TP53 and breast cancer: TP53 mutations are rare in small and low-grade tumors, whereas the frequency increases with the size and grade of tumors.54 Furthermore, breast cancer patients with somatic TP53 mutations have shorter disease-free survival compared with patients with wild-type TP53, and respond less well to chemotherapy, antihormonal therapy or radiotherapy.55, 56 In future studies it has to be analyzed whether elevation of miR-519a-3p in TP53-mutated patients is directly regulated by p53 and/or other factors.