The Western-style diet is associated with colorectal cancer (CRC) tumors containing higher quantities of Escherichia coli-carrying polyketide synthase (pks) island, according to study results published in Gastroenterology.
For the current study, researchers used 2 prospective US cohort studies, the Nurses’ Health Study and the Health Professionals Follow-up Study. Researchers used a food frequency questionnaire to calculate Western diet score by obtaining data every 4 years during follow-up among 134,775 participants from both cohort studies. Researchers also used quantitative polymerase chain reaction to measure pks+ E coli DNA in 1175 tumors that occurred among 3200 incident CRC cases during follow-up. Inverse probability weighting was integrated into multivariable-adjusted duplication-method Cox proportional hazards regression analyses to adjust for potential selection bias.
The association between CRC and the Western diet score was stronger when tumors contained elevated levels of pks+ E coli (Pheterogeneity =.014). Compared with the lowest tertile of the Western diet score, multivariable-adjusted hazard ratios for the highest tertile were 3.45 (95% CI, 1.53-7.78; Ptrend =.001) for high-level pks+ E coli tumors, 1.22 (95% CI, 0.57-2.63; P =.001) for low-level pks+ E coli tumors, and 1.10 (95% CI, 0.85-1.42; P =.001) for tumors without detectable pks+ E coli. An association was observed between pks+ E coli and lower disease stage, but not between pks+ E coli and tumor location; BRAF, PIK3CA, or KRAS mutations; or microsatellite instability.
Study limitations included potential unmeasured confounding, potential selection bias, the presence of measurement errors, the use of mainly non-Hispanic white cohorts, an inability to establish causality between microbial species and CRC, and the use of observational cohort studies.
The study authors concluded that “the association of Western diet with colorectal cancer incidence is stronger for tumors containing higher amounts of pks+ E. coli. Our findings provide evidence supporting the role of the gut microbiota in mediating the pathogenic link between diet and colorectal cancer.”
Disclosure: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of authors’ disclosures.
Arima K, Zhong R, Ugai T, et al. Western-style diet, pks island-carrying Escherichia coli, and colorectal cancer: analyses from two large prospective cohort studies. Gastroenterology. Published online June 24, 2022. doi:10.1053/j.gastro.2022.06.054
This article originally appeared on Gastroenterology Advisor