Role of overdiagnosis in the rising incidence of endometrial cancer: a population-based ecological study.
Barmayehvar B., Behzadnia A., Nicholson B., Zahl P-H., Oke J.
OBJECTIVES: Endometrial cancer (EC) incidence has been rising globally, while mortality has remained stable, particularly in Nordic countries. This study aimed to explore the role of transvaginal ultrasound (TVUS) use and overdiagnosis in these trends. METHODS: We analysed crude and age-adjusted EC incidence and mortality rates by stage and age group using data from the Norwegian Cancer and Causes of Death Registries (1970-2019). Annual percentage changes (APC) in early-stage and late-stage cancers were estimated using linear regression. Trends were assessed with the Mann-Kendall test and Theil-Sen estimator. Spearman's correlation evaluated the relationship between regional TVUS billing rates and EC incidence. RESULTS: From 1970 to 2019, age-standardised EC incidence in Norway increased by 79% (16.7-30.0 per 100 000), with a five-yearly growth rate of 7.47% (p=0.020). Mortality remained stable until 2000-2004, with a non-significant drop from 5.0 to 2.75 per 100 000 by 2019 (Sen's slope: -0.20, p=0.15). In postmenopausal women, early-stage incidence rose by 73% (32.1-55.5 per 100 000) and late-stage diagnoses increased by 108% (7.0-14.6 per 100 000). In premenopausal women, early-stage incidence declined by 24% (3.3-2.5 per 100 000), while late-stage diagnoses rose by 189% (0.23-0.66 per 100 000). TVUS use rose from 7.6% to 8.3% annually (2006-2019). The APC in postmenopausal women was similar across stages, with the largest increase in those aged 70+ years. Evidence for TVUS driving early-stage diagnoses was not strong, although a weak correlation between the two was observed in postmenopausal women (r=0.35, p<0.05). CONCLUSIONS: Overdiagnosis and stage migration may explain the rising EC incidence in postmenopausal women. In premenopausal women, overdiagnosis is less likely. TVUS is unlikely to be the main driver of the trends. Further research is needed to clarify the interplay of factors affecting EC trends globally.