BACKGROUND

The incidence rates of cervical cancer and the coverage in cervical cancer screening are usually reported by including in the denominator all women from the general population. However, after hysterectomy women are not at risk anymore of developing cervical cancer. Therefore, it makes sense to determine the indicators also for the true at-risk populations. We described the frequency of total hysterectomy in Denmark and its impact on the calculated incidence of cervical cancer and the screening coverage.

MATERIAL AND METHODS

With data from five Danish population-based registries, the incidence rate of cervical cancer and the screening coverage for women aged 23-64 years on 31 December 2010 were calculated with and without adjustments for hysterectomies undertaken for reasons other than cervical cancer. They were calculated as the number of cases divided by 1) the total number of woman-years from the general population; and 2) the at-risk population after exclusion of post-hysterectomy woman-years. Cases were defined as women with cervical cancer (incidence), or as women screened in the recommended interval, with or without adjustment for hysterectomies (coverage).

RESULTS AND CONCLUSIONS

In 2010, the all-age prevalence of hysterectomy was estimated at 6%, and ≥ 16% at age ≥ 65. This translated into an overall 6% increase in the incidence rate of cervical cancer, from 12.8 (unadjusted) to 13.5 (adjusted) per 100,000 woman-years. The screening coverage increased from 76% (unadjusted) to 79% (adjusted). In Denmark, hysterectomies do not have a large overall impact on the calculated cancer incidence and screening coverage. Nevertheless, at ≥ 65 years adjusted rates would increase by almost 20% compared to unadjusted rates. This suggests that calculating disease risks per organ-years may have a role in understanding the true burden of the disease in a population at risk of developing that disease.