Correcting uterine cancer mortality in Estonia using linkage of causes of death and cancer registry data, 2000–2021
Cervical and corpus uteri cancer mortality may be underestimated due to a proportion of deaths attributed to unspecified uterine cancer. The aim was to estimate corrected mortality rates and trends for cervical and corpus uteri cancer in Estonia after reallocation of underlying cause of death using individual linkage of death records and cancer registry records. Deaths in Estonian female population in 2000-2021 with the underlying cause of cervical cancer (ICD-10 code C53), corpus uteri cancer (C54) or cancer of uterus not otherwise specified (C55) were individually linked to Estonian Cancer Registry to identify any cancers diagnosed in these persons. Underlying cause of death was reallocated if applicable. Original and corrected age-standardized (world) mortality trends were modelled using joinpoint regression. During 2000-2021, the corrected number of deaths was 1409 cervical cancer deaths (originally 1388, 1.5 % increase), 1146 corpus uteri cancer deaths (902, 27 % increase), and 50 unspecified uterine cancer deaths (368, 86 % decrease). Proportion of unspecified deaths decreased from 26 % (2000-2004) to 4 % (2016-2021) (p < 0.001). After correction, cervical cancer mortality trend steepened slightly from 0.8 % decrease per year to 1.1 % decrease (both significant). Corpus uteri cancer mortality trend changed direction from significant increase of 1.9 % per year to significant decrease of 1.4 % per year. Routine linkage of causes of death records with cancer registry is warranted for validating underlying cause of death. The results emphasize the importance of the availability of medical documentation for physicians assigning cause of death as well as relevant training.