Early Rectal Cancer: Diagnostic Challenges and the Role of Endoscopic Intermuscular Dissection Within the Therapeutic Algorithm

Early rectal cancer represents a challenging setting in which accurate locoregional staging is essential to guide appropriate treatment. Current diagnostic strategies primarily include magnetic resonance imaging (MRI) and endoscopic ultrasound (EUS). However, both modalities show significant limitations in early-stage disease, particularly in T staging. This diagnostic gap impacts therapeutic decision-making, particularly in patients with lesions suggestive of deep submucosal invasion. In these cases, endoscopic submucosal dissection (ESD) may be insufficient to achieve adequate vertical negative margins, whereas radical surgery is associated with considerable morbidity and potential impairment of quality of life. In this gray zone, endoscopic intermuscular dissection (EID) has recently emerged as a novel therapeutic approach designed to overcome the limitations of standard endoscopic resection. By enabling dissection within the deeper intermuscular plane, it can achieve curative resections while preserving rectal wall integrity. This narrative review aims to explore the current diagnostic gaps in early rectal cancer and to define the potential role of EID within the current therapeutic algorithm.