Preventing breast cancer: is it possible?

Breast cancer is a common cause of suffering and death in Australia. Improvements in detection and therapy will make only small inroads into mortality, and will not reduce suffering. Reducing the incidence of breast cancer by preventive measures is a logical step, and this paper reviews how it might be achieved. Reducing the population's exposure to known risk factors for breast cancer is logical; however, the potential for improvement is limited. Reduction in age at first pregnancy is impractical and measures such as weight reduction and reducing consumption of fat and alcohol are likely to be only partially successful. Increasing activity in youth is a concept that requires further investigation, but is a possible area of promise. Exogenous hormone use probably contributes little to the incidence of breast cancer, but prescribing patterns for post-menopausal oestrogens are changing and require monitoring. The use of hormone manipulation to prevent breast cancer has considerable potential benefit. Two approaches have been proposed. The first involves reversible suppression of ovarian function by luteinizing hormone-releasing hormone (LHRH) agonists after child-bearing has finished, combined with low-dose conjugated equine oestrogen to compensate for oestrogen loss. The other involves the use of the anti-oestrogen, tamoxifen. Both measures have the potential to halve breast cancer incidence. There is some evidence that non-hormonal chemoprevention is possible, but clinical trial data are lacking.