ERBB2 and breast carcinoma: Whereas, some RCTs such as I-SPY2 study showed that hazard ratios for oncologic outcomes following pCR were consistent across all subtypes of breast cancer.; hazard ratio of RFS in HR +/HER2 – tumors, 0.14 (95% CI, 0.03 - 0.55); hazard ratio of RFS in HR +/HER2 + tumors, 0.18 (95% CI, 0.05 - 0.41) (24).