Clinicopathological Features And Prognostic Factors Of Colorectal Neuroendocrine Neoplasms

ObjectiveNENs are a group of fairly rare tumors whose incidence is keeping increased. Limited research is available regarding colorectal neuroendocrine neoplasms (NENs), especially in China. The objective of our research was to explore the clinicopathological features and prognostic factors of colorectal NENs.Materials and MethodsA total of 68 patients with colorectal NENs were studied retrospectively, all of which were registered in The Second Affiliated Hospital, Zhejiang University School of Medicine and confirmed by pathology. Information such as clinical symptoms, pathology, treatment and outcome were collected. The cohorts were divided into colonic NENs and rectal NENs according to primary site. Clinical characteristics and prognosis between colonic and rectal NENs were compared. The univariate and multivariate analysis method were used to evaluate the capacity of various factors to predict the outcome.ResultsOf the 68 colorectal NENs patients,43 (63.2%) had rectal NENs, and 25 (36.8%) had colonic NENs. Compared with rectal NENs, colonic NENs more frequently exhibited with larger tumor size (P<0.0001) and distant metastasis (P<0.0001).Colonic NENs had a worse prognosis (P=0.027), with 5-year overall survival rates of 66.7% vs. 88.1% compared with rectal NENs. Neuroendocrine tumors (NETs), neuroendocrine carcinomas (NECs) and mixed adenoendocrine carcinomas (MANECs) were noted in 61.8%,23.5% and 14.7% of patients, respectively. According to the available data (n=49), Ki-67 index values were≤2% in 27(39.7%) patients, ranged from 3% to 20% in 6 patients (8.8%) and were>20% in 16 patients (23.5%). Multivariate analyses revealed that tumor location was not an independent prognostic factor (P=0.081), but tumor size (P=0.037) and tumor classification (P=0.012) were independent prognostic factors.ConclusionSignificant differences in clinicopathological features and outcome exist between colonic and rectal NENs. Multivariate analysis indicated that tumor size and tumor classification were associated with the prognosis. However, tumor location was not an independent factor. The worse outcome of colonic NENs observed in clinical practice might be due not only to the biological differences, but also to larger tumor size in colonic NENs caused by the delayed diagnosis.