Postdiagnostic Inflammatory, Hyperinsulinemic, and Insulin-Resistant Diets and Lifestyles and the Risk of Prostate Cancer Progression and Mortality.

BACKGROUND

Inflammatory and insulin pathways have been linked to prostate cancer; postdiagnostic behaviors activating these pathways may lead to poor outcomes. The empirical dietary inflammatory pattern (EDIP), empirical dietary index for hyperinsulinemia (EDIH), and empirical dietary index for insulin resistance (EDIR), and associated lifestyle indices (ELIH, ELIR) predict biomarkers of inflammation (EDIP: IL6, TNFaR2, CRP) and insulin secretion (EDIH/ELIH: c-peptide; EDIR/ELIR: TAG:HDL) from whole foods and behaviors.

METHODS

Associations of these indices with time to prostate cancer progression (primary, n = 2,056) and prostate cancer-specific mortality (PCSM; secondary, n = 2,447) were estimated among men diagnosed with nonmetastatic prostate cancer in the Cancer of the Prostate Strategic Urologic Research Endeavor cohort diet and lifestyle sub-study. Because the true (versus clinically documented) date of progression is unobserved, we used parametric (Weibull) survival models to accommodate interval-censoringand estimated adjusted HR and 95% confidence intervals (CI) for prostate cancer progression per 1-SD increase in index. Cox proportional hazards models were used to estimate PCSM associations.

RESULTS

During a median [interquartile range (IQR)] 6.4 years (IQR, 1.3-12.7), 192 progression and 73 PCSM events were observed. Inflammatory (EDIP: HR, 1.27; CI, 1.17-1.37), hyperinsulinemic (EDIH: HR, 1.24; CI, 1.05-1.46. ELIH: HR, 1.34; CI, 1.17-1.54), and insulin-resistant (EDIR: HR, 1.22; CI, 1.00-1.48. ELIR: HR, 1.36; CI, 1.12-1.64) indices were positively associated with risk of prostate cancer progression. There was no evidence of associations between the indices and PCSM.

CONCLUSIONS

Both inflammatory and insulinemic dietary and lifestyle patterns are associated with risk of prostate cancer progression.

IMPACT

For men with prostate cancer, consuming dietary patterns that limit chronic systemic inflammation and insulin hypersecretion may improve survivorship, especially when coupled with active lifestyle and healthy body weight. See related commentary by Kucuk, p. 1673.