Each breast contains 15 to 20 lobes of glandular tissue, arranged like the petals of a daisy. The lobes are further divided into smaller lobules that produce milk for breast-feeding. Small tubes ducts conduct the milk to a reservoir that lies just beneath your nipple. After skin cancer, breast cancer is the most common cancer diagnosed in women in the United States. Breast cancer can occur in both men and women, but it's far more common in women.
Each year, more than , American women and men are diagnosed with breast cancer. No one knows if or when breast cancer will develop, but understanding the risk factors for breast cancer may help you take preventive measures to reduce the likelihood of developing the disease. Breast cancer is caused when the DNA in breast cells mutate or change, disabling specific functions that control cell growth and division. In many cases, these mutated cells die or are attacked by the immune system. But some cells escape the immune system and grow unchecked, forming a tumor in the breast. Aging: On average, women over 60 are more likely to be diagnosed with breast cancer.
Skip to Content. Have questions about breast cancer? Ask here. Use the menu to see other pages. Although risk factors often influence the development of cancer, most do not directly cause cancer.
Not all women have the same risk for developing breast cancer over a lifetime. Certain factors increase a woman's risk, and some have a bigger impact on risk than others. However, having several risk factors doesn't mean you'll inevitably develop breast cancer. Likewise, having few risk factors doesn't mean that you'll never develop it.