ABSTRACT
Breast cancer is the most common cancer affecting women. A woman in the developed world has a lifetime risk of developing breast cancer of as much as 12%. The clustering of breast cancer in families is almost entirely due to genetic variation rather than shared lifestyle or environment. The risk of developing breast cancer is twice as high in women who have an affected first-degree relative compared to women in the general population. Once the family history has been collected, the reported diagnoses should be confirmed by reviewing medical records, pathology reports and cancer registry records. Chemoprevention may reduce a woman's risk of developing breast cancer by up to 40%, although the reduction appears to be confined to oestrogen receptor (ER) positive cancers, and since BRCA1 gene carriers have a propensity to develop ER negative cancers, the benefits in this group are less clear.
