Nonetheless, confirmation that the association between the rs11212617 C allele and the benefit of adding metformin in terms of clinical outcomes (pCR, IDFS, OS) is equivalent in neoadjuvant and adjuvant treatments of non-diabetic HER2+ BC patients should be viewed as strong-hypothesis-generating data that warrants replication in a prospective trial to replicate if the pharmacogenomic profile of the rs11212617 SNV genotype should definitely deserve consideration as a predictive biomarker to inform the use of metformin in non-diabetic BC patients. The gene discussed is ERBB2; the disease is breast cancer.