Indeed, morphologically normal epithelium adjacent to tumour harbours a higher level of genetic instability relative to reduction mammoplasty tissue, particularly when normal is within 1 cm of tumour; furthermore normal epithelium from cancer-free patients who carry a pathogenic germline mutation in BRCA1 or BRCA2 also acquire an elevated level of chromosomal instability compared to controls [57,62,63,64,65,66]. This evidence concerns the gene BRCA1 and cancer.