Recalibrating the Genetics and Epidemiology of Colorectal Cancer Consortium Environmental Risk Score for Use in US Veterans.

Background: Risk for colorectal cancer may accumulate through multiple environmental factors. Understanding their effects, along with genetics, age, and family history, could allow improvements in clinical decisions for screening protocols. We aimed to extend the previous work by recalibrating an environmental risk score (e-Score) for colorectal cancer among a sample of US veteran participants of the Million Veteran Program.

Methods: Demographic, lifestyle, and colorectal cancer data from 2011 to 2022 were abstracted from survey responses and health records of 227,504 male Million Veteran Program participants. Weighting for each environmental factor's effect size was recalculated using Veterans Affairs training data to create a recalibrated e-Score. This recalibrated score was compared with the original weighted e-Score in a validation sample of 113,752 (n cases = 590). Nested multiple logistic regression models tested associations between quintiles for recalibrated and original e-Scores. Likelihood ratio tests were used to compare model performance.

Results: Age (P < 0.0001), education (P < 0.0001), diabetes (P < 0.0001), physical activity (P < 0.0001), smoking (P < 0.0001), NSAID use (P < 0.0001), calcium (P = 0.015), folate (P = 0.020), and fruit consumption (P = 0.019) were significantly different between colorectal cancer case and control groups. In the validation sample, the recalibrated e-Score model significantly improved the base model performance (P < 0.001), but the original e-Score model did not (P = 0.07). The recalibrated e-Score model quintile 5 was associated with significantly higher odds for colorectal cancer compared with quintile 1 (Q5 vs. Q1: 1.79; 95% CI, 1.38-2.33).

Conclusions: Multiple environmental factors and the recalibrated e-Score quintiles were significantly associated with colorectal cancer cases.

Impact: A recalibrated, veteran-specific e-Score could be used to help personalize colorectal cancer screening and prevention strategies.