Table 1. Immunoreactive score (IRS) of immunohistochemical staining.

Percentage of positive cells	Intensity of staining	IRS
0 (no positive cells)	0 (no reaction)	0–2 (negative)
1 (< 10% positive cells)	1 (mild reaction)	3–4 (mild)
2 (10–50% positive cells)	2 (moderate reaction)	5–8 (moderate)
3 (50–80% positive cells)	3 (intense reaction)	9–12 (strongly positive)
4 (> 80% positive cells)