Risk Factors for Lymph Node Metastasis and Survival Outcomes in Colorectal Neuroendocrine Tumors

Objective: The aim of our study was to analyze the factors affecting lymph node metastasis (LNM) and the prognosis of colorectal neuroendocrine tumors (NETs).

Patients and methods: A retrospective analysis was conducted to collect the clinical data of 135 patients with colorectal NETs from January 2000 to December 2018, including clinical manifestations, pathological results, treatment methods, etc. Follow-up was regularly performed to observe the recurrence and metastasis of tumors and to identify the clinical and pathological features of colorectal NETs, risk factors for LNM and survival outcomes.

Results: Among 135 patients, there were 57 (42.2) patients with LNM, and the independent risk factors for LNM in the multivariable analyses were tumor diameter ≥2 cm (P= 0.040) and tumor grade G3 (P=0.001). Patients were followed up for 1 to 190 months, and of the 133 patients who were successfully followed up, the 5-year OS was 71.7%, and the 5-year PFS was 69.0%. The multivariate analysis for survival outcomes showed that age ≥65 years (P=0.002/<0.001) and lymph node metastasis (P=0.018/0.025) were independent risk factors affecting 5-year PFS and OS in colorectal neuroendocrine tumors. Tumors in the colon (P=0.022), moderately positive (++) CgA (P=0.010) and strongly positive (+++) CgA (P=0.007) were independent risk factors for poor 5-year PFS in patients with colorectal NETs.

Conclusion: Rectal NETs have a better prognosis than colonic neuroendocrine tumors. Tumor diameter and tumor grade are independent risk factors for LNM in colorectal neuroendocrine tumors. Age, tumor location, lymph node status and a positive level of the neuroendocrine marker CgA are independent risk factors that affect the prognosis of colorectal NETs.