Pathological Characteristics, Management, and Prognosis of Rectal Neuroendocrine Tumors: A Retrospective Study from a Tertiary Hospital

Background: Rectal neuroendocrine tumors (rNENs) are rare, constituting 1-2% of rectal tumors, and are often asymptomatic, leading to challenges in early diagnosis. Current management guidelines recommend endoscopic resection for small lesions and surgical intervention for larger or high-risk tumors. This study aims to retrospectively analyze the pathological characteristics, management, and prognosis of rNEN patients.

Methods: Data from the Neuroendocrine Tumor Registry at a tertiary hospital in Milan, Italy from 2005 to 2023 were retrospectively analyzed. Patient demographics, disease characteristics, pathology findings, treatment details, and surveillance data were collected. Statistical analyses included descriptive statistics, multivariable binary logistic regression, and Kaplan-Meier survival analysis.

Results: Forty-five patients were included, 53.3% male with a mean age of 57.5 years. Most patients were asymptomatic, with incidental diagnosis during colonoscopy. Endoscopic excision was the primary treatment modality (77.8%), with surgical resection reserved for incomplete or inappropriate endoscopic resections. Disease progression occurred in 13 patients (28.9%), with tumor-related mortality of 22.2%. Kaplan-Meier analysis showed 5- and 10-year survival rates of 68.8% and 59.1%, respectively, with corresponding progression-free survival rates of 72.8% and 54.0%. Tumor stage was significantly associated with disease progression on multivariable analysis (OR = 7.230, p = 0.039).

Conclusions: This study highlights the heterogeneous presentation and prognosis of rNENs, with a substantial proportion diagnosed incidentally. Endoscopic management was predominantly utilized, aligning with current guidelines for localized tumors. Tumor stage emerged as a significant predictor of disease progression, emphasizing the importance of accurate staging for optimal management. Further research is warranted to refine management protocols and validate these findings.