Fig. 1

Flow chart of patients in this study. The final study population consisted of 226 patients with brain metastasis (BM) from colorectal cancer (CRC) treated at the National Cancer Center Hospital (NCCH) from 1985 to 2017. The training cohort consisted of 112 consecutive patients, accounting for 1.0% of all patients with CRC. The validation cohort consisted of 114 patients with brain metastases who were treated for primary CRC at other institutions in 1987–2017 and referred to our hospital to treat BM from CRC.