Table 1. The applicable crowd, advantages and disadvantages and NCCN Guidelines Recommendation of gene expression assays.

Model	Applicable crowd	Advantages	Disadvantages	NCCN guideline recommendations
21-GA	ER (+), node (+/−)	(I) Predict the 10-year risk of DR and LRR; (II) Predict the benefit of chemotherapy and guide patients’ chemotherapy decision	(I) No recognition of the risk of late-stage events; (II) Lack of guiding significance for the chemotherapy decision in patients with intermediate-RS; (III) Lack of effective evidence to guide regional radiotherapy decision-making; (IV) High cost	(I) Class 1 evidence for patients with node (−) and postmenopausal patients with node (1–3+); (II) Class 2A evidence for premenopausal patients with node (1–3+)
70-GS	ER (+/−), node (+/−)	(I) Predict the 5-year risk of DM and LRR; (II) Guide chemotherapy decisions in patients with intermediate-RS; (III) Instruct chemotherapy decisions in patients with high-risk clinical features and low-risk gene-expression profiles	(I) Fail to effectively predict late tumor events; (II) The cost-effectiveness was observed in patients with high-risk clinical features, but fail in those with negative nodes; (III) Fresh frozen tissue samples require higher quality; (IV) High cost	(I) Class 1 evidence for patients with node (−) and patients with node (1–3+)
PAM50	All patients	(I) Assign an intrinsic subtype to patients; (II) Predict the 10-year risk of DR and LR; (III) Instruct the prolonged endocrine therapy for 5–10 years after diagnosis; (IV) Better distinguish intermediate- and high-risk groups than 21-GA; (V) Can be performed in any qualified pathology laboratory	(I) Lack of effective evidence to guide chemotherapy decision; (II) Cannot predict the benefit of radiotherapy, and need further verification; (III) High cost	(I) Class 2A evidence for patients with node (−) and patients with node (1–3+)
Endopredict	ER (+), HER2(−)	(I) Combine genomics and clinicopathological information; (II) Predict the early- and late-stage risk of DR and LR; (III) Instruct the decision-making of prolonged endocrine therapy and combining chemotherapy; (IV) Portable prognostic platform and sample type	(I) Lack of effective evidence on predicting the benefit of chemotherapy; (II) Not suitable for customized local treatment regimens	(I) Class 2A evidence for patients with node (−) and patients with node (1–3+)
BCI	ER (+), node (+/−)	(I) Unique advantages in late-stage prognostic prediction; (II) Important guiding significance for prolonged adjuvant endocrine therapy	(I) Lack of effective evidence on predicting the benefit of chemotherapy	(I) Class 2A evidence for patients with node (−) and patients with node (1–3+)

ER (+), estrogen receptor positive; ER (+/−), estrogen receptor positive or negative; HER2 (−), human epidermal growth factor receptor 2; node (+/−), lymph node positive or negative; node (1–3+), 1 to 3 positive lymph nodes; 21-GA, 21-gene assay; 70-GS, 70-gene signature; DR, distant recurrence; LRR, local regional recurrence; LR, local recurrence; BCI, breast cancer index; NCCN, National Comprehensive Cancer Network.