Trends in incidence rates of uterine corpus cancer by birth cohort in 24 countries, 1998-2017.

Background: Increases in uterine corpus cancer incidence have been reported in multiple countries, with age-specific patterns suggesting a possible birth cohort effect. However, most studies rely on period-based approaches, limiting characterization of trends by birth cohort.

Methods: Uterine corpus cancer incidence data for women aged 30-84 from 1998-2017 were obtained from Cancer Incidence in Five Continents Plus, NORDCAN, and the NAACCR databases. Age-period-cohort models were applied to estimate overall and age-specific average annual percent changes, cohort rate ratios (CRRs), and period rate ratios, covering birth cohorts from 1914-1922 through 1979-1987.

Results: From 1998-2017, incidence rates increased in 13 of 24 countries, with the fastest rises in Thailand (3.58% per year; 95%CI, 2.78-4.38), Belarus (3.32%; 3.06-3.57), and Türkiye (3.01%; 2.35-3.67); decreased in Austria (-1.57%; -2.00 to -1.13) and Finland (-0.76%; -1.24 to -0.29); and remained stable in nine. Increases were steepest among women aged 30-34 years, exceeding 5% per year in Thailand and the United Kingdom. Birth cohort effects were detected in 15 countries, including 10 with rising incidence. The model-based CRRs, adjusted for age differences and period deviations, indicated that incidence rates were 3.45-fold higher (95%CI, 2.67-4.46) in women born circa 1983 versus 1953 in the United Kingdom, 3.08-fold higher in Thailand (95%CI, 1.64-5.79), and 3.03-fold higher in Belarus (95%CI, 2.19-4.21).

Conclusion: Birth cohort effects detected in 10 of 13 countries with increasing trends suggest generational shifts in risk may be contributing to rising uterine cancer incidence and underscore the importance of early life exposures.