Sex-specific bladder cancer incidence trends and generational effects in Spain

This study aimed to assess long-term trends in bladder cancer incidence in Spain from 1992 to 2021, using Age-Period-Cohort (A-P-C) modelling to disentangle the contributions of age, period, and cohort effects.

An ecological trend study was conducted using data from the Global Burden of Disease (GBD) 2021 Study via the Global Health Data Exchange. Age- and sex-specific incidence counts for Spain (1992-2021) were analyzed. Joinpoint regression estimated annual percent changes (APCs) and average annual percent changes (AAPCs). A-P-C modelling assessed net and local drifts, as well as cohort and period rate ratios using 5-year age groups and calendar periods.

From 1992 to 2021, 377,430 male and 66,191 female BC cases were estimated. In men, age-adjusted incidence declined (AAPC = -0.6 %), driven by favourable birth cohort and period effects. In women, a modest decline (AAPC = -0.3%) masked a mid-century cohort effect, with increased risk in those born between 1957 and 1967-consistent with a delayed tobacco epidemic. Incidence rose with age in both sexes, though male-to-female incidence ratios narrowed in older groups.

BC incidence in Spain reflects complex, sex-specific temporal dynamics. While male incidence is decreasing, women show persistent cohort-specific increases. These trends underscore the importance of sex-sensitive public health strategies targeting modifiable risk factors, particularly tobacco use.