The driver role of RRAS2 overexpression in mice is paralleled by the finding of overexpression of RRAS2 in more than two thirds of patients’ samples, of which, those from young parous women and of TNBC type are the ones with highest expression of RRAS2. Finally, we found an overrepresentation of tumors with homozygosity for the alternate C allele at SNP rs8570 position and an increased number of copies of the RRAS2 gene in both tumoral and healthy tissue of BC patients. This evidence concerns the gene RRAS2 and breast cancer.