Five BC specific PIK3CA alterations (c.1035T>A, p.Asn345Lys; c.1633G>A, p.Glu545Lys; c.3140A>G, p.His1047Arg; c.3140A>T, p.His1047Leu; c.3145G>C, p.Gly1049Arg), reported as predictors of response to PI3Kα-specific inhibitor combined with estrogen receptor antagonist, were identified in six (40%) MBCs (Table 2). Here, PIK3CA is linked to breast cancer.