Sex differences in muscle-invasive bladder cancers: A study of a French regional population

Although men have a higher risk of developing a bladder cancer, women appear to have a poorer prognosis and a more advanced stage at diagnosis. We performed a retrospective population-based study on muscle invasive bladder cancer (MIBC) using data from a cancer registry in a French department to compare overall and specific survival data according to sex. We included all patients living in the department of Hérault and diagnosed with MIBC between January 1, 2017 and December 12, 2019. Univariable and multivariable analyses were performed on all variables of interest. We included 124 women and 432 men. There was no significant difference in age or stage at diagnosis according to sex. Squamous cell carcinomas were more common in women (P<0.001). Cystectomy was more frequent in men than in women (50.7% vs 35.4%) (P=0.0039). By multivariable analysis, the independent factors for being treated by cystectomy were sex (P=0.004), age (P<0.001) and stage (P<0.001). Forty-seven percent of women received no treatment or palliative treatment. Overall mortality was 79% in women and 63.2% in men (P<0.001). The median specific survival was 10.8months in women and 32.7months in men (P<0.0001). By multivariable analysis, the independent risk factors for mortality were female sex (P=0.047), cT4 stage (P=0.005) and absence of cystectomy (P<0.001). Our study shows that women are less often treated with cystectomy and have worse prognosis than men. The reasons for this gender difference are multifactorial. C.