Patriti A, Graziano F, Chiari R. Mucinous rectal adenocarcinoma and neoadjuvant therapy: Implications for surgical practice. World J Gastrointest Surg 2026; 18(5): 115825 [DOI: 10.4240/wjgs.v18.i5.115825]
Corresponding Author of This Article
Alberto Patriti, MD, PhD, Department of Surgery, Division of General and Robotic Surgery, Azienda Sanitaria Territoriale di Pesaro-Urbino, Ospedale San Salvatore Piazzale Cinelli, 1, Pesaro 61121, Italy. albertopatriti@gmail.com
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Surgery
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review-article
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Patriti A, Graziano F, Chiari R. Mucinous rectal adenocarcinoma and neoadjuvant therapy: Implications for surgical practice. World J Gastrointest Surg 2026; 18(5): 115825 [DOI: 10.4240/wjgs.v18.i5.115825]
World J Gastrointest Surg. May 27, 2026; 18(5): 115825 Published online May 27, 2026. doi: 10.4240/wjgs.v18.i5.115825
Mucinous rectal adenocarcinoma and neoadjuvant therapy: Implications for surgical practice
Alberto Patriti, Francesco Graziano, Rita Chiari
Alberto Patriti, Department of Surgery, Division of General and Robotic Surgery, Azienda Sanitaria Territoriale di Pesaro-Urbino, Pesaro 61121, Italy
Francesco Graziano, Rita Chiari, Department of Medicine, Division of Medical Oncology, Azienda Sanitaria Territoriale di Pesaro-Urbino, Pesaro 61121, Italy
Author contributions: Patriti A contributed to conceptualization, study design, data interpretation, manuscript drafting, and critical revision for important intellectual content; Graziano F and Chiari R contributed to the literature search and selection according to the Scale for the Assessment of Narrative Review Articles criteria; Graziano F contributed to language review and manuscript refinement; Chiari R contributed to the evaluation of oncologic aspects and manuscript editing; All authors participated in the selection and appraisal of the literature based on the Scale for the Assessment of Narrative Review Articles methodologic framework, approved the final version of the manuscript, and agreed to be accountable for all aspects of the work.
AI contribution statement: AI tools (Grammarly and ChatGPT) were used solely for linguistic refinement and formatting assistance. No AI tool was involved in the generation of research data, interpretation of results, or formulation of conclusions. All AI-generated outputs were critically reviewed and revised by the authors.
Conflict-of-interest statement: All authors report no relevant conflicts of interest for this article.
Corresponding author: Alberto Patriti, MD, PhD, Department of Surgery, Division of General and Robotic Surgery, Azienda Sanitaria Territoriale di Pesaro-Urbino, Ospedale San Salvatore Piazzale Cinelli, 1, Pesaro 61121, Italy. albertopatriti@gmail.com
Received: October 27, 2025 Revised: November 19, 2025 Accepted: February 14, 2026 Published online: May 27, 2026 Processing time: 213 Days and 5.8 Hours
Abstract
Mucinous adenocarcinoma (MAC) of the rectum is characterized by ≥ 50% extracellular mucin, constitutes 5%-20% of rectal cancers, and exhibits distinct biological and clinical behaviors compared to non-MAC. Accumulating evidence indicates that MAC may cause reduced responsiveness to standard chemoradiotherapy with notably lower rates of pathologic complete response and tumor downstaging. Meta-analyses report an odds ratio of 0.38 for pathologic complete response in MAC relative to non-MAC. In recent years total neoadjuvant therapy (TNT) has emerged as the preferred preoperative approach for locally advanced rectal cancer, integrating systemic chemotherapy and chemoradiation before surgical intervention. Likely, TNT may be insufficient to fully overcome MAC resistance, but conclusive data are lacking. MAC tumors tend to be larger, possess poorly defined planes, increase the risk of circumferential resection margin positivity, and are infrequently suitable for organ-preserving strategies such as watch-and-wait. All these aspects have direct implications for surgical practice. This review consolidated current evidence concerning the response of MAC to TNT, delineated surgical challenges, and emphasized priorities for multidisciplinary care and research.
Core Tip: Mucinous adenocarcinoma (MAC) is a distinct histologic subtype characterized by abundant extracellular mucin and a reduced response to neoadjuvant chemoradiotherapy or total neoadjuvant therapy. This review integrated molecular, radiologic, and surgical evidence to explain why MAC behaves differently and how meticulous total mesorectal excision can mitigate these challenges. When tumor downstaging and complete (R0) resection are achieved after total neoadjuvant therapy, long-term outcomes may be comparable to non-MAC, underscoring the importance of surgical precision and multidisciplinary planning.
