TP53 and neoplasm: The tumor suppressor gene TP53 is mutated in 30–40% of breast tumors, with variation in mutation frequency by intrinsic subtype and race.1–14 Up to 80% of basal-like and 70% of human epidermal growth factor 2-enriched (HER2-enriched) breast tumors harbor TP53 mutations, which commonly include nonsense and frame shift alterations.1 Mutations occur at much lower frequencies among Luminal A (12–23%) and Luminal B (15–29%) tumors1,2,9,13–15 and are primarily missense mutations in form.