The Epidemiology of Colorectal Cancer in Younger and Older Patients.

Background: Recent studies have shown that the incidence of colorectal cancer among younger persons is rising. We investigated incidence trends and survival in the German federal state of North Rhine-Westphalia.

Methods: Cancer registry data from the period 2008-2019 were classified into two age groups (15-54 and 55-99). In each age group, the standardized incidence, average annual percent change (AAPC), and relative 5-year survival (RS) were calculated and stratified according to the site, histology, size, and grade of the colorectal tumor.

Results: 167 919 cases were included, with adenocarcinoma accounting for 86.4%. In 2019, the age-standardized incidence per 100 000 person-years was 13.8 and 10.3 among men and women (respectively) in the younger age group, compared with 197.9 and 126.3 in the older age group. Over the study period from 2008 to 2019, the incidence declined among older men and women (AAPC -2.6% and -2.9%) but remained nearly constant among younger men and women (-0.5% and -0.4%). The incidence of neuroendocrine, T1, and G2 tumors rose in both age groups (AAPC range: 2.3%-12.2%; 2.2%-8.3%, 6.3%-8.8%). Younger patients have a better RS, with the largest difference between age groups being found for neuroendocrine tumors (88% and 83% in younger men and women, 65% and 61% in older men and women).

Conclusion: The incidence of colorectal tumors has remained constant in persons under age 55 and declined in persons aged 55 and older. Nonetheless, the incidence of neuroendocrine tumors and of small and well-differentiated tumors has risen in both age groups. The trends among younger persons and the rise in neuroendocrine tumors merit further study.