Anti-inflammatory Diet Before Diagnosis and Survival After Urologic Cancer: Findings from Two Swedish Prospective...

Dietary patterns with anti-inflammatory properties have been linked to lower risks of several chronic diseases and some cancers, but their impact on survival after cancer is less well understood.

We assessed whether a higher prediagnostic Anti-Inflammatory Diet Index (AIDI) score was associated with all-cause mortality after urologic cancer diagnosis, with urologic cancer-specific mortality evaluated as a secondary end point.

In the Cohort of Swedish Men and the Swedish Mammography Cohort, incident urologic cancers and deaths were identified through Swedish registers. AIDI was derived from food-frequency questionnaires (1997; 2009 in a subset) and defined as the assessment at least 2 yr before diagnosis, preferentially 2009 when available. Follow-up ran from diagnosis to death, emigration, or December 31, 2020.

Cox models estimated hazard ratios (HRs) per 1 standard deviation (SD) higher AIDI, adjusting for demographic factors, lifestyle, comorbidities, and total energy intake. Fine-Gray models assessed urologic cancer-specific mortality while accounting for death from other causes as a competing event.

Among 7686 patients with valid AIDI, 6609 had complete covariate data, including 4990 patients with prostate cancer. During follow-up, 3281 deaths occurred, including 1435 urologic cancer deaths. Each 1-SD higher AIDI was associated with lower all-cause mortality (HR = 0.91, 95% confidence interval [CI] = 0.88-0.95). Evidence for an association with urologic cancer-specific mortality was weak and borderline in cause-specific Cox models (HR = 0.95, 95% CI = 0.90-1.00) and was attenuated in competing-risk analysis (subdistribution HR = 0.97, 95% CI = 0.92-1.02).

Higher prediagnostic AIDI was associated with lower all-cause mortality after urologic cancer diagnosis. Whether this reflects a causal effect of diet or residual confounding, healthy-lifestyle clustering, health care engagement bias, or differences in competing noncancer mortality requires further study.