Recent data also suggest that mutations of the DDR genes TP53, PPM1D and CHEK2, that are involved in clonal hematopoiesis, occur with increased frequency in cancer patients that were exposed to treatment, and in particular to platinum or topoisomerase II inhibitors or radiation therapy [171], indicating that DDR gene alterations improve the competitive fitness of the cells under these conditions. This evidence concerns the gene PPM1D and cancer.