Cabasag CJ, et al. - Using data from successive volumes of Cancer Incidence in Five Contents, a comprehensive overview of ovarian cancer incidence trends globally, examining the influence of birth cohort and period of diagnosis on changing risk was provided. Northern and eastern European countries, and northern America showed the highest incidence of ovarian cancer. Most countries show declining trends with the exception of a few central and eastern Asian countries. Europe and North America showed marked declines for women aged 50-74, where annual decline in rates up to 2.4% (95% CI: -3.9, -0.9) in Denmark was noted over the last decade. Furthermore, in United States and Denmark, generations born after the 1930s showed declines in the incidence rate ratio (IRR), with an additional strong period effect seen around 2000. In contrast, younger generations born after the 1950s in Japan and Belarus showed increased IRRs. Overall, the increased use of oral contraceptive pills and changes in the prevalence of other reproductive risk and protective factors for ovarian cancer over the years studied may have contributed to the favorable trends in ovarian cancer incidence. The variation in ovarian cancer incidence rates may partly be due to changes in disease classifications and cancer registry practices.