Management of MANEC of the colon and rectum: A comprehensive review of the literature

Abstract

Mixed adeno-neuroendocrine carcinoma (MANEC) is a rare pathological diagnosis recently acknowledged by the World Health Organization in 2010. MANEC is a neoplasm characterized by significant histological heterogeneity and is characterized by the simultaneous presence of both adenocarcinomatous and neuroendocrine differentiation; their definition includes each component found in at least 30% of the tumor. Colorectal MANEC constitutes an uncommon type of malignant tumor. The true prevalence of colorectal MANEC has not been precisely defined and published studies are limited to case reports and small case series. The aim of the present review was to accumulate the existing evidence on colorectal MANEC with special attention to the clinicopathological characteristics, management and survival rates of patients diagnosed with this malignancy. A total of 20 studies (16 case reports and 4 retrospective cohorts) reported outcomes for patients with colorectal MANEC and were finally considered eligible for analysis. The results of the present study show that patients with early stage MANEC have more favorable survival compared to those diagnosed in advanced stages. Due to its neuroendocrine nature, which is characterized by rapid progression, MANEC is diagnosed in advanced stages in the majority of cases and thus potentially explains the poor survival rates. Because of its aggressive nature and high recurrence rate, adjuvant chemotherapy constitutes a critical part of the treatment and significantly improves survival. Further larger studies are needed in order to establish guidelines for the treatment of these rare lesions.

Colorectal neuroendocrine carcinoma: A case report and review of the literature

“…Moreover, these tumors could be detected at advanced stage[3]. The 3-year overall survival (OS) was estimated to be 5%–27%[1,4,5], and response to chemotherapy was reported as the only predictive factor in patients with metastasis[1]. Because of its aggressive nature and high recurrence rate of the NEC, adjuvant chemotherapy constitutes a critical part of the treatment and significantly improves survival[4].…”

Mixed Adenoneuroendocrine Carcinoma (MANEC) of the Gallbladder: A Systematic Review of Outcomes Following Surgical Management

“…Meanwhile, others support the hypothesis of both morphologically distinctive carcinomas arising from a common, multipotent stem or progenitor cell (16). As far as the histology of these rare tumors is concerned, interesting findings have been observed (8,29). Features of ordinary adenocarcinoma are usually recognized in the tumor surface, the neuroendocrine component has been recognized in areas of vascular and perineural infiltration, while neuroendocrine components were prominent in lymph node involvement cases (29).…”

“…It is acknowledged that long-term outcomes in these patients are largely dependent on the most aggressive component (adenocarcinoma/NEC) of their tumor (8,31,32). Long-term outcomes for patients with gallbladder neuroendocrine tumors have been shown to vary highly possibly due to their divergent disease stage and differentiation degree; 5-year survival rates range from approximately 37% to 60% (17,33) whereas the addition of the adenocarinomatous component is thought to dictate worse prognosis.…”

“…MANECs most commonly arise in the colon, appendix, rectum or stomach (8)(9)(10)(11), however a limited number of MANECs have been reported to originate from the bile duct, the pancreas and the gallbladder (12)(13)(14).…”

Diagnosis of Mixed Adenoneuroendocrine Carcinoma (MANEC) after Neoadjuvant Chemotherapy for Pancreatic and Gastric Adenocarcinoma: Two Case Reports and a Review of the Literature

“…In contrast, the latest and largest Western study reported very poor survival rates of localized gastric MANEC [35]. In some studies of colorectal carcinomas, a poorer prognosis was observed in patients with tumors that harbored chromogranin-positive cells [36, 37, 38, 39], but in other studies, this outcome was not confirmed [40, 41, 42, 43, 44]. Currently, there is no consensus regarding the prognostic significance of NE cells after neoadjuvant chemotherapy, and more studies are needed.…”