CHEK2 and breast cancer: We found that CHEK2 mutations in patients with metastatic ER+/HER2− breast cancer, whether germ line or somatic, associate with shorter progression-free survival (average of 183 days) on frontline endocrine therapy relative to patients with CHEK2 wild-type disease (584 days) (MSKCC, P = 0.03) (fig.