ERBB2 and breast cancer: In the 8th cancer staging manual by the American Joint Committee on Cancer 2017 update, 5 multi-gene panels (Oncotype DX, MammaPrint, EndoPredict, Prosigna/PAM50, and the Breast Cancer Index; Table 2) are considered to be stage modifiers, reclassifying low-risk hormone receptor-positive, HER2-negative, and lymph node-negative tumors of any size into Stage I, the same prognostic category as T1a-T1bN0M0 [81].