BASAL-LIKE BREAST CANCER
The gene expression profile for basal-like breast cancer (BLBC) frequently classifies breast cancer type Triple Negative Breast Cancer (TNBC) as virtually the same.
Triple Negative Cancer has similar characteristics to BLBC insofar as they both have three negative expressions of,
1. Estrogen (ER) Receptor
2. Progesterone (PR) Receptor
3. Human Epidermal Growth Factor Receptor 2 (HER-2)
The defining characteristics of the BLBC gene expression is the extra unique basal cluster of mutated gene – BLBC changes in the proteins that TNBC usually do not have.
I suppose, while TNBC is solely defined by what it is not, BLBC can mildly say it has a bit more of this a little less of that?
Also, there are BLBCs that are not TNBCs in a small fraction of cases called non-basal-like breast cancers (NBL)
Nor is the distinction between BLBC and TNBC merely academic. TNBC tumors that express basal markers have caused damage associated with worse survival than TNBC tumors that do not have basal-like markers.
OF ALL THE GENE SUBTYPES
1. Basal-like breast cancer (BLBC) remains the greatest challenge because it’s the most aggressive with the poorest outcomes.
2. Unlike ER-positive luminal tumors and HER-2 positive tumors, the basal-like subtype lacks expression of the molecular targets (receptors) that respond to highly effective targeted therapies such as
a) Tamoxifen & aromatase inhibitors (Estrogen related) &
b) Trastuzumab (HER2 amplification) medications.
3. Indeed, identification of the relevant targets in BLBC remains a heavy challenge.
4. Fortunately, BLBC and TNBC respond to chemotherapy.
For example, significant variation exists in the genetic/molecular features of TNBC.
IN 2016, FURTHER CLASSIFICATIONS WERE PROPOSED REFINING TNBC INTO SUBTYPES.
Apart from the apparent diversity of TNBC in women of African ancestry, we do not know enough to say much more than the following,
The mutated BRCA gene seems to be heavily associated with women of African ancestry.
Eighty per cent of women who carry the mutation in BRCA1 and develop breast cancer have basal-like cancer.
However, most basal-like breast cancers are not in women with BRCA 1.
On this basis, basal-like breast cancer appears to have more than one origin, or at least, it is not solely due to inheritance.