Sex Differences in Urothelial Bladder Cancer Survival

While urinary bladder cancer is consistently more common in men worldwide, women have poorer prognosis. The aim of this study was to outline sex differences in prognostic factors and clinical management and to explore whether these can explain the poorer urinary bladder cancer outcome in women.

We performed a population-based cohort study including all patients diagnosed with urothelial bladder cancer between 1997 and 2014 at age 18 to 89 who had data recorded in the Swedish Urinary Bladder Cancer Register (n = 36,344). Female-to-male odds ratios for clinical management parameters were estimated by logistic regression. To quantify sex differences in bladder cancer-specific survival, we estimated empirical survival proportions and mortality rates as well as applied flexible parametric models to estimate female-to-male hazard ratios and survival proportions over follow-up. Adjusted models included age, year, World Health Organization grade, stage, marital status, education, health care region, birth country, and comorbidity.

Except for an adverse stage distribution in women, we found no evidence of unequal clinical management. Among those diagnosed with bladder cancer, women had a higher bladder cancer mortality (adjusted hazard ratio, 1.15; 95% confidence interval, 1.08-1.23) driven by muscle-invasive tumors (adjusted hazard ratio, 1.24; 95% confidence interval, 1.14-1.34). The female survival disadvantage was confined to the first 2 years after diagnosis.

The excess bladder cancer mortality in women is limited to those diagnosed with muscle-invasive tumors and cannot be explained by the examined clinicopathologic factors. Further investigations of sex differences in therapeutic procedures and outcomes, including complications, of muscle-invasive bladder cancer, must be performed.