A Comprehensive Review on Recent Advances in Management, Presentation, and Pathophysiology of Rectal Neuroendocrine Tumors View PDF

^*CH Srinaini
Medicine, Kamineni Institute Of Medical Science, Narketpalle, Telangana, India

^*Corresponding Author:

CH Srinaini
Medicine, Kamineni Institute Of Medical Science, Narketpalle, Telangana, India

Published on: 2024-10-16

Abstract

A rectal neuroendocrine neoplasm (r-NEN) is one of the most common digestive NENs, along with a small bowel NEN. Due to the widespread use of endoscopic screening for colorectal cancer and the advanced endoscopic procedures available today, their incidence has increased in the past few years. In view of their low risk of local or distant invasion, well-differentiated r-NENs smaller than 10 mm should be endoscopically removed. Because r-NENs larger than 20 mm may spread distantly and involve the muscularis propria, they should be surgically resected. Metastasis risk is intermediate for tumors between 10 and 20 mm, and endoscopic treatment can be challenging for these tumors. A possible algorithm is proposed here based on the limited and poorly codified indications for surveillance once a patient has been removed.

Keywords

Rectal neuroendocrine tumors, Systemic therapy, Endoscopy

Introduction

In most cases, NEN arise from the intestinal tract. In addition to indolent well-differentiated neuroendocrine tumors (NETs), neuroendocrine carcinomas (NECs) are very aggressive poorly differentiated NETs. It is possible for them to arise from practically any part of the human body [1, 2]. r-NENs represent 12% - 27% of all gastrointestinal NENs, after the small intestine. The proportion of NETs in rectal cancers, however, is 1% - 2%. The surveillance, epidemiology, and end results (SEER) database shows an increasing incidence of r-NENs over the past few years, and this trend was also confirmed by the German registry, as well as Asian register, even though the highest incidence rate (IR) was reported in the United States, where the rate was approximately 1.3 per 100,000 people and increased tenfold between 1970 and 2020 [3]. European IRs were lower than those reported in SEER, with Norway reporting the highest IR and Austria reporting the lowest. The lack of national registries may have caused an underreporting of the disease. As screening colonoscopies have become more popular, the incidence has increased. A polish screening colorectal cancer (CRC) program cohort of 50,148 participants reported a prevalence of r-NENs of between 0.05% and 0.07%, despite limited data on r-NENs diagnosed through CRC screening programs. NENs were identified in the English bowel cancer screening program 29 times for rectal cancer and 18 times for colon cancer, which represents a prevalence of 0.04% [4-7]. In Western countries, endoscopists are still not sufficiently recognizing r-NENs as neuroendocrine lesions, since a recent study revealed that only 18% of NETs were suspected to be neuroendocrine. The clinical significance of suspicion of r-NENs before their resection lies in the fact that it significantly influences how they are treated. It has been reported that patients diagnosed with r-NENs before resection showed a greater rate of complete resection than those whose tumors were resected as polyps before being diagnosed. The application of artificial intelligence to gastrointestinal endoscopy may be able to detect and diagnose r-NENs, thereby resulting in a greater incidence, but also more effective treatments [8-11].