A phase III clinical trial of aromatase inhibition (Anastrozole) with or without trastuzumab (TAnDEM study) among a subset of postmenopausal women with double, ER/PR positive and HER-2 positive cancers, found that the progression-free survival (PFS) was approximately 2 months on anti-estrogen alone and was doubled by the addition of trastuzumab [23]. This evidence concerns the gene ERBB2 and cancer.