NANETS Guidelines for the diagnosis and management of stage I-III rectal neuroendocrine tumors

Well-differentiated rectal neuroendocrine tumors (rNETs) are among the most common NETs and account for approximately 12-27% of all gastrointestinal NETs in North America. Significant discrepancies persist in the management of NETs regarding surveillance strategies, staging modalities, high-risk features, and criteria for surgical intervention. This guideline updates current practices of stage I-III rectal NETs with the utilization of GRADE (Grading of Recommendations, Assessment, Development, and Evaluation) methodology and Delphi method of consensus among leading experts in the North American region. We found that several technological advances, such as 68Ga- or 64Cu-DOTATATE SSTR PET/CT, and broad adoption of pelvic MRI have improved staging of rNETs, along with modified endoscopic mucosal and submucosal resection and full-thickness excision techniques that demonstrate efficacy and safety for resection. Pivotal long-term outcome studies provide insight into i) risk factors for regional lymph node metastasis, ii) the impact of R1 excision (endoscopic), iii) best practices for intermediate-sized rNETs (11-20 mm), and iv) risk in small rNETs (≤10 mm). Recommendations were developed upon evidence-based conclusions from the GRADE review to define the role of baseline staging with MRI, advanced endoscopy, and transanal endoscopic surgical methods appropriate for T1 rNETs, the role of salvage therapy in cases of R1 resection, and the consideration of pathologic variables to direct definitive treatment and surveillance. We conclude that advances in screening programs and imaging allow for improved detection and staging of rNETs, while long-term outcome studies can better direct patients toward evidence-based treatment management and rectal organ preservation through less radical resection methods.