Dietary patterns affect systemic and local intestinal inflammation, which have been linked to colorectal carcinogenesis.
Chronic inflammation can interfere with the adaptive immune response. We investigated whether the association of a diet that promotes intestinal inflammation with risk of colorectal carcinoma was stronger for tumors with lower lymphocytic reactions than tumors with higher lymphocytic reactions.
Dr Shuji Ogino and colleagues from Massachusetts, USA collected data from the molecular pathological epidemiology databases of 2 prospective cohort studies, including the Nurses’ Health Study (since 1976) and the Health Professionals Follow-Up Study (since 1986).
The researchers used duplication-method time-varying Cox proportional cause-specific hazards regression to assess the association of empirical dietary inflammatory pattern score with colorectal carcinoma subtype.
Foods that contribute to high empirical dietary inflammatory pattern scores include red and processed meats, refined grains, carbonated beverages, and some vegetables.
The team noted that foods that contribute to low empirical dietary inflammatory pattern scores include beer, wine, coffee, tea, yellow and leafy vegetables, and fruit juice.
Colorectal tissue samples were analyzed histologically for patterns of lymphocytic reactions.
During follow-up of 124,433 participants, the researchers documented 1311 incident colon and rectal cancer cases with available tissue data.
The researchers observed that the association between the empirical dietary inflammatory pattern and colorectal cancer risk was significant, and varied with degree of peritumoral lymphocytic reaction.
Higher empirical dietary inflammatory pattern scores were associated with increased risk of colorectal cancer with an absent or low peritumoral lymphocytic reaction, but not risk of tumors with intermediate or high peritumoral lymphocytic reaction.
Dr Ogino's team concludes, "In 2 prospective cohort studies, we associated inflammatory diets with a higher risk of colorectal cancer subtype that contains little or no peritumoral lymphocytic reaction."
"These findings suggest that diet-related inflammation might contribute to development of colorectal cancer, by suppressing the adaptive anti-tumor immune response."