Breast Cancer: Causes

What causes breast cancer?

The underlying cause of breast cancer is currently not known. However, it is believed that some cases of breast cancer are genetic and may be linked to certain defects of genes called BRCA1 and BRCA2.

Normally, cells in the breast that are old or damaged will stop reproducing and die. These cells are replaced by healthy young cells. Breast cancer occurs when old or damaged cells divide and multiply uncontrollably. This results in the development of a malignant mass of tissue (tumor) in the breast.

If left untreated, breast cancer cells can continue to multiply, spread to other parts of the body, and interfere with more of the body’s vital processes.

What are the risk factors for breast cancer?

A number of factors are thought to increase your chances of developing breast cancer. Not all people with risk factors will develop breast cancer.

Risk factors for breast cancer include:

• Beginning menstruation before age 12

• Being older than 50 years of age

• Exposure to high doses of radiation, such as from radiation therapy in the chest area

• Going through menopause after age 55

• Having certain defects of BRCA1 and BRCA2 genes

• Never having children or having a first child after age 30

• Obesity

• Personal or family history of breast cancer

• Taking drugs that contain the hormone estrogen

• Having taken diethylstilbestrol (DES), a drug prescribed in the 1940s–1960s to prevent miscarriage

Reducing your risk of breast cancer

You may be able to lower your risk of breast cancer by:

• Eating a diet that is low in fat and salty and smoked foods, and high in fiber and fruits and vegetables

• Maintaining a healthy weight

• Not drinking alcohol or limiting alcohol intake to one drink per day for women and two drinks per day for men