Reliability of recording uterine cancer in death certification in France and age-specific proportions of deaths from cervix and corpus uteri.

French uterine cancer recordings in death certificates include 60% of "uterine cancer, Not Otherwise Specified (NOS)"; this hampers the estimation of mortalities from cervix and corpus uteri cancers. The aims of this work were to study the reliability of uterine cancer recordings in death certificates using a case matching with cancer registries and estimate age-specific proportions of deaths from cervix and corpus uteri cancers among all uterine cancer deaths by a statistical approach that uses incidence and survival data. Deaths from uterine cancer between 1989 and 2001 were extracted from the French National database of causes of death and case-to-case matched to women diagnosed with uterine cancer between 1989 and 1997 in 8 cancer registries. Registry data were considered as "gold-standard". Among the 1825 matched deaths, cancer registries recorded 830 cervix and 995 corpus uteri cancers. In death certificates, 5% and 40% of "true" cervix cancers were respectively coded "corpus" and "uterus, NOS" and 5% and 59% of "true" corpus cancers respectively coded "cervix" and "uterus, NOS". Miscoding cervix cancers was more frequent at advanced ages at death and in deaths at home or in small urban areas. Miscoding corpus cancers was more frequent in deaths at home or in small urban areas. From the statistical method, the estimated proportion of deaths from cervix cancer among all uterine cancer deaths was higher than 95% in women aged 30-40 years old but declined to 35% in women older than 70 years. The study clarifies the reason for poor encoding of uterus cancer mortality and refines the estimation of mortalities from cervix and corpus uteri cancers allowing future studies on the efficacy of cervical cancer screening.