Table 3.

Marker detection and determination of molecular typing of breast cancer

Intrinsic molecular typing	IHC4-based molecular typing	Note
Luminal Type A	Luminal A-like ER/PR positive and PR high expression/HER2 negative Low Ki-67 proliferation index	It is recommended that the criteria of ER/PR expression, and Ki-67 proliferation index be reported in terms of the percentage of positive cells. The criterion of the Ki-67 proliferation index may vary in different pathological experimental centers, and 20–30% can be used as the threshold for determining high or low Ki-67, while, 20% can be the threshold for determining the level of PR expression a to further distinguish between luminal A and luminal B (HER2 negative).
Luminal Type B	Luminal B-like (HER2 negative) ER/PR positive HER2 negative and high Ki-67 proliferation index or low PR expression	The abovementioned luminal-like tumors that do not meet the conditions of the luminal A-like type can be regarded as the luminal B-like subtype
	Luminal B-like (HER2 positive) ER/PR positive HER2 positive (protein overexpression or gene amplification) Ki-67 in any state
ERBB2 + type	HER2 positive HER2 positive (protein overexpression or gene amplification) ER negative and PR negative
Basal-like type	Triple-negative (nonspecial invasive ductal carcinoma) ER negative PR negative-HER2 negative	The overlap between triple-negative breast cancer and basal-like breast cancer is approximately 80%, but triple-negative breast cancer also includes some special types of breast cancer such as medullary carcinoma (typical) and adenoid cystic carcinoma.

^a20% is used as the threshold for determining the level of progesterone receptor (PR) expression, which is currently supported by only one retrospective study (J Clin Oncol, 2013, 31: 203-209)