Breast cancer remains a major public health problem. Increase in numbers of women with major breast cancer risk factors, including a lower age of menarche, late age of first pregnancy, fewer pregnancies, shorter or no periods of breastfeeding, and a later menopause. Other risk factors which add to the burden of breast cancer are the increase in obesity, alcohol consumption, inactivity, and hormone replacement therapy (HRT). The goal of primary breast cancer prevention is to protect women from developing breast cancer. The goal of secondary breast cancer prevention is to prevent recurrence of breast cancer. Prophylactic pharmacologic therapy should be considered for inclusion in breast cancer prevention programs for select at-risk women. Breastfeeding appears to reduce the risk of breast cancer. The ovaries are the body’s main sources of estrogen, a hormone that can help some breast cancers grow.