Triple negative breast cancer (TNBC) gets its name from the fact that the cancer cells test negative for 3 different things:
Because these tumours are negative for these things, standard treatments for breast cancer, such as hormonal therapy or trastuzumab (Herceptin) cannot be used with this type of breast cancer.
Basal-like (or basal type) breast cancer has a certain genetic pattern. These cancer cells make abnormally large amounts of the protein cytokeratin5/6 and have too many epidermal growth factor receptors (EGFRs), which signal cell growth and division. In addition to this genetic pattern, basal-like breast cancers are often triple negative. To date, however, there is no internationally accepted definition for basal-like cancers, and there is no genetic test available in clinical practice to identify these tumours.
It is important to remember that triple negative breast cancer and basal-like breast cancer are not the same.
- Some triple negative breast cancers have basal-like genetic patterns, but not all do.
- While most basal-like breast cancers are triple negative, a small but significant number may be hormone receptor or HER2 positive.
Triple negative tumours are most often invasive ductal cancers, but ductal carcinoma in situ may also be triple negative.
Women under the age of 40 and women of African or Asian ancestry are at higher risk for developing triple negative or basal-like breast cancers. Women with BRCA1 gene mutations are at higher risk of developing basal-like breast tumours that are also triple negative.
Triple negative and basal-like breast cancers also differ from other types of breast cancer:
- Many are interval cancers that develop between regularly scheduled screening mammography.
- Most are high-grade, aggressive tumours.
- Many are diagnosed at a later stage (the cancer has already spread to the lymph nodes or other organs).
- These tumours spread (metastasize) or recur in the brain or lung more frequently than other types of breast cancer, which commonly metastasize to the bones or the liver.
- Triple negative and basal-like tumours respond well to chemotherapy at first, but they tend to recur quickly after treatment.
- These cancers usually recur within the first 5 years after treatment.
- The prognosis for triple negative and basal-like breast tumours is less favourable than other types of breast cancer.
Treatment options for triple negative and basal-like breast cancer are similar to other types of breast cancer, and may include:
- breast-conserving surgery
- axillary lymph node dissection
- external beam radiation therapy
- combinations containing anthracycline drugs
- doxorubicin (Adriamycin)
- epirubicin (Pharmorubicin)
- combinations containing taxane drugs
- paclitaxel (Taxol)
- docetaxel (Taxotere)
- platinum-based drugs may work better against triple negative and basal-like tumours
- cisplatin (Platinol AQ)
- carboplatin (Paraplatin, Paraplatin AQ)
- For more detailed information on specific drugs, go to sources of drug information.
Research is underway to find out:
- which chemotherapy drugs work best for triple negative tumours or basal-like tumours
- whether there are different treatments needed for triple negative tumours and basal-like tumours
- whether chemotherapy given with less time between treatments (dose dense) is more effective