MRI-based assessment and surveillance in watch-and-wait for rectal cancer: a multidisciplinary review

Abstract

Purpose: The management of rectal cancer has evolved toward a paradigm of personalized, multidisciplinary care. The Watch-and-Wait (W&W) strategy has emerged as an organ-preservation alternative for patients achieving a clinical complete response (cCR) after neoadjuvant therapy, aiming to avoid the morbidity and functional impairment associated with total mesorectal excision (TME) while maintaining acceptable oncologic outcomes when applied under structured surveillance.

Methods: This narrative, multidisciplinary review summarizes current evidence on W&W in rectal cancer, with a particular emphasis on radiologic evaluation, practical interpretation strategies, and current areas of uncertainty that are critical for safe clinical implementation.

Results: Although W&W remains debated, accumulating evidence-derived mainly from prospective cohorts, registries, and response-adapted trial populations-supports its oncologic feasibility in carefully selected patients managed in experienced centers under strict surveillance. Magnetic resonance imaging (MRI) plays a central role in both baseline risk stratification and posttreatment response assessment, directly influencing eligibility for organ preservation and early detection of local regrowth.

Conclusion: Diagnostic limitations, interobserver variability, heterogeneity in response definitions, and nonuniform follow-up protocols represent ongoing challenges. Safe implementation of W&W requires careful patient selection, multidisciplinary assessment, standardized MRI technique and reporting, and strict surveillance.

Keywords: Cancer; Magnetic resonance imaging; Neoadjuvant therapy; Rectum; Treatment outcome.