Date of this Version
JAMA Oncol. 2017 July 01; 3(7): 921–927. doi:10.1001/jamaoncol.2016.6374.
Importance—Fusobacterium nucleatum appears to play a role in colorectal carcinogenesis through suppression of host immune response to tumor. Evidence also suggests that diet influences intestinal F. nucleatum. However, the role of F. nucleatum in mediating the relationship between diet and the risk of colorectal cancer is unknown.
Objective—To test the hypothesis that the associations of prudent diets (rich in whole grains and dietary fiber) and Western diets (rich in red and processed meat, refined grains, and desserts) with colorectal cancer risk may differ according to the presence of F. nucleatum in tumor tissue.
Design—Prospective cohort study.
Setting—The Nurses’ Health Study (1980–2012) and the Health Professionals Follow-up Study (1986–2012).
Participants—121,700 US female nurses and 51,529 US male health professionals aged 30 to 55 years and 40 to 75 years, respectively, at enrollment.
Exposures—Prudent and Western dietary patterns.
Main Outcomes and Measures—Incidence of colorectal carcinoma subclassified by F. nucleatum status in tumor tissue, determined by quantitative polymerase chain reaction.
Results—We documented 1,019 incident colon and rectal cancer cases with available F. nucleatum data among predominantly white 137,217 individuals over 26–32 years of follow-up encompassing 3,643,562 person-years. The association of prudent diet with colorectal cancer significantly differed by tissue F. nucleatum status (Pheterogeneity = .01). Prudent diet score was associated with a lower risk of F. nucleatum-positive cancers [Ptrend = .003; multivariable hazard ratio of 0.43 (95% confidence interval 0.25–0.72) for the highest vs. the lowest prudent score quartile], but not with F. nucleatum-negative cancers (Ptrend = .47). Dietary component analyses suggested possible differential associations for the cancer subgroups according to intakes of dietary fiber (Pheterogeneity = .02). There was no significant heterogeneity between the subgroups according to Western dietary pattern scores (Pheterogeneity = .23).
Conclusions and Relevance—Prudent diets rich in whole grains and dietary fiber are associated with a lower risk for F. nucleatum-positive colorectal cancer but not F. nucleatum-negative cancer, supporting a potential role for intestinal microbiota in mediating the association between diet and colorectal neoplasms.