Screening strategies for cervical cancer and cervical intraepithelial neoplasia.

Exfoliative cytology is a highly sensitive and inexpensive screening technique for cervical cancer and its precursors. The detection and eradication of the precursors have led to a significant fall in cervical cancer incidence rates and death rates in those areas in which there has been widespread and prolonged use. Recently, however, the utility and cost-effectiveness of cytology has been questioned, and it has been suggested that screening strategies be altered. A consideration of the effect of the transit times of cervical intraepithelial neoplasia on screening intervals and the impact of the changing patterns of cervix cancer epidemiology on screening strategy suggests that a significant change in screening intervals may be counterproductive.