Studies of apoptosis in breast cancer

Breast cancer is the commonest malignancy in women and comprises 18% of all cancers in women. The United Kingdom has the highest age standardised incidence and mortality from breast cancer in the world.1 Since 1990, death rates from breast cancer have decreased by over 25%, and this is at least in part due to the improved use of adjuvant tamoxifen and chemotherapy. Current research is focused on a greater understanding of the response and resistance to treatment, including the role of apoptosis. Accessibility of the primary tumour makes breast cancer uniquely suitable for such studies. Here we summarise and integrate the data on apoptosis and its role in the development, prognosis, and treatment of breast cancer.

Normal breast development is controlled by a balance between cell proliferation and apoptosis, and there is strong evidence that tumour growth is not just a result of uncontrolled proliferation but also of reduced apoptosis. The balance between proliferation and apoptosis is crucial in determining the overall growth or regression of the tumour 2 3 in response to chemotherapy, radiotherapy and, more recently, hormonal treatments. All of these act in part by inducing apoptosis.4^–6 Thus it is possible to delineate the biology of individual tumours at the molecular and biochemical level by examining apoptosis and its control and regulation and to exploit these to clinical advantage. Much of this work is still the subject of research. Understanding these relations could allow individually tailored treatments to maximise tumour regression and the efficacy of treatment. It could also help to answer why some tumours fail to respond and thereby indicate new routes of drug development.