Design and analysis of cancer screening trials.

This article reviews approaches to the design and analysis of cancer screening trials. After summarizing some basic screening concepts and potential pitfalls, we introduce several possible screening trial designs with examples from the literature. We review in detail methods for analyzing screening trial data, including testing for a significant difference in disease-specific mortality between the control and intervention groups, estimating the mortality differential if one exists, and evaluating the programme lead time, the screen sensitivity and the role of stage shifting. We consider Overall mortality analyses, which are based on the experience of the trial population, and Limited mortality analyses, which are based on the experience of comparable groups of cases in the control and intervention groups. We discuss methods for selecting candidate comparable case groups and confirming that they are in fact comparable. We conclude by showing how the principles discussed have been used in the planning and design of a current screening trial for multiple cancers.