Impact Of Old Age On Resectable Colorectal Cancer Outcomes

Background:With the aging of the population and the extension of life expectancy,the incidence of colorectal cancer in the elderly is increasing.This study was performed to identify a reasonable cutoff age for defining older patients with colorectal cancer(CRC)and to examine whether old age was related with increased colorectal cancer-specific death(CCSD)and poor colorectal cancer-specific survival(CCSS).Methods:76,858 eligible patients from the Surveillance,Epidemiology and End Results(SEER)database were included in this study.The Cox proportional hazards regression model and the Chow test were used to determine a suitable cutoff age for defining the older group.Furthermore,a propensity score matching analysis was performed to adjust for heterogeneity between groups.A competing risk regression model was used to explore the impact of age on CCSD and non-colorectal cancer-specific death(non-CCSD).Kaplan-Meier survival curves were plotted to compare CCSS between groups.And a Cox regression model was used to validate the results.Results:Based on a cutoff age of 70 years,the examined cohort of patients was classified into a younger group(n=51,915,<70 years of old)and an older group(n=24,943,?70 years of old).Compared with younger patients,older patients were more likely to have fewer lymph nodes sampled and were less likely to receive chemotherapy and radiotherapy.When adjusted for other covariates,age-dependent differences of 5-year CCSD and 5-year non-CCSD were significant in the younger and older groups(15.84%and 22.42%,P<0.001;5.21%and 14.21%,P<0.001).And an age of>70 years remained associated with worse CCSS comparing with younger group(SHR,1.51[95%CI,1.45-1.57],P<0.001).The Cox regression model as a sensitivity analysis had a similar result.Conclusion:Seventy is a suitable cutoff age to define those considered as having elderly CRC.Elderly CRC was associated with not only increased non-CCSD but also with increased CCSD.Further research is needed to provide evidence of whether cases of elderly CRC should receive stronger treatment if possible.