Lijun Shen, Miao Mo, Leon Jia, Huixun Jia, Qingguo Li, Lei Liang, Debing Shi, Zhen Zhang, Sanjun Cai, Xinxiang Li, Ji Zhu

To investigate the association of age and sex on survival in non-metastatic colorectal cancer (CRC) patients and to identify groups at high risk for poor outcomes. We performed a retrospective analysis of 5,047 non-metastatic CRC patients from 2008 to 2013. Data regarding age at diagnosis; gender; tumor site; tumor stage; differentiation; lymphatic, neural or vascular invasion; and survival outcomes were collected. Patients were stratified into 10-year age groups (≤35, 36-45, 46-55, 56-65, 66-75, >75) and then further analyzed in three age groups (≤35, 36-75, >75). Disease-free survival (DFS) and overall survival (OS) were evaluated using univariate and multivariate Cox regression models. Of the 5,047 eligible patients, 41.3% were female. The tumor stages were balanced between the genders. In the female patients, the tumor stages were similarly distributed among the different age groups, while younger male patients were diagnosed with more advanced disease (P<0.001 for trend). When stratified into three age groups, young females experienced significantly poorer survival than young males (DFS: hazard ratio [HR]=1.85 [1.04-3.30], OS: HR=2.65 [1.11-6.34]). After adjusting for tumor stage, site, differentiated grade and lymphatic or vascular invasion status, females ≤35 and >75 had shorter DFS than patients between 36 and 75 years old (HR=1.57 [1.03-2.38] and HR=1.51 [1.11-2.05, respectively]), while there was no difference in DFS between females ≤35 and those >75. For male patients, older age was associated with poorer OS after the same adjustment. Young female CRC patients (≤35 years old) had the poorest DFS and quite poor OS compared to the other age groups. This emphasizes the need for health care providers to have a heightened awareness and to conduct further research when caring for young female CRC patients.