Up to 20 percent of invasive breast cancers are classified as triple negative, which refers to the fact that the cancer is estrogen receptor negative (ER-), progesterone receptor negative (ER-), and HER2 negative. In other words, triple negative breast cancers do not express receptors for estrogen or progesterone and do not overexpress HER2.
Triple negative breast cancer is also classified as basal or basal-like breast cancer by some researchers. Treatments that reduce the production of estrogen or block its effects in the body are not useful for this type of breast cancer.
Women with metabolic syndrome are more likely to have triple negative breast cancer upon diagnosis than women without it. A high cholesterol diet has been shown to induce angiogenesis and accelerate mammary tumor growth in a mouse model of triple negative breast cancer. On the other hand, use of lipophilic statins such as Zocor might reduce recurrence. The type 2 diabetes drug metformin has been shown to reduce the metastatic potential of triple negative breast cancer cells.
Systemic inflammation has been shown to increase the metastatic behavior of triple negative breast cancer cells.

Characteristics of women with triple negative breast cancer

Women diagnosed with triple negative breast cancer are more likely to be premenopausal than women with hormone receptor positive breast cancer. They are also more likely to be African American or Latina; among U.S. breast cancer patients, approximately 12% of non-Hispanic white, 20% of Latinas, and 28% of African Americans have triple negative breast cancer. One study found that 48% of BRCA1 mutation carriers had triple negative breast cancer compared to only 12% of noncarriers.

Some prescription drugs can increase ER-/PR-/HER2- risk

Use of selective serotonin reuptake inhibitors (SSRIs) such as Paxil and Prozac are suspected of increasing risk of (ER-/PR-) breast cancer in older women. Use of birth control pills has been found to be associated with risk of triple negative breast cancer in younger women.

Triple negative disease is often responsive to chemotherapy

Triple negative breast cancer is more often responsive to chemotherapy than hormone receptor positive breast cancer. On the other hand, long-term hormonal treatments (tamoxifen, aromatase inhibitors), which are used for ER+ subtypes, are not effective for triple negative breast cancer since estrogen is not the main driver of growth. Therefore, it is important for those with triple negative breast cancer to have surgery (and obtain clean surgical margins) and complete the chemotherapy that will in all likelihood be prescribed. The initial treatment period provides the best opportunity for a long or permanent remission. Please see our article on triple negative prognosis. Note that one 2015 study reported that stress hormones reduced the efficacy of Taxol in triple negative breast cancer cells.

Young TN patients should be considered for BRCA mutation testing

At least 10% of premenopausal triple negative breast cancer patients have BRCA1 mutations. Several researchers have suggested that all women under 50 with triple negative disease should be tested, even in the absence of a family history. However, most women without familial breast cancer would not qualify for testing under current guidelines.

Sources of information provided in this webpage

The information above, which is updated continually as new research becomes available, has been developed based solely on the results of academic studies. Clicking on any of the underlined terms will take you to its tag or webpage, which contain more extensive information.

Additional comments

There are specific foods that are associated with lower risk of this type of breast cancer and some that are associated with higher risk. Please see our article on what triple negative patients and survivors should eat.

Additional triple negative breast cancer articles

Below are links to other articles concerning triple negative breast cancer.