In Reply Leong et al inquired about the potential role of personalized medicine in oncocardiology. They cited 2 older studies on 3 single-nucleotide polymorphisms (ABCC2 [rs8187710], CYBA [rs4673], and RAC2 [rs13058338]) associated with anthracycline-induced cardiotoxicity. This issue was recently reviewed by the Canadian Pharmacogenomics Network for Drug Safety Clinical Practice Recommendation Group.1 In this review, RARG (rs2229774), UGT1A6 (rs17863783), and SLC28A3 (rs7853758) were shown to have the “strongest and most consistent evidence for association with anthracycline-induced cardiotoxicity.”1 The 3 single-nucleotide polymorphisms cited by Leong et al were deemed to require additional validation. Interestingly, RARG (rs2229774) was shown to increase the transcription of topoisomerase IIβ.2 Thus, patients who developed anthracycline-induced cardiotoxicity are predicted to have higher topoisomerase IIβ expression. This is consistent with the new paradigm described in our review.3