UC Davis

Background

Colorectal cancer (CRC) incidence among persons older than 50 years has decreased in California and nationally, but incidence rates have increased among persons younger than 50 years. Previous studies present incidence rates among younger persons using a wide age group of 20-49 years. However, previous population-based studies did not analyze CRC incidence in subgroups defined by age, sex, race/ethnicity, and stage at diagnosis to better understand incidence trends among younger persons.

Methods/approach

We identified all people diagnosed with CRC at the age of 20-49 years from the California Cancer Registry (n = 39,298; 1988-2017). We used SEER*Stat and Joinpoint software to calculate average annual percentage changes (AAPCs) in incidence rates by age at diagnosis, sex, race/ethnicity, and stage. Age was divided into 10-year intervals (20-29, 30-39, and 40-49 years), stage was categorized as early- and late-stage, and race/ethnicity as non-Hispanic White, non-Hispanic Black, Hispanic, Asian/Pacific Islander, and American Indian groups.

Results

Statistically significant increases in early-stage CRC incidence rates were observed among the 20-29, 30-39, and 40-49-year age groups in male and female non-Hispanic White populations (AAPC, 6.3%, 3.3%, and 1.9%, respectively) and Hispanic populations (AAPC, 4.9%, 3.5%, and 2.3%, respectively). Statistically significant increases in late-stage CRC incidence rates were observed among all 3 age groups of male and female non-Hispanic White people (AAPC, 2.8%, 3.1%, and 1.7%, respectively) and Hispanic females (AAPC, 4.2%, 2.3%, and 1.1%, respectively). Statistically significant increases in late-stage CRC incidence rates were also seen in the 30-39 and 40-49-year age groups among non-Hispanic White females (AAPC, 3.4% and 1.8%, respectively), Hispanic males (AAPC, 3.6% and 1.6%, respectively), and Asian/Pacific Islander females (AAPC, 1.9% and 0.7%, respectively). Statistically significant increases in late-stage CRC incidence were observed among 40-to 49-year-old Asian/Pacific Islander males (AAPC, 1.4%) and American Indian males and females (AAPC, 5.5%).

Conclusion

CRC is increasing among several young age groups. Because evidence suggests that younger adults present with more advanced disease, these results may be useful for educating health care providers about CRC risk and suggest that CRC screening recommendations should be developed for this population. Continued surveillance of CRC incidence rates among young adults is warranted.