Young-onset colorectal cancer mortality hot and cold spots

"Incidence and mortality of yoCRC, defined as colorectal cancer occurring in individuals under the age of 50, have been steadily increasing since the mid-1990's, but we still do not understand why," said the study's senior author Stephanie Schmit, PhD, MPH, Vice Chair of the Genomic Medicine Institute. "With this study, we aimed to establish where yoCRC mortality rates were higher or lower than expected, known as hot and cold spots, in order to pinpoint regions in the country warranting further investigation and to understand the factors contributing to this increasing burden."

In this study, the researchers utilized colorectal cancer-specific mortality data from 3,036 U.S. counties between 1999 and 2019. The geospatial clustering models were adjusted for yoCRC risk factors and prognostic indicators, including age, sex, race/ethnicity, obesity, smoking, alcohol consumption and socioeconomic conditions. They specifically assessed two broad age-at-diagnosis categories of younger than 50 and older than 50 as well as four stratified categories of younger than 35, 35 to 49, 50 to 64 and older than 65.

Notably, they discovered new mortality hot spots in the Midwest/northeastern Great Lakes region, which constitutes the first reporting of yoCRC mortality hot spots in these areas, in addition to cold spots in western/southwestern counties that have lower risk of yoCRC death. They also found mortality hot spots in southern and Appalachian counties in the younger than 50 category that were consistent with previous studies. However, they determined that hot spots among those ages 35 to 49 more closely followed southern patterns seen in average-onset CRC while hot spots in those younger than age 35 did not, which suggests that deaths among the youngest yoCRC patients may be driven by a distinct set of factors.

"While we recognize that unmeasured factors, such as access to care and related treatment disparities, may be influencing our study results, our findings may initiate new research examining yoCRC mortality-related factors specific to region and age, such as healthcare system accessibility or diet, and provide an impetus to target interventions in particular regions," said R. Blake Buchalter, PhD, MPH, the study's first author.

Dr. Buchalter is a postdoctoral fellow in Dr. Schmit's lab and the lab of Jesse Schold, PhD, in the Department of Quantitative Health Sciences. His fellowship is supported by the Computational Genomic Epidemiology of Cancer (CoGEC) National Cancer Institute-funded T32 Training Program at Case Western Reserve University.