The predicted effect of changes in cervical screening practice in the UK: results from a modelling study

Abstract

announced that its screening interval would be reduced to 3 years in women aged 25 -49 and fixed at 5 years in those aged 50 -64, and that women under 25 years will no longer be invited for screening. In order to assess these and possible further changes to cervical screening practice in the UK, we constructed a mathematical model of cervical HPV infection, cervical intraepithelial neoplasia and invasive cervical cancer, and of UK age-specific screening coverage rates, screening intervals and treatment efficacy. The predicted cumulative lifetime incidence of invasive cervical cancer in the UK is 1.70% in the absence of screening and 0.77% with pre-2003 screening practice. A reduction in lifetime incidence to 0.63% is predicted following the implementation of the 2003 NHSCSP recommendations, which represents a 63% reduction compared to incidence rates in the UK population if it were unscreened. The model suggests that, after the implementation of the 2003 recommendations, increasing the sensitivity of the screening test regime from its current average value of 56 to 90% would further reduce the cumulative lifetime incidence of invasive cervical cancer to 0.46%. Alternatively, extending screening to women aged 65 -79 years would further reduce the lifetime incidence to 0.56%. Screening women aged 20 -25 years would have minimal impact, with the cumulative lifetime incidence decreasing from 0.63 to 0.61%. In conclusion, the study supports the 2003 recommendations for changes to cervical screening intervals. The implementation of the National Health Service Cervical Screening Programme (NHSCSP) in 1988 resulted in a substantial reduction in the overall incidence of cervical cancer (Quinn et al, 1999). The NHSCSP has invited women aged 20 -64 years for cervical cancer screening every 3 -5 years, depending upon the specific policy of the local Health Authority. In 2003, the NHS announced that women aged 25 -49 years will be invited for screening every 3 years, while those aged 50 -64 should be invited every 5 years. It was also recommended that women under 25 years should no longer be screened. The new screening interval recommendations are based on the estimated duration of the protective effect of screening in different age groups and are the result of an audit of the screening histories of women with frankly invasive cancer and age-matched controls .In order to investigate the likely impact of changes in screening practice upon the incidence of invasive cervical cancer in the UK, we developed a mathematical model of cervical human papillomavirus (HPV) infection, cervical intraepithelial neoplasia (CIN) and invasive cervical cancer, and of screening in the UK population. The model was developed so that parameters such as the frequency of screening within various age groups and sensitivity of the screening test could be altered in a systematic way. We then evaluated the impact of the 2003 recommendations on cervical cancer incidence rates in the UK and also explored the impact of possible further changes in screening...

Long-term protective effect of high-risk human papillomavirus testing in population-based cervical screening

“…Cost-effectiveness studies and modelling studies show that cervical screening may become much more efficient in terms of decreasing numbers of false-negative and false-positive smears, if a test is used with a substantial higher sensitivity and long-term NPV than conventional cytology (Canfell et al, 2004). Negative test results in combined screening predicted that the future risk for lesions XCIN3 was very low.…”

Natural history and screening model for high‐risk human papillomavirus infection, neoplasia and cervical cancer in the Netherlands

“…[12][13][14][15][16] The presented model is largely similar in structure but differs from previous models in the description of regression of CIN lesions. Instead of confining to simultaneous hrHPV clearance and lesion regression, the model allows for a serial regression process where hrHPV clearance precedes lesion regression.…”

“…[12][13][14][15][16] Simulation enables us to combine the results of several studies, compare a large number of scenarios and provides an assessment of the costs and effectiveness in preventing cancer. A simulation model requires the specification of an underlying natural history model that describes health trajectories of women in an unscreened population.…”

Cost‐effectiveness of primary cytology and HPV DNA cervical screening

“…HPV-DNA testing before age 30 is not an FDA approved strategy and the benefits and costs of conventional cytology screening before age 30 are also unclear. 25,34,36,37 Globally, policies on when to start and stop screening, and screening intervals, vary considerably. 62,63 Implementation of screening policies based on evidence from cost-effectiveness studies remains not widely used, but the increasing quality and consistency of modeling studies is likely to eventually have impact on screening policies.…”

“…However, most modeling studies have consistently found similar reductions of the cumulative lifetime risk of invasive cervical cancer as a result of cytology and HPV DNA screening. 6,11,12,19,[23][24][25] State transition models are used in more than 85% of all costeffectiveness analyses and several cervical cancer state transition models have been reported previously. 26,27 The long-term effects and cost of cytology and HPV screening cannot be captured in clinical trials, where all studies have used surrogate endpoints, such as CIN grade 2 or 3 (CIN2-3).…”