Association between the dietary inflammatory index and all-cause mortality in colorectal cancer long-term survivors

Pro-inflammatory dietary factors have been shown to be associated with the incidence of a range of cancers. However, there are many fewer studies on the association between the inflammatory potential of diet and survival after cancer diagnosis. We examined the association between post-diagnosis dietary inflammatory index (DII (R)) scores and all-cause mortality in long-term survivors of colorectal cancer (CRC). DII scores were calculated from dietary data of 1,404 CRC survivors collected at a median of 6 years after CRC diagnosis. Using multivariable-adjusted Cox proportional hazards regression models, hazard ratios (HR) and 95% confidence intervals (CI) were estimated for the association of DII scores, modeled continuous and in quartiles, with all-cause mortality. After a median follow-up time of 7 years (after dietary assessment), 204 study participants had died. Overall, in the fully adjusted model there was a suggestion of a positive association between DII score and all-cause mortality (HRDIIquartile4vs1: 1.36; 95% CI: 0.88-2.09 and HRDIIcontinuous: 1.08; 95% CI: 0.97-1.20). However, in subgroup analyses, we found significant differences in individuals with metastatic disease (HRDIIcontinuous: 1.34; 95% CI: 1.07-1.67) and the absence of stoma (HRDIIcontinuous: 1.15; 95% CI: 1.02-1.29). Overall, the post-diagnosis DII was not statistically significantly associated with all-cause mortality in CRC long-term survivors; however, there was suggestive evidence of an association in select subgroups.