Table 2.

Diagnostic performance of serum HER2 extracellular domain for tissue HER2 status at different cut-off values

Cut-off values (ng/mL)	True positive	False positive	True negative	False negative	Sensitivity (95%CI)	Specificity (95%CI)
15.001	23	35	165	16	0.59 (0.42-0.74)	0.83 (0.77-0.88)
24.752	21	15	185	18	0.54 (0.37-0.70)	0.93 (0.88-0.96)

¹Value recommended by FDA for breast cancer;

²Value determined by Youden’s index in ROC plot.