Sex difference in presentation and outcomes of bladder cancer: biological reality or statistical fluke?

ABSTRACT

PURPOSE OF REVIEW The impact of sex on the prognosis of patients with muscle-invasive bladder cancer (MIBC) is discussed. Reasons for the presumably worse prognosis in female patients may be anatomical differences, different time delays from first symptoms to diagnosis and variations in hormone receptors and tumour biology. This review summarizes literature on this topic published during the period 2012-2015. RECENT FINDINGS: Methodological quality of most available studies analysing the impact of sex on prognosis of MIBC is limited by their retrospective design or lacking standardization of study parameters. Time delay from first symptoms to diagnosis in women with bladder cancer seems possible, although a prognostic impact of this delay has not been proven yet. Recent cystectomy-series predominantly show comparable tumour stages, although strongest deterioration of prognosis in female patients is described in younger patients and in cases with lymphovascular invasion. No survival difference between sexes was found in studies with rigorous statistics using propensity score matching. Interpretation of studies analysing the prognostic impact of hormone receptors is limited by methodological shortcomings and missing definitions of subsequent signal pathways. SUMMARY: Analyses of population-based cancer-registries demonstrate a comparatively higher cancer-specific mortality for female patients, but the reason for this difference remains unclear. Interaction between sex and oncologic outcome of patients with MIBC seems to be multifactorial, while to date, an independent prognostic impact of sex cannot be proven validly. Research activities in the future should include parameters mentioned above.