The goal of this prospective interventional biomarker development and validation study is to determine whether circulating tumour DNA (ctDNA) can be detected in patients with large pre-neoplastic colorectal lesions undergoing endoscopic resection and whether ctDNA can be used to identify local recurrence after resection.
The main questions it aims to answer are:
* Can advanced colorectal laterally spreading tumours (LSTs) shed detectable ctDNA into the bloodstream before endoscopic resection? * Can ctDNA measured at the first surveillance colonoscopy detect or predict local recurrence after endoscopic resection?
Participants will:
* Provide a blood sample before their planned endoscopic resection procedure for ctDNA analysis. * Undergo standard endoscopic resection of their colorectal lesion. * Allow collection and molecular analysis of tissue samples obtained from the resected lesion. * Allow researchers to collect clinical, endoscopic, pathological, and molecular data from their medical records for research purposes.
The study does not alter the standard clinical management, resection technique, or surveillance schedule. The only study-specific procedures are blood sample collections performed during routine intravenous catheter placement for the participant's endoscopic procedures.
Age ≥ 18 years.
Referred for resection of a large (≥ 10 mm) colorectal laterally spreading tumour (LST).
Lesion judged amenable to endoscopic resection by the treating endoscopist.
Able to provide written informed consent.
Known concurrent or prior colorectal cancer, or another active malignancy that could contribute circulating tumour DNA.
Lesion < 10 mm.
Inability to provide informed consent.