Molecular subtypes of breast cancer
There are many different types of breast cancer. Some are slow
growing and "well behaved" while others are much more aggressive.
Traditional pathology reporting describes the cancer by the
appearance of the cells under the microscope as ductal / lobular or
special type. This appearance does not however reliably predict the
behaviour of the tumour. Recent advances in pathology have
allowed a much more detailed analysis of the structure of the
cancer cells at a molecular level.
Using these methods researchers have identified four main groups
of breast cancer.
Subtype
|
Molecular features
|
Prevelance
|
Luminal A
|
ER+, +/-PR+,HER2 - , lowK67
|
40%
|
Luminal B
|
ER+, +/-PR+, HER2+(or HER2- with high Ki67)
|
20%
|
Basal
|
ER-, PR-, HER2-,cytokeratin5/6+
|
15%
|
HER 2 type
|
ER-,PR-, HER2+
|
15%
|
Normal breast like
|
Cancers that cannot be satisfactorily classified in 4 groups
above
|
10%
|
Luminal A
The cancer cells look similar to the ductal cells on the inside
lining of the breast ducts. (the lumen of the duct is the space
inside and the luminal cells are the layer of cells closest to this
surface)These tumours appear to have the best prognosis. Treatment
can include hormonal manipulation as they are receptor
positive.
Luminal B
These tumours have a poorer prognosis and tend to occur in
younger women.
Basal like tumours
These tumours have cells that look more like the cells on the
outer layer of the duct lining. Most contain p53 mutations. Most
basal tumours are triple negative which means that the cells do not
express the oestrogen, progesterone or HER2 receptors. Treatment
options are limited as we cannot use anti-oestrogen drugs like
Tamoxifen or the Aromatase Inhibitors. Herceptin is also of no use
in this situation. The medical oncologists will plan systemic
treatment using chemotherapy drugs. There is a lot of research
interest in newer drugs for this group of cancers.
PARP inhibitors
Targets for therapy - EGF receptor ,aB-crystallin and cyclin
E.
HER2 type
These have a poorer prognosis and are associated with higher
risk of early recurrence and metastases.
Breast Care Book
Comprehensive Information and
advice on all aspects
of breast care.
Meet the Surgeon
Trevor Smith MBChB FCS