Our latest article from the Current Concepts review series, “Triple-Negative Breast Cancer,” comes from Drs. William D. Foulkes, Ian E. Smith, M.D., and Jorge S. Reis-Filho, and focuses on its origin, molecular and clinical characteristics, and treatment.
Triple-negative breast cancers are defined as tumors that lack expression of ER, progesterone receptor (PR), and HER2. Their rapid growth and frequent occurrence in young women can make mammographic detection difficult.
• What is the epidemiology of triple-negative breast cancer?
Triple-negative and basal-like tumors account for about 15% of all invasive breast cancers, and they usually have a high histologic grade. Both triple-negative and basal-like breast cancer occur more frequently in young black and Hispanic women than in women of other racial or ethnic groups. As compared with women without cancer, women in whom basal-like breast cancer develops reach menarche at an earlier age than do women without cancer and have a higher body-mass index during their premenopausal years, higher parity, and a lower lifetime duration of breast-feeding.
• What are the clinical features of triple-negative breast cancer?
Triple-negative and basal-like breast cancers tend to be larger than other subtypes of breast cancer and are usually high-grade, invasive ductal carcinomas of no special type. Differences in nodal status are less clear-cut, but a large study has shown that basal-like breast cancers are more likely than other types of breast cancer to be node-negative. Both triple-negative and basal-like breast cancers are characterized by an unusually attenuated relationship between the size of the primary tumor and the probability of survival.
Morning Report Questions
Q: What is the mainstay of medical treatment for patients with triple-negative breast cancer?
A: Women with triple-negative breast cancer do not benefit from endocrine therapy or trastuzumab. Chemotherapy is currently the mainstay of medical treatment, although patients with triple-negative disease, when considered as a group, have a worse outcome after chemotherapy than patients with breast cancers of other subtypes.
Q: What is the prognosis for patients with triple-negative breast cancer?
A: Multiple studies have indicated that triple-negative and basal-like breast cancers, as a group, are associated with a poor prognosis. The shape of the survival curve for patients with triple-negative or basal-like breast cancer differs from that for patients with other types of breast cancer: there is a sharp decrease in survival during the first 3 to 5 years after diagnosis, but distant relapse after this time is much less common. Both triple-negative and basal-like breast cancers are more likely than other types of breast cancer to metastasize to viscera, particularly to the lungs and brain, and are less likely to metastasize to bone.