Atopic allergic conditions and prostate cancer risk and survival in the Multiethnic Cohort study

BACKGROUND: Previous studies investigating relationship between atopic allergic conditions (AACs)—a highly reactive immune state—and prostate cancer (PCa) risk were inconclusive, and few have studied diverse racial/ethnic populations. METHODS: We analysed 74,714 men aged ≥45 years at enrollment in Multiethnic Cohort study. Using multivariable Cox regression, we estimated hazard ratios (HRs) and 95% confidence intervals (CIs) for self-reported AAC status on PCa outcomes. RESULTS: Through 2017, 8697 incident PCa and 1170 related deaths occurred. Twenty-one percent of men reported a history of AACs. AACs were not associated with incident PCa (HR = 0.98, 95% CI: 0.93–1.03) but were significantly inversely associated with PCa mortality (HR = 0.79, 95% CI: 0.67–0.92). This inverse association was consistently observed across all racial/ethnic groups (HR range: 0.60–0.90). Among men diagnosed with PCa, AACs were inversely associated with PCa-specific death (HR = 0.75, 95% CI: 0.63–0.89). Adjusting for potential confounding effect of PSA screening did not meaningfully change the results. No significant heterogeneity was observed in the effect of AACs on PCa incidence or mortality by Dietary Inflammatory Index. CONCLUSIONS: Hyper-allergic conditions were not associated with PCa incidence but were inversely associated with PCa mortality, suggesting a potential role in reducing tumour progression. Further aetiological research is warranted to understand underlying mechanisms.