NF1 and breast cancer: NF1 loss of function is also more commonly detected in endocrine-resistant and metastatic breast cancer cases (Meric-Bernstam et al., 2014; Yates et al., 2017; Razavi et al., 2018; Bertucci et al., 2019; Sokol et al., 2019; Pearson et al., 2020).