Triple-negative breast cancer (TNBC) describes cancers that lack any or much of the three most common types of receptors known to fuel the growth of breast cancer: estrogen receptor, the progesterone receptor, and the human epidermal growth factor receptor 2 (HER2). Clinically, triple-negative breast cancers are more aggressive than are other types of breast cancer. They are treated by chemotherapy.
TNBC makes up about 15-20% of all breast cancers diagnosed worldwide. It is more commonly diagnosed in women younger than 40 and in African American women.
Clinical studies have shown that other types of breast cancer generally have more favorable outcomes than TNBC. One study of more than 1,500 Canadian women treated for breast cancer showed that the likelihood of distant recurrence and death within five years was significantly higher in women with TNBC than in those with other types of the disease. A study from the California Cancer Registry of more than 6,000 women with TNBC showed that women with this form of the disease were more likely to be diagnosed at a later stage than were women with other types of breast cancer and had shorter survival periods, regardless of the stage at which they were diagnosed. African American women had the lowest overall survival of any groups in this study. Other research in a series of 190 women with breast cancer in Georgia showed similar findings, with women with TNBC more likely to experience recurrences and fatal events than did those with other types of breast cancer.
As noted above, chemotherapy remains the only treatment option for these tumors; other therapies appear to be ineffective. Neoadjuvant chemotherapy (NACT), chemotherapy administered prior to surgery, is the standard of care for women with locally advanced breast cancer (at least Stage 3) or inflammatory breast cancer. For stage 2 TNBC, neoadjuvant chemotherapy is increasingly being used to improve surgical outcomes and to help the clinician ascertain how sensitive a given tumor is to the treatment. An absence of tumor in the final surgical specimen after NACT can help the surgeon determine the treatment’s success; such patients have been shown to have improved disease-free and overall survival.
Because TNBC is one of the most aggressive types of breast cancer with the fewest treatment options, active research in this area is critical . PARP inhibitors, substances that affect an enzyme that promotes cancer’s growth, have shown promise in both animal models and clinical trials as an effective treatment for certain cancers; TNBC may be one of these, although questions remain about which chemotherapies to use with the PARP inhibitor in these cancers.
A number of clinical studies are now ongoing (recruiting) in an effort to improve the treatment of triple-negative breast cancer.
For more information about clinical trials, please visit the website: Pbcc.me/TNBC