MARKERS VAN KIEMCELTUMOREN VAN DE TESTIS

Among solid tumors, testicular germ cell tumors have served as role models in the development and application of tumor markers. The routinely measured 'specific' serum markers: human chorionic gonadotrophin (HCG; trophoblastic elements), alpha fetoprotein (AFP; yolk sac tumor) and placental like alkaline phosphatase (in particular seminoma) can be demonstrated immunohistochemically as well. TRA-1-60 is a new serum tumor marker, which in the context of germ cell tumors is specific for embryonal carcinoma, and is elevated in 60-70% of the cases with normal levels of AFP and HCG. The serum levels lactate dehydrogenase-1 (LDH-1), a marker for seminoma and nonseminoma, is correlated with the number of copies of the short arm of chromosome 12, and thus with the dose of the gene coding for this enzyme, which maps on 12p. Eighty percent of testicular germ cell tumors have one or more copies of a specific chromosomal marker: isochromosome 12p, composed of two short arms and the centromeric region of chromosome 12. Numerical and structural abnormalities of chromosome 12, among which i(12p), seem to be important in the genesis of germ cell tumors. Specific DNA sequences in the breakpoints in chromosome 12, when isolated, could play an important role in 'molecular staging' of testicular germ cell tumors.