Evaluating cervical cancer screening programmes for developing countries.

This study evaluates cervical screening programmes for regions of the world where resources are scarce and little screening currently takes place. It investigates infrequent screening and programmes in which as many women as possible are screened just once in their lifetime. It also compares the effectiveness of cytology and human papillomavirus (HPV) testing for primary screening. Different programmes are evaluated by a stochastic model of the progression of pre-cancer, its relationship to papillomavirus infection and the diagnostic accuracy of alternative screening methods. These are compared in terms of the impact on the incidence of invasive cancer and resource use. Important factors that determine the suitability of different screening programmes are the available resources and the expected population coverage. Blanket screening for women aged 30-59 years, with the aim of covering all just once in their lifetime, could reduce the incidence of invasive cancer by up to 30%. A 10-year programme would require about 50% more routine screening tests to bring about the same reduction in incidence and a 5-year programme about 2.5-3 times as many. With either approach it would be more effective for resource use to concentrate on screening women aged 30-59 than a wider age group. Whether HPV testing would be more effective as a primary screening method than cytology depends on the underlying prevalence of HPV infection, the accuracy of cytology, the cost and the suitability of the testing procedure under field conditions.