Triple negative breast cancer is a type of basal cell cancer where the cancer cells do not display any estrogen receptors (ERs), progesterone receptors (PRs) or HER2 receptors.

Breast cancers are often described according to the presence or absence of these proteins and while women with cancer cells displaying the estrogen receptor are said to have an ER- positive cancer, those with none of these receptors are classed as having a triple negative cancer.
 

These proteins present on the surface of cancer cells pick up messages which promote the cells' growth. The main importance of knowing if a cancer of the breast is triple negative is to determine the possible outcome of the cancer and its treatment options.

If a woman has an ER-positive cancer, for example, the cancer cells may receive signals from estrogen that promote their growth. This is also referred to as an estrogen dependent cancer. A hormonal therapy that can decrease the amount of estrogen present in the body can therefore limit the growth of an ER-positive cancer.

Women who have a triple negative cancer do not respond to hormonal therapy and are instead advised to undergo chemotherapy. Surgery is performed to remove the cancer after chemotherapy. Radiation therapy may also be beneficial in some cases.

In the United States, around 15 to 20 percent of all breast cancers are triple negative. Triple negative cancer is more common in women with certain characteristics. Some factors associated with this type of cancer include:

• Young age - Triple negative cancers are more common among younger women aged under 40 years.
• African American women and women of Hispanic/Latina ethnicity are more likely to suffer from this cancer.
• Women with BRCA1 mutations are more likely to get triple negative cancer.

Triple negative breast cancers are often very aggressive and tend to grow and spread quickly. They are also less likely to be detected on an annual mammogram and to spread to other parts of the body such as the brain, liver and bones. These cancers also tend to recur after treatment and remission meaning that overall, the prognosis for triple negative breast cancer is often poorer than with hormone positive cancers.