Mammaglobin a: a promising marker for breast cancer.

prognosis better than approaches using immunohistochemistry or fluorescence in situ hybridization (14 ). Increased serum HER-2/neu was detected in 12% of an overall breast cancer group (15 ) and provided independent prognostic information (12 ) that was superior to that from nodal involvement or hormone receptor status (15 ). Preoperative HER-2/neu concentrations in sera are significantly associated with the tissue marker (16 ). Thus, it seemed opportune to reduce further explorative studies on HER-2 serology to patients with HER-2/neu-overexpressing tissues. However, the main investigations were performed without selecting a subgroup of patients receiving trastuzumab therapy. We here present the first study of the longitudinal course of serologic HER-2/neu values in patients receiving trastuzumab. The HER-2/neu values were detected using a HER-2/ neu method on the Bayer Immuno 1 system. We confirmed that the data collection was fast and reproducible and could be incorporated into clinical routine easily (13, 17). Both serum and plasma are acceptable samples (18 ). Retrospectively, HER-2/neu testing indicated remission or disease progression in 74% of all cases. The sensitivity increased when the patients were restricted to metastatic breast cancer patients with visceral metastases. However, increased serum concentrations have been reported in benign diseases, including liver cirrhosis and hepatitis (19 ). One question that remains unanswered is whether the high sensitivity in breast cancer with liver metastases reflects an acquired liver dysfunction or whether HER-2/ neu-overexpressing breast tumor cells preferentially affect the liver rather than bones or the lung. Theoretically, the environment of bone and lung may induce a decrease in HER-2/neu expression. Taken together, HER-2/neu appears not to be a specific breast cancer marker (20 ), but because of its sensitivity, the serologic HER-2/neu determination may provide an additional tool to monitor trastuzumab therapy of breast cancer patients. Accordingly, serologic HER-2/neu determinations might be useful to improve outcome by avoiding time lost through ineffective regimens and by avoiding exacerbated side effects and unnecessary costs. In summary, plasma HER-2/neu parallels the clinical course in patients with metastatic breast cancer, especially in patients with visceral metastases.