Proximal shift of colorectal cancer with increasing age in different ethnicities

Background: 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.

Objective: 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.

Materials and methods: 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.

Results: 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.

Conclusion: Our findings support the premise of etiological and carcinogenic differences based on tumor location and between younger and older patients.