Inclusion and exclusion criteria
tumor, death
NEUROENDOCRINE CARCINOMA, NOS, DISEASES, LARGE CELL NEUROENDOCRINE CARCINOMA, TUMOR, MIXED ADENONEUROENDOCRINE CARCINOMA, CARCINOID TUMOR, SMALL CELL CARCINOMA, NOS, SECONDARY TUMORS, ONCOLOGY, ATYPICAL CARCINOID TUMOR, ENTEROCHROMAFFIN CELL CARCINOID
All the required data was extracted using SEER Stat software (version 8.4.0, SEER ID: 12834-Nov2021). Patients with CRNENs should meet the following criteria: i) NENs pathological type according to the International Classification of Diseases for Oncology, 3rd edition (ICD-O3, 8013/3: Large cell neuroendocrine carcinoma, 8041/3: Small cell carcinoma, NOS, 8240/3: Carcinoid tumor, NOS, 8241/3: Enterochromaffin cell carcinoid, 8244/3: Mixed adenoneuroendocrine carcinoma, 8246/3: Neuroendocrine carcinoma, NOS, 8249/3: Atypical carcinoid tumor). ii) Primary tumor of the colorectal site with the corresponding codes C18.0–C18.9. iii) All patients had stage II-IV that was based on the 7th AJCC staging system from 2010 to 2016 (the 7th AJCC staging system was implemented from 2010 to 2016). iv) Complete and accurate data which included age, sex, race, tumor location, pathological type, grade, the 7th AJCC staging, radiotherapy, surgery, chemotherapy, time of death, last follow-up date, and cause of death. Multiple primary or secondary tumors are excluded. Patients with survival time=0 or not available (NA) were excluded.