What Causes Triple Negative Breast Cancer?

Many patients wonder what causes triple negative breast cancer. The breast cancer experts at Moffitt Cancer Center are often asked this question, but as of yet, there are no clear answers. As research continues, more is being learned about the causes of breast cancer in general, and triple negative breast cancer specifically.

Triple negative breast cancer differs from other types of breast cancer in that the cancer cells do not have receptors for estrogen, progesterone or HER-2/neu hormones. When these receptors are present and exposed to the corresponding hormones, they can stimulate the cancer to grow. But, this also means that triple negative breast cancer patients do not benefit from hormone-based treatments, such as tamoxifen and Herceptin, which are sometimes effective for treating hormone-receptor-positive cancers.

The current theories on what causes triple negative breast cancer and hormone-receptor-positive cancers also differ. For instance, some breast cancers that grow in response to hormone exposure have been linked to a woman’s childbearing characteristics, such as the age at which she gave birth for the first time. Triple negative breast cancer does not seem to share this link.
Some researchers believe that one possible cause of triple negative breast cancer is a faulty BRCA1 gene. Here are some of the factors that support this theory:

• Everyone inherits one set of BRCA1 genes from each of their parents.
• When these genes function properly, they help prevent the development of cancer.
• A BRCA1 gene mutation is believed to make the body’s cells susceptible to further genetic alterations that can lead to certain types of cancer, including various forms of breast and ovarian cancer.
• Most breast cancers that are caused by a damaged BRCA1 gene are triple negative.

As a National Cancer Institute-designated Comprehensive Cancer Center, Moffitt continues to lead the way in breast cancer research. Through robust clinical trials and extensive studies, we are making significant strides in understanding breast cancer and developing more effective approaches to risk assessment, prevention, detection and treatment.