The aim of the BreastScreen Australia Program is to detect invasive breast cancers in women early while they are small and before they have spread beyond the breast; this gives the best chance of effective treatment.This report presents information on breast cancer size and nodal status supplied by BreastScreen Australia and State and Territory cancer registries. It is based on all invasive breast cancers diagnosed in Australia in 1997, and includes tumours diagnosed in women known to have had breast cancer previously.