PIK3CA and breast cancer: TP53, the tumor suppressor (Baker et al., 1989; Rivlin et al., 2011), PIK3CA kinase (Karakas et al., 2006), and the epidermal growth factor receptor ErbB-2 and EGFR (Tebbutt et al., 2013), reported in multiple subtypes of cancer, are localized at the bottom right corner of the gene-variant map, suggesting the contribution of these genes to cancer in general with lower specificity to breast cancer compared to BRCA1 and BRCA2 (Figure 1).