Prognostic and predictive factors in breast cancer

Around 570 000 women develop breast cancer worldwide. In the U.K. it affects 33 000 women and causes 16 000 deaths each year. Treatment of early breast cancer is surgical, comprising breast conserving surgery (followed by radiotherapy) for small unifocal tumours, or mastectomy for larger or multifocal tumours. Survival of patients with breast cancer depends on two different types of prognostic factors: tumour size reflecting how long the tumour has been present, and biological factors (i.e. grade) which represent tumour aggressiveness. In women with a tumour that has adverse features predicting early recurrence (i.e. lymph node positivity, large size, high grade) adjuvant systemic chemo- or hormonal therapy is given to reduce the risk of relapse. Chemotherapy is given to pre-menopausal women for oestrogen receptor negative post-menopausal breast cancer, whereas hormone therapy is reserved for oestrogen receptor positive cancer. Since 50% of patients will never relapse, identification of which women are at high risk of recurrence is necessary so as to offer treatment with adjuvant therapy. The use of hormone therapy and chemotherapy has been aided by factors predicting the likelihood of response, e.g. oestrogen receptor status. The value of newer prognostic and predictive markers is addressed.