Cause

The exact cause of breast cancer is not known. A woman's age and health history play a part. The chances that you will get breast cancer increase as you age. In the United States, 1 woman out of 8 will be diagnosed with breast cancer at some point in her life.²

To learn more, see What Increases Your Risk.

Symptoms

The first sign of breast cancer is often a painless lump. But early breast cancer is often found on a mammogram before a lump can be felt.

Other symptoms of breast cancer may not appear until the cancer is more advanced. These include:

• A thickening in the breast or armpit.
• A change in the size or shape of the breast.
• Changes in the skin of the breast, such as a dimple or skin that looks like an orange peel.
• A change in the nipple, such as scaling of the skin or a nipple that turns in.
• A green or bloody fluid that comes from the nipple.
• A change in the color or feel of the skin around the nipple (areola).

Symptoms such as changes in the skin of the breast or the nipple may be a sign of inflammatory breast cancer. For more information, see the topic Inflammatory Breast Cancer.