Molecular Subtypes of Breast Cancer
Luminal A Breast Cancer
- Hormone Receptor strongly positive (ER/PR)
- Her 2 Negative
- Ki 67 – low levels
They are low grade cancers, tend to spread slowly and have best prognosis.
Luminal B Breast Cancer
- Hormone receptor positive (ER/PR)
- Her 2 positive / negative
- Ki 67 – high levels
They grow slightly faster than Luminal A group and their prognosis is slightly worse
Triple Negative Breast Cancers
Triple negative BC (10-20%) do not express the hormone oestrogen, progesterone and HER2 receptors.
- Hormone receptor Negative
- Her 2 Negative
These cancers tend to be found in younger women and they grow and spread more quickly than other breast cancer types. This means that hormone therapy and
HER2 therapy are not helpful in treating these cancers and hence, chemotherapy is recommended for treatment.
These cancers can possibly be associated with the BRCA1 gene and therefore wound be recommended to be genetic counselling and testing.
Her 2 Positive Breast Cancer
- Hormone receptor negative (ER/PR)
- Her2 Positive
This Cancer grow faster than luminal A/B breast cancer and have the worst prognosis but they are often successfully treated with targeted therapies like Herceptin, Perjeta, Tykerb, Kadcyla
Ki-67
Ki-67 is a proliferation marker used to assess the rate of cell growth. It is a staining process that can measure the percentage of tumor cells that are positive. The more positive the cells are , the more quickly they are dividing and growing new cancer cells.
- Ki67 < 10% - Low
- Ki67 10-20% - Borderline
- Ki67 - >20% - High
This additional information together with other parameters will help make treatment decisions.