Nationwide population-based study of risk of urologic cancers in patients with hospital-diagnosed recurrent cystitis in Denmark

Recurrent infections in the urinary tract may promote urologic cancer through chronic inflammation. A nationwide population-based cohort study investigated the risk of urologic cancers in patients with hospital-diagnosed recurrent cystitis. The study included all Danish adults with a first-time hospital discharge diagnosis of recurrent cystititis during 2006-2022, excluding patients with prior cancer. Among 42,377 patients (68% women, median age 62 years), 1047 were diagnosed with urologic cancer during a median follow-up of 5.7 years. The 1-year risk of any urologic cancer was 1.2% (95% CI 1.1-1.3), with a corresponding standardized incidence ratio of 4.99 (4.56-5.44). Beyond 2 years of follow-up, the SIR remained elevated among women only (1.47; 95% CI 1.20-1.78). The authors conclude that the elevated short-term risk suggests that recurrent cystitis is a clinical marker of urologic cancer. In women, long-term risks for urologic cancer remained elevated.