Rectal neuroendocrine tumors in a Latin American population: Insights from a Peruvian national cancer institute

Abstract

BACKGROUND

Well-differentiated rectal neuroendocrine tumors (rNETs) represent approximately 28% of gastrointestinal neuroendocrine tumors, with a rising incidence over recent decades. However, data from Perú remains limited.

AIM

To assess overall survival (OS) in patients with rNETs and describe the clinical and pathological characteristics of the study population.

METHODS

This retrospective study included patients diagnosed with rNETs at the Instituto Nacional de Enfermedades Neoplásicas between 2009 and 2024. Qualitative variables were evaluated using the χ² test through contingency tables. OS was estimated using the Kaplan-Meier method, and differences between groups were assessed with the log-rank test. Cox proportional hazards models were used to evaluate variables associated with OS. All statistical analyses were conducted using R software.

RESULTS

A total of 52 patients were included, with a mean age of 51.9 years (range: 27-74 years) and composed of 65.4% females. The most common stage at diagnosis was stage I (48.1%), followed by stage IV (36.5%). The median OS within the study population was 76 months. The 5-year OS for grade 1 tumors was 92.9% compared to 32.6% for grade 2 tumors (P = 0.00032). The median OS was 48 months for tumors exceeding 20 mm in size, whereas it was not reached for tumors measuring 20 mm or less (P = 0.0056). Similarly, the median OS for patients classified as lymph node involvement 1 was 46 months, while it was estimated at 112 months for those classified as lymph node involvement 0 (P = 0.0063).

CONCLUSION

rNETs exceeding 2 cm in size, classified as grade 2, or presenting with lymph node involvement 1 status were correlated with advanced disease stages and diminished survival outcomes.

Keywords: Rectal neoplasms; Neuroendocrine tumors; Survival analysis; Retrospective studies; Treatment outcome

Core Tip: This retrospective study encompassed the largest known Peruvian patients with well-differentiated rectal neuroendocrine tumors. With a median overall survival of 76 months and a 5-year survival rate of 60.6%, outcomes were significantly affected by tumor size, grade, and nodal status. Grade 2 tumors, lesions > 20 mm, and nodal involvement were linked to poorer survival. These findings provide important regional data and support the integration of these factors into risk-stratification strategies for rectal neuroendocrine tumors in Perú.