Researchers identify higher rates of young-onset CRC mortality in Midwest, Great Lakes regions

Researchers have discovered geographic patterns of mortality rates among patients with young-onset colorectal cancer in the United States, according to findings published in Gastroenterology.

Using CRC-specific mortality data from 3,036 U.S. counties from 1999 to 2019, researchers at the Lerner Research Institute and the Center for Young-Onset Colorectal Cancer at Cleveland Clinic categorized patients by age at diagnosis and adjusted for young-onset CRC risk factors and prognostic indicators. They identified new young-onset CRC mortality hot spots in the Midwest and northeastern Great Lakes region and cold spots in western and southwestern counties, which have a lower risk for young-onset CRC mortality.

In an interview with Healio, Blake Buchalter, PhD, MPH, study author and postdoctoral fellow in the department of quantitative health sciences and Genomic Medicine Institute at Cleveland Clinic Lerner Research Institute, highlighted key takeaways from the study and detailed future research directives.

Healio: What was the main driver behind your team’s decision to explore this topic?

Buchalter: Incidence and mortality of colorectal cancer among those diagnosed under the age of 50 have been rising in the United States since the mid-1990s with poorly understood geographic patterns and causes.

We aimed to build upon and clarify the existing geospatial literature by identifying geographic hot and cold spots showing where young-onset colorectal cancer (yoCRC) mortality is significantly more or less common than expected.

Healio: How was the study designed?

Buchalter: We utilized 1999-2019 CDC WONDER Underlying Cause of Death data and geographic information system spatial clustering methods to retrospectively identify geographic hot and cold spots of yoCRC in U.S. counties. Unlike previous work, we directly adjusted for risk factors and prognostic indicators, such as smoking and obesity, when identifying hot and cold spots and stratified yoCRC into younger (< 35 years) and older (35-49 years) age categories to examine how clustering patterns might differ between these populations.

Healio: What were the main takeaways?

Buchalter: Geographic hot spots of yoCRC mortality among older patients (35-49 years) more closely matched the southern U.S. patterns seen for average-onset CRC, while mortality hot spots among the youngest yoCRC patients (< 35 years) have distinct hot spot patterns in the Midwest and Great Lakes region. There were also vast yoCRC mortality cold spots across the western U.S. for all age categories.

Healio: How will these results inform patient care going forward?

Buchalter: These are aggregated ecological results, so patient care should not be adjusted from these results alone. These findings should serve as a baseline for further in-depth study to both confirm the hot and cold spots we identified and also consider applying more granular patient-level data within the sub-region hot spots we found.

Healio: What additional research is needed?

Buchalter: More descriptive and associative epidemiological work is needed, particularly spatiotemporal studies in order to improve understanding of when and where the rise in yoCRC incidence/mortality began. More research utilizing large cohorts and cancer registry data may help to elucidate the underlying drivers and causes of the rise.

I think it is important to emphasize again that these are findings from county-aggregated data and should be viewed as a starting place for further study. Also, these data are from before the U.S. Preventive Services Task Force changed their recommendations for beginning colorectal cancer screening at 45 years old.

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