Lower Utilization of Colorectal Cancer Screening Among Vegetarians, Adventist Health Study-2

This study aims to examine lifestyle predictors of the utilization of colorectal cancer screening. Using modified Poisson regression, we studied self-reported colorectal cancer screening utilization (colonoscopy or fecal occult blood test) with various dietary and lifestyle characteristics among 33,922 subjects aged 51 + years in the Adventist Health Study-2, a large population-based prospective cohort study. According to the multivariable-adjusted models, vegetarians were less likely to report screening: vegans, prevalence ratio (PR) = 0.80 (95% confidence interval 0.77-0.83); lacto-ovo-vegetarians (0.95 [0.93-0.97]); and semi-vegetarians (0.97 [0.94-0.99]) compared to non-vegetarians. Blacks were more likely than non-Blacks to be screened (1.04 [1.02-1.06]) and males were less likely (0.93 [0.92-0.95]) to utilize the screening tests. Older subjects were more likely to be screened, and unmarried and divorced/widowed subjects were less likely to screen. Education, personal income, and BMI were positively associated with screening, with p-value for trend < 0.001 for all three variables. A family history of colorectal cancer was associated with higher screening prevalence (1.15 [1.12-1.17]). Our stratified analyses on race and gender with dietary patterns showed non-Hispanic White vegans (PR = 0.77 [0.74-0.81]) and male vegans (PR = 0.76 [0.72-0.81]) were least likely compliant with colorectal cancer screening (p = 0.009 and p = 0.04, respectively). Vegans may believe that their personal risk for colorectal cancer is low due to their healthy lifestyle, resulting in lack of compliance to colorectal cancer screening. It remains to be seen whether vegans in AHS-2 also experience higher incidence of colorectal cancer or are diagnosed at a later stage.