CHEK2 and breast cancer: Results from the current study in MBC patients and our previous study in early BC patients regarding efficacy of chemotherapy and endocrine therapy do not explain the worse prognosis that has been reported for CHEK2 1100delC-associated compared with BC patients without this mutation (de Bock et al. 2004; Kriege et al. 2014; Schmidt et al. 2007; Weischer et al. 2012).