Tumor recurrence significantly affects survival rates following the local resection of submucosal colorectal cancers (T1 CRC). Despite this, there are currently no reliable biomarkers established to predict recurrence in T1 CRC.

This study seeks to improve the prediction of recurrence-free survival in individuals who have survived T1 CRC.

The incidence of invasive submucosal colorectal cancer (T1 CRC) is increasing, likely as a reflection of improved screening and endoscopy use. Current treatment options for T1 CRC focus on less invasive methods (i.e., endoscopic submucosal dissection), and treatment decisions are based on the risk of lymph node metastasis (LNM). Up to 70-80% of T1 CRC patients may undergo surgery, with adjuvant chemotherapy recommended only for those with LNM.

However, current clinical practice guidelines are considered to be overly aggressive and recommend the administration of aggressive treatment to many patients who may be cured with non-invasive therapy alone. This results in the overtreatment of many patients, especially those that are currently defined as 'high-risk' T1 CRC. Existing surveillance methods may not adequately predict the prognosis of T1 CRC, lacking established biomarkers for assessing disease-free survival.

This study seeks to validate tissue-based biomarkers (micro-RNA and messenger RNA) that are associated with tumor recurrence after curative resection. The identification of patients at high risk of recurrence may help in the selection of patients who truly benefit from additional oncologic surgery or adjuvant therapy. Previous research by this group has identified miRNA signatures for detecting postoperative tumor recurrence and metastasis in CRC, highlighting their potential as biomarkers for disease progression.

Inclusion Criteria:

• Stage I, pT1 colorectal cancer (TNM classification, 8th edition).
• Received standard diagnostic, staging, and stage-specific curative-intent resection (endoscopic or surgical, as per local guidelines).
• Confirmed cancer-free survivorship at the time of study inclusion.

Exclusion Criteria:

• Lack of informed consent.
• Induction of neoadjuvant systemic therapy before colorectal cancer resection.
• Synchronous colorectal and non-colorectal cancer diagnosed at or before surgery.

Two cohorts of patients with T1 colorectal cancer

Data collected for the study will be made available to others, including de-identified participant data, at publication, via a signed data access agreement and at the discretion of the investigators' approval of the proposed use of such data.