Screening mammography - early detection or over-diagnosis? Contribution from Australian data

Objective The aim of this review was to examine the benefits and harms of organized screening mammography, with particular reference to data from Australia. Methods Published literature was examined relating to the impact of screening mammography on breast cancer-specific mortality, the trends in use of adjuvant treatments for breast cancer, the effectiveness of adjuvant treatment in terms of breast cancer-specific mortality, the impact of breast cancer treatment on non-breast cancer mortality and the magnitude of the issue of over-diagnosis. Results Most of the recent reduction in breast cancer-specific mortality is explained by use of adjuvant therapy rather than screening mammography. The impact of screening mammography in countries where women present with early disease and have access to adjuvant treatment is modest. There is a wide range of estimates for the magnitude of over-diagnosis. All-cause mortality (rather than breast cancer-specific mortality) should be used when assessing the impact of mammographic screening as otherwise the harm of breast cancer treatment in women who are over-diagnosed will be missed. Conclusions The benefits and harms of screening mammography are finely balanced. The impact of screening mammography is at best neutral but may result in overall harm. Women should be informed of the issue of over-diagnosis. It is time to review whether organized mammographic screening programs should continue.