CHEK1 and cancer: Given that preclinical and clinical data in this field accumulate continuously, based on current knowledge and taking into account some of the most common genomic alterations in cancers, we propose that for tumors with ATM mutations, ATR inhibitors could be used as radiosensitizers, in tumors with p53 mutations ATR, Wee1, and Chk1 inhibitors could be used as radiosensitizers, and in tumors with BRCA mutations, PARP inhibitors can be prioritized as radiosensitizers.