based test compared to more invasive methods. This will be distributed electronically via SurveyMonkey™.

Expected Outcomes and Benefits

The study aims to provide crucial insights into whether adding a simple blood test (hPG80 and/or TE analysis) to the existing 2WW pathway can:

Improve diagnostic accuracy and speed: Leading to more effective and timely treatment.

Alleviate patient stress: By providing quicker and more accurate diagnoses, reducing anxiety associated with uncertainty.

Reduce unnecessary invasive procedures: Potentially avoiding colonoscopy-related complications and overall costs for the NHS.

Prioritize urgent cases: By better stratifying patients, allowing healthcare resources to be directed to those most in need.

There are no direct benefits to the study participants, but the knowledge gained is expected to have a significant long-term clinical impact on screening for suspected lower GI malignancies.

The study is funded by a research grant from LAPResearch UK.

Inclusion Criteria:

• Adult, lower GI 2WW and or Straight to Test (STT) referral patients with suspected lower GI cancer.
• Male and Female patients aged >18 years.
• 2WW referral patients with no history of inflammatory bowel disease.
• Performance status (ECOG 0-2; and 3 pending clinical assessment of fitness).
• Patients with capacity to consent to the study.

Exclusion Criteria:

• Any patients referred outside of the 2WW and or STT referral pathways with suspected Lower GI cancer or those referred as an emergency with or suspected CRC.
• Age < 18 years.
• Patients not fit for standard investigations (e.g. not fit for gastroscopy, colonoscopy or CT colonography) in the 2WW pathway.
• Patients with no capacity to consent or who declined consent for participation.
• Patients with untreated solid organ cancers.
• Patients with known inflammatory bowel disease.
• Patients with documented familial type CRC.

All adult patients who are referred by the GPs to the Barts Health NHS trust under the 2WW referral pathway and the STT pathway would be potentially eligible. We are planning to recruit patients initially only from the Royal London Hospital site and there is potential to expand recruitment to other hospital sites of Barts Health NHS Trust, if necessary.

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