Table 1 Breast cancer subtype characterization and immune-related reclassification

Luminal A

ER⁺ and/or PR⁺, HER2⁻, and low Ki67

30–70% prevalence;

Tumor grade of 1 or 2

Endocrine therapy;

Aromatase inhibitors;

Standard chemotherapy;

Best prognosis of the four tumor types

Further research required

Luminal B

ER⁺ and/or PR⁺ and HER2^{+ or –};

High Ki67

10–20% prevalence;

Often younger age of diagnosis;

Higher grade and worse prognosis than luminal A

Endocrine therapy; Aromatase inhibitors;

Standard chemotherapy

Further research required

HER-2-enriched

ER⁻, PR⁻, and HER2⁺

5–15% prevalence; Likely to be high grade and LN+; Poor prognosis

Trastuzumab; Pertuzumab; T-DM1; lapatinib; TKIs; anthracycline-based chemotherapy

SR +/−; CC +/−; IR +/−; ECM +/− (Teschendorff et al. [22]); (Staaf et al. [21])

Triple negative/basal-like

ER⁻, PR⁻, HER2⁻

15–20% prevalence;

High grade and proliferation;

Often BRCA-1 related;

Radiation; Platinum-based chemotherapy; PARP inhibitors

CC +/−; IR +/−; ECM +/− (Teschendorff et al. [22]);

BL1, BL2, IM, MSL, LAR (Lehmann et al. [23])