Table 5.

Agreement between three biomarker IHC-based and intrinsic subtypes: impact of using a 10% versus 1% threshold to define estrogen receptor (ER) and progesterone receptor (PR) positivity

IHC subtypePAM50 intrinsic subtype
IHC definitionLuminal ALuminal BHER2-enrichedBasal-likeTotalSensitivitySpecificityAccuracy
1% ER positivity threshold
 Luminal AER+, PR > 20%, HER2−122 (76)49 (57)10 (14)8 (6)18976%77%77%
 Luminal BER+, PR ≥ 1%, HER2+ or ER+, PR ≤ 20%, HER2−38 (24)36 (42)30 (43)28 (21)13242%73%67%
 HER2-enrichedER−, HER2+0 (0)0 (0)19 (27)5 (4)2427%99%86%
 Basal-likeER−, PR < 1%, HER2−0 (0)1 (1)11 (16)90 (69)10269%96%88%
 Total1608670131447
IHC definitionLuminal ALuminal BHER2-enrichedBasal-likeTotalSensitivitySpecificityAccuracy
10% ER positivity threshold
 Luminal AER+, PR > 20%, HER2−122 (76)49 (57)10 (14)8 (6)18976%77%77%
 Luminal BER+, PR ≥ 10%, HER2+ or ER+, PR ≤ 20%, HER2−37 (23)34 (40)18 (26)5 (4)9440%84%75%
 HER2-enrichedER−, HER2+1 (1)0 (0)26 (37)6 (5)3337%98%89%
 Basal-likeER−, PR < 10%, HER2−0 (0)3 (3)16 (23)112 (86)13186%94%91%
 Total1608670131447