CHEK1 and small cell lung carcinoma: In particular, we found germline POLE, POLD1, RAD51 paralog B (RAD51B), checkpoint kinase 1 (CHEK1) and ATM pathogenic variants in BR and R SCLC patients, whereas NSCLC BR/R patients harbored germline pathogenic variants in BARD1 and ATM (Figure 4) [8,18,19,20,21].