CHEK2 and breast cancer: In addition to germline BRCA1/2 mutations, other genes of vital importance that are associated with breast cancer, such as Ataxia Telangiectasia Mutated (ATM), Partner and Localizer of BRCA2 (PALB2), and Checkpoint Kinase 2 (CHEK2), also belong to the DDR pathway and are involved in the response to DDR‐targeting therapies (13).