Examples are variants in ABCB1 that can predict toxicity and response to chemotherapy in breast cancer (Xiao et al. 2020) and ABCG2 and ABCC10 variability that associates with tyrosine kinase inhibitor and taxane toxicity in non-small cell lung cancer (Noguchi et al. 2014; Sone et al. 2019). This evidence concerns the gene ABCG2 and breast cancer.