Advanced rectal lesions: Best practices for assessment and management

Advanced rectal lesions (ARLs), including large laterally spreading lesions (LSLs), villous or high-grade dysplastic adenomas, and early rectal cancers, constitute a critical transitional category between benign adenoma and invasive carcinoma. Historically, radical surgery was liberally employed for these lesions, often resulting in significant morbidity and permanent stoma formation. Contemporary endoscopic and transanal techniques permit curative resection while preserving anorectal function, but careful assessment is mandatory to avoid undertreatment of covert cancers.

We reviewed international guidelines and key studies on ARL assessment and management, focusing on endoscopic imaging, staging modalities and therapeutic techniques. Evidence from ESGE, ASGE, NCCN and BSG/ACPGBI guidelines, prospective trials, and observational cohorts was appraised and summarized. Points of divergence between society guidelines are highlighted where relevant to rectal lesion management.

The rectum has distinct anatomical and vascular characteristics which strongly influence endoscopic and surgical decision making. Lesions in the rectum have a higher risk of submucosal invasive cancer (SMIC) compared to the remainder of the colon andare more likely to be larger, nodular and villous in nature. Rectal surgery is complex and has a higher risk of stoma formation and adverse events than colon surgery. Appropriately selected organ preserving techniques reduce risk and preserve function for patients. High-definition white-light endoscopy with virtual or dyebased chromoendoscopy permits accurate optical diagnosis of ARLs. Assessment of surface features and morphology allows the endoscopist to predict the risk of covert cancer. Routine biopsy is discouraged to avoid fibrosis. Endoscopic ultrasound and pelvic MRI are used selectively for lesions suspicious for deeper invasion or when planning transanal surgery. Endoscopic resection is appropriate for the majority of lesions in the rectum and a selective strategy ensures that the appropriate technique can be chosen to optimize oncological outcomes. Lesions with features of deep invasive cancer should be carefully appraised and discussed in a multidisciplinary setting. Selected lesions with a low risk of covert cancer may be resected by endoscopic mucosal resection (EMR) with margin ablation. Endoscopic submucosal dissection (ESD) provides superior en-bloc and curative resection rates for higher risk lesions. Emerging data demonstrates that ESD has equivalent or superior outcomes compared to transanal endoscopic microsurgery (TEM), or transanal minimally invasive surgery (TAMIS) for larger rectal lesions. Hybrid techniques (e.g., underwater EMR, tip-in EMR, full-thickness resection devices) may also be utilised in the therapeutic framework.

An evidence-based, organ-preserving algorithm for ARLs emphasizes optical risk stratification, individualised technique selection and multidisciplinary input to optimize patient outcomes. Ongoing research will refine hybrid methods, artificial intelligence-aided diagnostics and new organ preserving strategies.