, reflecting different rates of tobacco exposure. In contrast, female breast cancer is the most frequently diagnosed cancer in most countries, reflecting less modifiable internal hormonal influences. 5-10% of these cases arise from heritable causes such as susceptibility to breast cancer and ovarian cancer conferred by cancer susceptibility genes such as BRCA1 and BRCA2 . A typical woman’s lifetime risk of breast cancer is about 12%, rising to 70% for a woman carrying one of these mutations.