The Association between the Energy-adjusted Dietary Inflammatory Index and the Risk of Colorectal Cancer in The Norwegian Women and Cancer Study (NOWAC)

Abstract

Background: Colorectal cancer (CRC) is one of the most common cancer types and a leading cause of cancer death worldwide. Norwegian women had the highest incidence rate in 2020 compared to women in other countries. Existing evidence suggests that the dietary inflammatory potential is associated with the risk of CRC and that the risk may vary by anatomical subsite. However, the findings are inconsistent and need further investigation.

Aim: This thesis aimed to assess the association between the inflammatory potential of the diet, measured by energy-adjusted DII (E-DII), and the risk of CRC and cancer by anatomical subsite of the colon and rectum.

Methods: Data from a subsample of 37,226 women in the Norwegian Women and Cancer study (NOWAC) was utilized. E-DII scores were computed based on a food frequency questionnaire completed by the participants at baseline. Cox proportional hazards regression was used to assess associations between quartiles of the E-DII and the risk of CRC and cancer by anatomical subsite.

Results: No significant associations were observed. The most positive association was seen between women in the highest (most pro-inflammatory) E-DII quartile and the risk of proximal colon cancer (age-adjusted HRQ4-Q1: 1.27; 95% CI: 0.91–1.77; multivariable-adjusted HRQ4-Q1: 1.21; 95% CI: 0.86–1.69).

Conclusion: The E-DII was not associated with the risk of CRC or cancer by anatomical subsite. There was a tendency towards a positive relationship between a more pro-inflammatory diet and an increased risk of proximal colon cancer.