Screening for Breast Cancer: An Overview

Abstract

There has been a remarkable improvement in the examination methods of the breast, especially of mammography during the seventies and eighties. Mammography alone has convincingly demonstrated its ability to lower the diagnostic threshold substantially (i.e., to detect large numbers of very small cancers). When using mammography as a screening method, one can hope to prevent many breast cancers from developing into incurable stages. However, there are various, well-known biases associated with screening (lead-time bias, length bias sampling, detection bias, etc.). Before one draws conclusions regarding the benefit from the diagnostic improvements, it is vital to perform population-based, randomized, controlled trials in order to avoid decisionmaking on the basis of assumed benefits. This is the best way to determine whether a significant number of advanced carcinomas can be eliminated as an effect of screening and whether significant reduction in mortality from breast cancer can be achieved.