Sex Differences in Incidence and Mortality of Bladder and Kidney Cancers: National Estimates from 49 Countries

Objectives: In the United States, among patients diagnosed with bladder cancer (BC), women have increased disease-specific mortality compared with men. The main objective of this study was to determine whether this pattern is also present in other countries. For comparison, similar analyses were performed for kidney cancer (KC).

Methods And Materials: Data for this study were obtained from the GLOBOCAN 2008 database. A total of 49 countries with available information on BC and KC incidence and mortality were included in the analysis, representing all major geographic regions except Africa. For each country, we computed the sex-specific ratio of the total number of deaths from a given cancer to the total number of diagnoses in the year 2008 (the mortality-to-incidence ratio [MIR]). The relative MIR was computed for each country as a ratio of MIR in women to MIR in men. A relative MIR of more than 1 would indicate that the number of cancer-specific deaths relative to the number of cancer-specific diagnoses is greater in women than in men.

Results: For BC, the relative MIRs were significantly more than 1 in 26 countries (53%), significantly less than 1 in 2 countries (4%), and not significantly different from 1 in 21 countries (43%). The median relative MIR was 1.21 (interquartile range: 1.04-1.41). For KC, the relative MIRs were significantly more than 1 in 4 countries (8%), significantly less than 1 in 3 countries (6%), and not significantly different from 1 in 42 countries (86%). The median relative MIR was 1.00 (interquartile range: 0.94-1.06).

Conclusion: Among BC patients, increased disease-specific mortality in women compared with men appears to be a common (although not a universal) phenomenon. This pattern may potentially be explained by differences between the sexes in the biology of disease, time to diagnosis, treatment decisions, and other factors. In contrast, among KC patients, no significant differences in disease-specific mortality were seen between the 2 sexes in the overwhelming majority of the countries.