Genetic determinants of breast cancer

Breast cancer is the most common malignancy in women in the Western world and it is estimated that women who survive to the age of 85 years will have a 1 in 9 lifetime probability of developing this type of neoplasia (1, 2). The degree of risk is not spread homogeneously across the general population (2). The vast majority of risk factors associated to breast cancer susceptibility are related to hormonal exposure, either from endogenous sources such as early age at menarche, late age at menopause, late pregnancy or nullliparity, overweight and obesity, or exogenous sources such as the use of hormone replacement therapy (HRT) (3). Other risk factors include alcohol intake, radiation exposure, current age, past history of breast cancer and the history of a breast biopsy (2). Additionally, a recent study has shown that the risk of breast cancer is increased by 3% per pack/year of cigarette smoking when it is done between menarche and first childbirth (4).