Table 1.

Breast cancer classification, characterization, and model cell lines used in cancer treatment studies.

Subtype	Immunochemistry Markers	Systemic Therapy	Overview
luminal A	ER+ and/or PR+, HER2− and low Ki67	hormonal therapy	The most common subtype (50–60% of all cases) The relapse rate is the lowest in comparison to other types The recurrence is mainly in the bone Good prognosis for the patient Model cell lines: MCF-7, T47D
luminal B	HER negative: ER+ and/or PR+ or high Ki-67	hormonal therapy + chemotherapy	15–25% of breast cancer patients Relapse and recurrence occur more often than in the luminal B subtype Model cell lines: ZR-75
	HER positive: ER+ and any PR−, any Ki-67	hormonal therapy +anty-HER therapy + chemotherapy
HER2-enriched	ER−, PR−, HER2+	anty-HER therapy (humanized monoclonal antibodies and small kinase inhibitors ) + chemotherapy	20–30% of all cases of breast cancer Aggressive biological and clinical behavior Model cell lines: SK-BR-3, TUBO, EFM-192A, MDA-MB-361
basal-like	ER−, PR−, HER2−, CK5/6+, and/or EGFR+	chemotherapy	80% of basal-like subtype is triple-negative 15–20% of all cases of breast cancer Aggressive clinical behavior High rate of metastasis to the brain and lung Poor patient prognosis Model cell lines: MDA-MB-231,BT-549 (HTB-122),Crl-2324, Cal51