We therefore investigated the role of PTEN as prognostic marker in 115 metastatic Her-2 positive breast cancer patients who underwent trastuzumab-based therapy in the palliative setting, and then examined PTEN status and its association with clinical and histopathological parameters such as hormone receptor status, p53, MIB-1, IGFR, grading and clinical outcome (response rate, progression free survival (PFS), overall survival (OS)). The gene discussed is PTEN; the disease is breast carcinoma.