Monitoring Serum HER-2 to Help Manage Metastatic Breast Cancer Patients The HER-2 ELISA is a simple, non-invasive blood test that can be used as a clinical tool for monitoring and managing patients with MBC when used in conjunction with other diagnostic procedures. When serum values are equal to or greater than 15 ng/mL, the test can be used to monitor a patient’s HER-2 status. The increase or decrease in serum HER-2 levels have been shown to parallel the clinical course of disease regardless of a patient’s treatment regimen [6-8]. As shown in Figure 1 and 2 increasing levels in serum can reflect disease progression while decreasing levels can reflect treatment response or stable disease [8-17]. Monitoring the changes of serum HER-2 levels can help manage treatment of MBC patients. A normal serum HER-2 level is less than 15ng/ml and an elevated level ( above normal) is 15 ng/ml or greater. The serum HER-2 ELISA test is for use in the follow-up and monitoring of MBC patients whose first serum HER-2 blood test is equal to or above 15ng/ml. When the first blood level is elevated, physicians can begin monitoring the HER-2 level routinely. Each time a HER-2 blood level is tested, the result will be compared to the last test result. In our clinical study, an increase of 20% or greater from the previous visit was reflective of disease progression. If the change was less than a 20% increase from the previous visit it was reflective of a lack of disease progression during therapy. Physicians can use this information, together with other clinical tests, to manage patient treatment.