Calibrated Absolute Risk of Lymph-Node-Metastasis After Non-curative Endoscopic Resection of pT1 Colorectal Cancer

Area of Science:

• Oncology
• Gastroenterology
• Pathology

Background:

• Endoscopic resection of T1 colorectal cancer (CRC) relies on high-risk features for surgery decisions.
• Current criteria are broad and do not offer individualized lymph-node-metastasis (LNM) risk estimates.

Purpose of the Study:

• To develop and validate a composite pathologic score for predicting LNM risk in T1 CRC patients post-endoscopic resection.
• To provide a more individualized risk assessment to guide surgical recommendations.

Main Methods:

• A retrospective analysis of 1162 T1 CRC patients who underwent radical resection after endoscopic resection (2004-2024).
• A composite score (0-5) was created by assigning one point each for five adverse histologic features: lymphatic/venous/perineural invasion, tumor budding, poor differentiation, deep submucosal invasion (≥2000 μm), and positive resection margin.

Main Results:

• 148 patients (12.7%) had LNM. The composite score demonstrated a stepwise increase in LNM risk (6.6% for score 0 to 66.7% for scores 3-4).
• A score of ≥2 identified a high-risk group (35.1% LNM) versus low-risk (9.5% LNM), with an odds ratio of 4.79.
• The score showed acceptable discrimination (AUC 0.673) and good calibration, aligning predicted and observed LNM probabilities.

Conclusions:

• A simple composite pathologic score integrating five adverse features provides a calibrated, clinically interpretable estimate of LNM risk after endoscopic resection of T1 CRC.
• This model translates routine pathology into absolute risk and number-needed-to-surgery, supporting individualized surgical recommendations.