Exclusive biannual mammography screening for women ages 50-69 years reduces the mortality from breast cancer among participants by 35%. Compared with 50% of clinically detected cancers, only 20% of carcinomas detected in screening have nodal metastases, and up to 55% of screening carcinomas are in the T1 stage of "minimal cancer." In many European countries (including Sweden, Norway, the Netherlands, and Great Britain), mammography screening programmes have been established for more than 10 years. In Germany, the aim is to establish, by 2008, a nationwide organised programme on the basis of the European Guidelines for Quality Assurance. This goal requires 80-100 mammography screening units. The first screening units went into use in 2005. Women between 50 and 69 years are invited to participate in 2-year intervals.