What is Breast Cancer?

A breast cancer is a malignant tumor that starts from cells of the breast. A malignant tumor is a group of cancer cells that may grow into (invade) surrounding tissues or spread (metastasize) to distant areas of the body. Breast cancer occurs mainly in women, but men can get it, too. Many people do not realize that men have breast tissue and that they can develop breast cancer.

What are the symptoms?

Initially, breast cancer may not cause any symptoms. A lump may be too small for you to feel or to cause any unusual changes you can notice on your own. Often, an abnormal area turns up on a screening mammogram (X-ray of the breast), which leads to further testing.

In some cases, however, the first sign of breast cancer is a new lump or mass in the breast that you or your doctor can feel. A lump that is painless, hard, and has uneven edges is more likely to be cancer. But sometimes cancers can be tender, soft, and rounded. So it's important to have anything unusual checked by your doctor.

According to the American Cancer Society, any of the following unusual changes in the breast can be a symptom of breast cancer:

• swelling of all or part of the breast

• skin irritation or dimpling

• breast pain

• nipple pain or the nipple turning inward

• redness, scaliness, or thickening of the nipple or breast skin

• a nipple discharge other than breast milk

• a lump in the underarm area

These changes also can be signs of less serious conditions that are not cancerous, such as an infection or a cyst. It’s important to get any breast changes checked out promptly by a doctor.