Frequency of cervical intraepithelial neoplasia treatment in a well-screened population.

Treatment of cervical intraepithelial neoplasia (CIN) detectable at screening has helped reduce the incidence of cervical cancer, but has also led to overtreatment. The estimates of overtreatment have often focused on a particular grade of CIN or age group. The aim of this paper was to provide a nationwide population-based estimate of the frequency of CIN treatment per prevented cervical cancer case in a well-screened population. We retrieved the data from the Danish National Population, Patient, Health Insurance, Pathology, and Cancer Registers, and calculated annual age-standardized CIN treatment rates. We estimated the frequency of CIN treatment per prevented cervical cancer case by comparing the cumulative life-time risk of CIN treatment from 1996 onward, with the difference in the cumulative life-time risks of cervical cancer in the prescreening and the screening periods. Since 1996, more than 5,000 CIN treatments were undertaken annually in the population of about 2.2 million women aged 15-84 years, and at present 5.2 CIN treatments are undertaken per 1,000 women aged 20-49. About six women have undergone CIN treatment for each prevented cervical cancer. The frequency of CIN treatment increased after 2004 and at present almost eight women are treated per prevented cervical cancer case. Screening, though effective in reducing the incidence of cervical cancer, leads also to a considerable burden of CIN treatment. Future trends in CIN treatment should be closely monitored.