. Author manuscript; available in PMC: 2020 Feb 1.

Published in final edited form as: Breast Cancer Res Treat. 2017 Aug 8;166(2):613–622. doi: 10.1007/s10549-017-4421-3

Table 2.

Mean Ki67 score in 2,555 incident invasive breast tumors by molecular subtype defined with tumor grade, Nurses’ Health Study, 1976–2006

	Breast Cancer Molecular Subtype^a
	Luminal A	Luminal B	HER2-enriched	Basal-like	Unclassified
	n=1287 (50%)	n=738 (29%)	n=177 (7%)	n=268 (11%)	n=85 (3%)	p-value^b
Mean Ki67 score, % (SD)	8.9 (10.6)	12.6 (13.9)	17.9 (19.7)	20.6 (18.5)	9.5 (10.3)	<0.0001

Molecular breast cancer subtypes defined using ER, PR, HER2, EGFR, CK5/6 and tumor grade

Kruskal-Wallis test