Table 1.

Three proxy intrinsic subtype classifications according to the clinicopathological surrogates by Cheang [5], Prat [6], and Maissonneuve [7]

PROXY 1 by Cheang et al. [5]	Luminal A: ER and/ or PR positive, HER2 negative, Ki67 low (Ki67 < 14%)
	Luminal B: ER and/ or PR positive, HER2 negative, and Ki67 high (Ki67 ≥ 14%)
PROXY 2 by Prat et al. [6]	Luminal A: ER positive/HER2 negative, PR > 20%, Ki67 < 14%
	Luminal B: ER positive/HER2 negative/Ki67 < 14%/PR ≤ 0% or ER positive/HER2 negative/Ki67 > 14%
PROXY 3 by Maissonneuve et al. [7]	Luminal A like: ER positive, HER2 negative, and at least one of the following conditions:
	*Ki67 low expression (< 14%) or
	*Ki67 intermediate expression (14–19%) and PR high expression (≥ 20%)
	Luminal B like: HER2 negative, ER positive, and at least one of the following conditions:
	*Ki67 intermediate expression (14–19%) and PR negative or low expression (< 20%) or
	*Ki67 high expression (≥ 20%)