Study variables and outcomes
DSS, death, AJCC, Cancer
LUNG METASTASIS, SECONDARY, METASTASIS, CANCER
Clinical variables including age, sex, incidence, race, location, histology, grade, TNM stage which were according to the 7th editions of the American Joint Committee on Cancer (AJCC) TNM staging system, metastasis information (i.e bone, brain, liver, and lung metastasis), treatment (i.e. surgery, chemotherapy, and radiation). The primary outcome of this study was OS. OS is defined as the time from diagnosis of CRNENs to death of any cause. The secondary outcome of this study was disease-specific survival (DSS) which was defined as the time from diagnosis of CRNENs to the death specifically caused by CRNENs, while the death due to other cause was deemed as a competing risk.