Cytogenetics of testicular germ cell tumors of adults

In this article, not intended to be a review of the literature, we present our view about the oncogenesis, pathogenesis and tumor progression of testicular germ cell tumors of adults. This view is based on our cytogenetic analyses df primary testicular germ cell tumors (seminomas and non-seminomas), non-invasive precursor lesions (carcinoma in-situ), and metastatic lesions after chemotherapy (residual mature teratoma). We found that the chromosomal pattern of testicular germ cell tumors of adults is characterized by a chromosome number in the triploid range, amplification of the short arm of chromosome 12 (by i(12p)-formation or of her structural abnormalities of chromosome 12); and over-representation of specific chromosomes (e.g. 7, 8, 12, 21, and X) and under-representation of others (e,g. 11, 13, 18, and Y). This strongly suggests that polyploidization, 12p amplification, and over- and under-representation of specific chromosomes are important steps in the oncogenesis and/or progression of testicular germ cell tumor, i(12p)-formation and over- and under-representation of chromosomes already occurs in carcinoma in-situ. This may suggest that most chromosomal changes related to tumor progression take place very early in tumor development. The resulting highly abnormal chromosomal pattern is retained during metastasis and, in the case of residual mature teratoma, after chemotherapy. Additionally, our cytogenetic data are in accordance with a pathogenetic model of testicular germ cell tumors suggesting that seminomas and non-seminomas are strongly related with a common origin and a single neoplastic pathway.