Trend of cervical cancer mortality in Belgium (1954-1994): tentative solution for the certification problem of unspecified uterine cancer.

We investigated the evolution of mortality from cervical cancer in Belgium between 1954 and 1994 in terms of absolute number of deaths, and standardised and age-specific mortality rates. Changes over generations were summarised using the standardised cohort mortality ratio. Trend studies of cervical cancer mortality were hampered by certification problems. The number of deaths due to cancer of the uterine cervix is not known exactly since a substantial proportion of death causes are coded as cancer of the uterus without specifying the anatomic site: cervix or corpus uteri. This inaccuracy in codification has been corrected using distribution tables derived from countries where this certification problem is minimal. Trends in mortality from certified and corrected cervical cancers were compared. The corrected age-standardised mortality rate decreased continuously over the last 4 decades, from over 14 to 5 per 100,000 woman-years (slope -0.26/100,000 woman-years, 95% CI -0.28 to -0.24). Its slope is 3.1 times (95% CI 2.9-3.5) more important than for the rate of mortality from certified cervical cancer. In addition to the almost linear decrease, substantial nonlinear cohort influences were observed in certified and corrected mortality rates. The tendency of increasing mortality in women born after 1935 required particular attention. Nevertheless, the slope of the corrected recent cohort effect remained limited in Belgium, probably as a consequence of screening.