Table 1.

IRS, Her2-and IRS-classification scoring systems

Percentage of positive cells	X Intensity of Staining	= IRS (0 – 12)
0 = no positive cells	0 = no colour reaction	0 – 1 = negative
1 = < 10% of positive cells	1 = mild reaction	2 – 3 = mild
2 = 10-50% positive cells	2 = moderate reaction	4 – 8 = moderate
3 = 51-80% positive cells	3 = intense reaction	9 – 12 = strongly positive
4 = > 80% positive cells
IRS – points		IRS – classification
0 – 1		0 = negative
2 – 3		1 = positive, weak expression
4 – 8		2 = positive, mild expression
9 – 12		3 = positive, strong expression
Her2/neu Score	Reaction Format	Evaluation
0	No or less than 10% cells	Negative
1+	> 10% cells with minimal staining intensity	Negative
2+	> 10% cells with moderate staining intensity	Mildly positive
3+	> 10% cells with strong staining intensity	Strongly positive