carriers of the brca1 gene , like hollywood star angelina jolie , can reduce their risk of death once they have been diagnosed with breast cancer by more than 60 per cent .
miss jolie , 39 , had the procedure , known as an oophorectomy , in march .
two years before , she had a double mastectomy as she carries the brca1 gene variant which dramatically raises the risk of developing both breast and ovarian cancer .