The association between circulating IGF-1 and pCR has been investigated by Tong et al. in a retrospective clinical study, where they found that a low IGF-1 level was related with a higher pCR rate (OR = 3.93, P = 0.031) in trastuzumab treated HER2 positive breast cancer patients14. The gene discussed is ERBB2; the disease is breast cancer.