Cancers induced and cancers detected in a mammography screening programme.

The numbers of cancers which might be induced in a breast screening programme are compared with the numbers detected. The induction rate is estimated from reports of breast cancer in various groups exposed to high radiation doses, and also from International Commission on Radiological Protection risk estimates. An apparent discrepancy between these two approaches is discussed and removed. Detection rates are based on preliminary results in Edinburgh, and greatly exceed the induction rate. Whether such an excess is maintained if an X-ray grid requiring a higher dose is used on younger age groups is discussed.