HER2-Protein (Serum (s))

The determination of the human epidermal growth factor receptor HER2/neu in tissue samples of patients with mammary carcinoma has been established in primary diagnostics for several years. If it is overexpressed by tumour cells, about one third of patients affected benefit from a therapy with the antibody trastuzumab (Herceptin).

The determination in the serum additionally offers the possibility of estimating the prognosis and allows for a follow up of the therapy with Herceptin. Using the serum test for the initial therapy decision is currently under discussion.

Initial studies show that HER2/ neu levels in the serum correlate with the progression-free survival under chemotherapy and probably also with the total survival time.

In this respect it could also be shown that the HER2/ neu serum concentrations are not only of prognostic relevance in patients with metastasing mammary carcinoma, but also for the localised primary finding. Patients with HER2/ neu positive results partly show a significantly higher tendency to forming metastases than those with HER2/ neu negative results.

They develop pulmonary and liver metastases more often. Decreasing serum levels under Herceptin therapy are a clear sign of therapy success. If the concentrations remain constant or even increase, the patient is not responding to the antibody therapy.

The test is highly specific and only shows slightly increased serum levels in the case of very few benign and malignant (non-mammary carcinoma) diseases. Concentrations up to approx. 20 - 30 µg/l can be measured especially in the case of liver dysfunction.

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