Patients’ selection
tumor
PRIMARY TUMOR, TUMOR, PRIMARY CANCER
After being granted access to study data files with the reference number 12271-Nov2019, information on patients with newly diagnosed CRC from 2010 to 2015 was taken from the Surveillance, Epidemiology and End Results (SEER) database. The SEER data collection (Overall survival (OS) information was also collected, together with clinicopathological characteristics and pertinent therapy details. The following criteria were met by the patients: (1) patients had to be between the ages of 18 and 75; (2) they had to have stage IV CRC pathologically determined; and (3) CRC was the only primary cancer. Patients with insufficient staging, missing metastatic information, diagnoses made only through autopsy, and patients whose prognosis was unknown were also disqualified. In addition, the tumor size indicated in this study was the primary tumor size.