We found that mALN-to-background andmALN-to-latissimus dorsi muscle ratios for [99mTc]Tc-(HE)3-G3 uptake 4 h afterits administration may be used for typing of the HER2/neu status in mALNs ofbreast cancer patients (p < 0.05, Mann–Whitney test).In that case, sensitivity and specificity for the mALN-to-background ratio wereidentical at 80%, with the threshold value being > 12.25. This evidence concerns the gene ERBB2 and cancer.