In CHEK2 heterozygotes in both MyCode and UK Biobank, there was a significant excess risk of all cancers tested, including breast cancer (C50; OR=1.54 and 1.84, respectively), male genital organ cancer (C60-C63; OR=1.61 and 1.77 respectively), urinary tract cancer (C64-C68; OR=1.56 and 1.75, respectively) and lymphoid, hematopoietic, and related tissue cancer (C81-C96; OR=1.42 and 2.11, respectively). This evidence concerns the gene CHEK2 and cancer.