This deep dive tackles the challenging management of the malignant polyp (early T1 colorectal cancer), focusing on the pivotal decision point: endoscopic cure versus formal surgical resection. We review key precursor lesions (adenomas, sessile serrated lesions or SSLs) and the critical anatomical distinction of invasion beyond the muscularis mucosa.

A major focus is on predicting invasion depth using enhanced endoscopic criteria, including Paris morphology (depressed lesions, e.g., 0-III, are high risk) and advanced imaging patterns (Kudo V/Vn and NICE Type 3 suggest deep invasion). The episode mandates interpreting quantitative pathology, including the critical depth thresholds: less than 1,000 µm for sessile/flat lesions or less than 3,000 µm for pedunculated lesions means negligible metastatic risk.

Crucially, we detail why unfavorable features (Lymphovascular Invasion (LVI), tumor budding, poor differentiation, positive margins) compound risk and often mandate surgery, even if invasion is shallow. We stress the absolute necessity of end-block resection for accurate staging, detailing why piecemeal endoscopic mucosal resection (EMR) compromises pathology and often forces unnecessary colectomy.