Despite efforts in recent years to reduce the number of deaths caused by breast cancer it is still the most common cancer occurring in women. Approx. 47,500 new cases of the disease appear in Germany per year, a situation comparable with other European countries and with the USA. In 2004 alone, 17,592 women died from the sequela of a breast carcinoma (Federal Statistics Office statistics on causes of death), the inference being that about 10% of women can expect to suffer from breast cancer in the course of their lives. The likelihood of suffering from breast cancer increases as a function of age (Table 1), so that a 50-year old woman has a roughly 4.3% risk of developing the disease in the next 20 years of her life.