Clinicopathological features and prognostic factors of colorectal neuroendocrine neoplasms.

Abstract

572 Background: Limited research is available regarding colorectal neuroendocrine neoplasms (NENs), especially in China. The prognostic factors of colorectal NENs remain controversial. Methods: A total of 68 patients with colorectal NENs were studied retrospectively. Clinical characteristics and prognosis between colonic and rectal NENs were compared. The Kaplan-Meier method and Cox regression models were used to evaluate the capacity of various factors to predict the outcome. Results: Of 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 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, neuroendocrine carcinomas and mixed adenoendocrine carcinomaswere 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 pathological classification ( P= 0.012) were independent prognostic factors. Conclusions: Significant differences in clinicopathological feature and outcome exist between colonic and rectal NENs. Multivariate analysis indicated that tumor size and pathological 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.