Key questions involved in the treatment of disseminated breast cancer are discussed in this well-presented overview. It is the result of an initiative taken by the Swiss Group for Clinical Cancer Research to reveal the most recent developments in experimental and clinical research. The topics discussed include: the comparison of in vitro cultures of epithelial cells with breast cancer cells, the effect of steroids and their antagonists, the involvement of suppressor genes in tumour progression, the modulation of transforming growth factors by estrogen, and prognostic factors such as cERB-2 and EGF-R in breast cancer.