Breast Cancer

What is breast cancer?

Breast cancer is the most common type of cancer among women in the United States. Any type of tumor that forms in the breast is considered breast cancer. Although tumors may begin to form in the breast, they also have the potential to grow into surrounding tissue or metastasize to other areas of the body.

What are the different types of breast cancer?

Breast cancer is classified by the stage, or progression, that it's in when discovered. The stages range from stage 0, meaning the cancer is non-invasive, to stage IV, which means the cancer has metastasized, or moved to different parts of the body.

The most common types of breast cancer are:

Ductal carcinoma in situ (DCIS)

Approximately 20 percent of cases of breast cancer are ductal carcinoma in situ (DCIS). DCIS is considered non-invasive. It occurs when cancer cells are only found in the lining of the milk ducts. This means that the cancer has not spread to other areas of the breast.

Invasive ductal carcinoma

Invasive ductal carcinoma is the most common type of breast cancer. In invasive ductal carcinoma, the cancer cells that started to grow in the lining of the milk ducts have spread to other areas of the breast. Invasive ductal carcinoma may metastasize to other parts of the body.

Invasive lobular carcinoma

Lobular breast cancer forms in the lobes, the glands that make milk, of the breast. In invasive lobular carcinoma, cancer cells have spread from the lobes into other breast tissue. Approximately 10 percent of breast cancer cases are invasive lobular carcinoma.

Inflammatory breast cancer

Inflammatory breast cancer is a rare type of breast cancer that has spread to the skin of the breast. In inflammatory breast cancer, the skin will appear red, swollen or dimpled, and may feel warm to touch.

Other types of breast cancer

Other subtypes of carcinoma can include tubular, mucinous and medullary. Male breast cancer is also rare.

What are the symptoms of breast cancer?

Symptoms of breast cancer can vary depending on the type of breast cancer and the patient. Some cases of breast cancer show no signs or symptoms. Common symptoms of breast cancer include:

  • A lump in the breast or armpit
  • Pain or tenderness of the breast
  • Swelling or thickening of the breast
  • Change in shape or size of the breast
  • Skin irritation on the breast
  • Nipple discharge (other than breast milk)

If symptoms indicate breast cancer as a possible diagnosis, a doctor will perform a series of diagnostic tests, which may include a physical exam, imaging tests and/or biopsies.

What are the causes and risk factors of breast cancer?

Breast cancer is caused by a gene mutation which may be inherited or acquired, although the cause of the mutation is unknown. The risk of developing breast cancer may be affected by some genetic and environmental factors, including:

  • Age
  • Age at start or menstruation
  • Age at start of menopause
  • Age at birth of first child
  • Not giving birth or breastfeeding
  • Family history
  • BRCA1 or BRCA2 gene changes
  • Use of hormone-replacement therapy
  • Radiation exposure
  • Density of breast tissue
  • Being overweight
  • Lack of exercise
  • Alcohol consumption

How is breast cancer treated?

Breast cancer treatment varies depending on the type and stage of the cancer, as well as the patient's medical history and overall health.

Common breast cancer treatments include surgery, chemotherapy and/or radiation therapy.

Following breast cancer treatment, women commonly undergo reconstructive surgery.