Breast cancer has a wide variety of subtypes. The prognosis and treatment options depend on the characteristics of the particular cancer cells. Dr. Rafael Santana-Davila and Dr. Edith A Perez of the Mayo Clinic in Jacksonville, Florida provided a review of triple negative breast cancer, one of the most difficult to treat.
Some breast cancers have receptors for at least one of the following: estrogen, progesterone, or human epidermal growth factor. The presence of one or more of these receptors provides options for targeted therapies that attack the cancer cells with minimal damage to healthy cells. Triple negative breast cancer (TNBC) has none of these three receptors. Thus, chemotherapy options have to be less specific and more cytotoxic.
TNBC is related to basal-like breast cancer and BRCA deficient cancers. The term basal-like comes from the structure of the milk ducts, which have two layers: an inner luminal cell layer, and an outer basal cell layer. Basal-like cancers have characteristics of the basal cells, although they do not always start in this layer.
BRCA refers to two genes, BRCA1 and BRCA2, which are involved in repairing DNA double-strand breaks. Women with BRCA mutations are at increased risk of breast, ovarian, and pancreatic cancers. Men with the same genetic mutation are at risk for prostate cancer.
Santana-Davila and Perez illustrated the relationship of TNBC, basal-like breast cancer, and BRCA deficient cancer as three circles that partially overlap. An individual patient can have breast cancer with any one, two, or three of these classification features.
Chemotherapy treatment options for triple negative breast cancer include:
1. Platinum agents,
2. Anti-tubulin agents,
3. Anti-angiogenic agents, which block the formation of new blood vessels and limit tumor size,
4. Targeted therapies based on other cancer cell characteristics.
Dr. Reinaldo D. Chacon and Maria V. Costanzo of the Alexander Fleming Institute in Argentina reported, triple negative breast cancer tumors account for approximately 15 percent of all breast cancers. General characteristics of the triple negative type include: