The vast majority of NF1 cases reported with breast cancer were known to have NF1 prior to breast cancer diagnosis.6,7 Furthermore, driver NF1 pathogenic variants have been identified in the Cancer Genome Atlas and from NF1 patients are associated with higher tumour grade and Human Epidermal Growth Factor Receptor 2 (HER2) overexpression,8,9 further evidence against a chance association. This evidence concerns the gene ERBB2 and breast cancer.