CHEK2 and cancer: When homologous recombination repair genes BRCA1/2, ATM, PALB2, and CHEK2 are inactive, a variety of error-prone and non-conservative DNA repair pathways are used, increasing the incidence of cancer and worsening its prognosis while also causing genomic instability (Castro and Eeles, 2012; Amsi et al., 2020).