A diagnosis of triple negative breast cancer means that the three most common types of receptors, known to fuel most breast cancer growth, estrogen, progesterone and the HER-2 (hormone epidermal growth factor–receptor 2) gene, are not present in the cancer tumor. Receptors are proteins found inside and on the surface of cells. Some patients lack these receptors; when this occurs, the breast cancer is called triple negative. Triple negative breast cancer means the tumor is estrogen-receptor negative, progesterone-receptor negative and HER-2 negative. Testing negative for all three means the cancer is triple negative.

Triple negative breast cancer is more likely to affect women:

• Before age 40 or 50,
• African-American and Hispanic women, and
• People with BRCA1 mutation.

Triple negative breast cancer does not respond to hormonal therapy, such as Tamoxifen, or therapies that target HER-2 receptors. Like other forms of breast cancer, triple negative breast cancer is treated with surgery, radiation therapy and chemotherapy. Five-year survival rates tend to be lower for triple negative breast cancer.

Triple negative breast cancer tends to be higher grade than other types of breast cancer and is more likely to spread and recur. The higher the grade, the less the cancer cells resemble normal, healthy breast cells in their appearance and growth rate. On a scale of 1 to 3, triple negative breast cancer often is grade 3.