Clinical: Breast cancer screening.(Disease/Disorder overview)

Contributed by Dr Imogen Locke, clinical research fellow in cancer genetics and Dr Rosalind Eeles, consultant and reader in clinical cancer genetics, Royal Marsden NHS Foundation Trust.

1. AETIOLOGY AND EPIDEMIOLOGY

Breast cancer is the commonest cancer in women in the UK. It is estimated that one in nine women in the general population will develop breast cancer during their lifetime. Breast cancer is a multifactorial disease linked to lifestyle and environmental factors, reproductive history and inherited susceptibility.

Family history

Family history is an important risk factor for both breast and ovarian cancer. The breast cancer risk of women with a single affected first degree relative is approximately twice that of the general population. Clustering of breast cancer cases in a family may occur simply by chance because breast cancer is a common disease, be due to shared lifestyle and/or environmental factors or due to a genetic susceptibility.

Twin studies predict that up to 27 per cent of breast cancer may be due to an inherited susceptibility. Only about 5 per cent of all breast cancer is thought to be due to the inheritance of highly penetrant breast …