The vast majority of breast cancers are ER positive and can be classified into 2 molecular subtypes: luminal A and luminal B.
Compared with their luminal B counterparts, luminal A tumors generally are lower grade, have higher expression of estrogen-related genes, have a better prognosis, and are more sensitive to endocrine therapy.
A subtype of breast cancer that composes at least half of all new breast cancer diagnoses.
Patients with luminal A tumors have a better disease-free survival if progesterone receptor is greater than 20%, and generally defined as ER positive, PR greater than 20%, HER2 negative and KI-67 less than 14%.
Has a low recurrence rate based on gene based assays.
Among women, at least 55 years of age with a T1N0 grade, one or two luminal A breast cancer, treated with breast conserving surgery and endocrine therapy alone, the incidence of local recurrence at five years was low with omission of radio therapy (Whelan TJ).
Luminal B tumors are ER positive, HER2 positive or negative and at least one of thefollowing: KI-67 20% or greater, PR negative or less than 20% and high recurrence rate based on multiple gene expression assay.