about half of the HER2/ neu overexpressing cases (9.8%) did not show amplification by FISH.     ///    "even though a relationship with human epidermal growth factor receptor 2 (HER2/ neu ) status has been reported, other studies have shown that coincident centromere 17 (Cep17) amplification may be the cause of an overestimation of chromosome 17 polysomy in fluorescence in situ hybridization (FISH) testing. "    ///    "A total of 647 cases of invasive ductal breast cancer were collected and subjected to FISH analysis for HER2/neu gene and centromere 17 alteration, HercepTest for HER2/ neu protein expression, and routine immunohistochemistry for Ki-67 and hormone receptor status. "    ///    "(1) Centromere 17-altered cases are frequently HER2/ neu overexpressing but not amplified, resulting in HercepTest/FISH disagreement. "    ///    "To evaluate polysomy/amplification of Cep17 in invasive breast cancer with relation to proliferative activity (Ki-67), estrogen receptor, progesterone receptor, and HER2/ neu status, in an attempt to identify a subgroup of patients with a worse prognosis. "    ///    "Within this group, HER2/neu gene amplification was detected in 14.1% of cases, whereas HER2/ neu expression was scored 3+ in 20.1% of cases. "