Table A1.

Mu opioid receptor expression score.

Positivity Percentage	Staining Intensity
	No Staining	Weak	Moderate	Strong
Negative (< 5%)	0	1	2	3
Sporadic (5%–25%)	0	2	3	4
Focal (25%–50%)	0	3	4	5
Diffuse (> 50%)	0	4	5	6