Lin Yang, Zhenchong Xiong, Wenzhuo He, Kunqian Xie, Shousheng Liu, Pengfei Kong, Chang Jiang, Guifang Guo, Liangping Xia

Studies have indicated a variation in colon cancer pathology with increased age. More findings have also suggested differences in genetics, biology, and demography in terms of ethnicity. Large-scale studies closely examining tumor location shift with aging and ethnicity are scarce. We compared the tumor location shift with aging and the difference in survival based on tumor location by age group among the African-American, White, and Asian/Pacific Islander patients with colorectal cancer. We collected 270,390 cases from the Surveillance, Epidemiology, and End Results database between 2004 and 2014. Ethnicity distribution between younger (age <70 years) and older (age ≥70 years) patients was analyzed using univariate and multivariate logistic regression. The Kaplan-Meier method was used to compare the tumor location survival difference in the African-American, White, and Asian/Pacific Islander patients. Larger tumors, female sex, M0, advanced N stage, no treatment, moderate to poor differentiation, total number of lymph nodes evaluated >12, and right-sided colon cancer were more common in patients aged ≥70 years. More adverse prognosis was found in younger patients compared to older patients. Tumor location frequency differed based on age; the most pronounced differences were found in White patients. The right-sided colon cancer survival inferiority was present only in White patients. Our findings support the premise of etiological and carcinogenic differences based on tumor location and between younger and older patients.