Katchman BA et al. have reported that the overexpression of QSOX1 in pancreatic and breast tumors promotes cellular proliferation and invasion in vitro, that the expression of QSOX1 in breast tumors is correlated with tumor grade and that elevated QSOX1 mRNA in luminal B breast cancers is a predictive marker of poor prognosis [18, 19]. This evidence concerns the gene QSOX1 and breast cancer.