[Tumor markers in testicular cancer].

In patients with testicular germ cell tumours, determination of both human chorionic gonadotropin (hCG) and alphafetoprotein (AFP) is mandatory for the diagnosis and the follow-up under treatment. Most so-called hCG-beta kits measure hCG plus the free beta-subunit. This seems to be important, as selectively elevated levels of hCG-beta have been found in some seminoma patients. Diagnosis and follow-up must always be done with the same method, because the kits available differ in specificity. AFP determination with poly- or monoclonal antibodies gives comparable results. A short-lasting increase in hCG and/or AFP during chemotherapy is due to cell necrosis and is not a sign of tumour progression. Highly elevated hCG levels at the beginning indicate a poor prognosis regardless of other parameters and should be borne in mind when decisions on treatment are made. Elevated levels of AFP mean that a pure seminoma cannot be present. In contrast, about 20% of seminoma patients have mildly elevated levels of hCG/hCG-beta, which are synthesized in syncytiotrophoblastic giant cells and only rarely in inconspicuous rounded seminoma cells. Serological hCG determinations are a more sensitive test than immunohistochemistry. The prognosis of this special form of seminoma tends to be similar to that of typical seminoma, and does not presently justify more aggressive treatment. No other highly sensitive and specific markers are available in seminoma. Nevertheless, placental alkaline phosphatase (PLAP) has some significance as a parameter for the follow-up in nonsmokers. False-positive values are found in about 20% of heavy smokers, which reduces the specificity of this test. The sensitivity is said to be about 90%. Lactate dehydrogenase (LDH) is significantly elevated, especially in the presence of advanced tumours. The specificity of LDH is low, as a variety of non-malignant diseases and minimal tissue damage can lead to pathologic serum levels. Nevertheless, LDH is of some value in the follow-up of marker-negative patients and can indicate a persistent tumour or a recurrence. Some authors have found evidence that initially elevated LDH may be an independent prognostic factor. The isoenzyme LDH 1 is easily determined, shows elevated levels in the presence of testicular germ cell tumours even if the total LDH is normal and is possibly more specific. However, the data presently available cannot yet justify its general application.(ABSTRACT TRUNCATED AT 400 WORDS)