TP53 and therapy-related myeloid neoplasm: Therefore, there are at least two mechanisms by which TP53 mutations occur in t-MN: (1) TP53 clones are present in patients before the onset of chemotherapy as CHIP, and chemotherapy promotes clonal selection of pre-existing clones; (2) TP53 mutant HSCs or the chemotherapy itself may directly induce DNA damage and leukemogenic TP53 lesions [56].