Prognosis analysis of 338 rectal neuroendocrine neoplasms with maximum diameter of 1 cm to 2 cm

Objective To analyze the clinical characteristics and prognostic factors of rectal neuroendocrine neoplasm (r-NEN) with the maximum diameter of 1 cm to 2 cm, and to provide a theoretical evidence for selection of resection method. Methods From 1988 to 2015, the data of patients pathologically diagnosed as r-NEN with the maximum diameter less than 2 cm were selected from American surveillance, epidemiology, and end results (SEER) database with SEER* Stat 8.3.5 software. According to the resection method, the patients were divided into local resection group and radical resection group. T test and chi-square test were performed to compare the clinicopathological features. Kaplan-Meier survival analysis and Cox multivariate analysis were used to analyze the prognostic factors analysis. Results The maximum diameter of tumors of 1 831 patients with r-NEN was less than 1 cm, and that of 338 patients with r-NEN was between 1 cm and 2 cm. There were significant differences between two groups in tumor grade, tumor stage, T stage, lymph node metastasis, distant metastasis and resection method (χ2=7.120, 144.728, 86.296, 133.096, 42. 842 and 52.048, all P<0.05). The prognosis of the former was better than that of the latter (χ2=11.590, P=0.001). Among the patients with r-NEN with the maximum diameter of 1 cm to 2 cm, 279 (82.5%) patients received local resection and 59(17.5%) patients underwent radical surgery. Propensity score matching was used to pair the r-NEN patients with the maximum diameter of 1 cm to 2 cm who received different resection methods, and 41 pairs of cases were enrolled. The results of univariate analysis showed that age and tumor grade affected the survival prognosis of patients with r-NEN of the maximum diameter of 1 cm to 2 cm (χ2=6.837 and 10.852, P=0.009 and 0.004). The results of Cox multivariate analysis indicated that age was an independent prognostic factor of patients with r-NEN of the maximum diameter of 1 cm to 2 cm (hazard ratio (HR)=1.110, 95% confidence interval (CI) 1.040 to 1.184, P=0.002). Analysis of subgroups without lymph nodes or distant metastases demonstrated that age (HR=1.101, 95%CI 1.042 to 1.162, P=0.001) and resection method (HR=3.128, 95%CI 1.003 to 9.754, P=0.049) were the independent factors. Conclusions Age is an independent factor of patients with r-NEN of the maximum diameter of 1 cm to 2 cm. Among the patients without lymph nodes or distant metastasis the younger cases and those with local resection have better prognosis. Key words: Prognosis; Rectal neuroendocrine neoplasm; Tumor diameter; Local excision; Radical surgery