Although much has been written about overdiagnosis in mammographical screening, analytical estimates of the extent of overdiagnosis are rare in the literature. Estimates specific to ductal carcinoma in situ (DCIS) and the implications for future invasive disease are even more difficult to find. In this paper, we review studies of incidence of DCIS within breast screening programmes and its association with subsequent incidence of invasive breast cancer. Although sparse, published results suggest that the majority of DCIS cases have the propensity to progress to invasive disease.
