AKT1 and breast angiosarcoma: Meanwhile, another radiation-associated breast angiosarcoma in our cohort demonstrated a PIK3CA gain-of-function mutation; immunohistochemical studies in both radiation-associated and sporadic breast angiosarcomas have revealed the activation of the PIK3CA/Akt/mTOR pathway in a significant proportion of these tumors [28,29], making PIK3CA inhibitors a potentially relevant targeted therapy to explore.