Chromosomal imbalances associated with carcinoma in situ and associated testicular germ cell tumours of adolescents and adults

Carcinoma in situ (CIS) or intratubular germ cell neoplasia is generally co nsidered the precursor lesion of adult testicular germ cell tumours (TGCT). The chromosomal imbalances associated with CIS and the corresponding semin oma (SE) or nonseminoma (NS) have been determined by comparative genomic hy bridization (CGH) analysis of microdissected material from seven cases. Sig nificantly, the CIS showed no gain of 12p material whereas in the invasive components of all cases gain of 12p was found, in 2 cases associated with a mplification of the 12p11.2-12.1 region. Interphase fluorescence in situ an alysis was consistent with this and provided evidence for the i(12p) or 12p 11.2-12.1 amplification in the SE and NS but not in the corresponding CIS. This suggests a role for these changes in progression of CIS to invasive te sticular cancer or progression of the invasive disease. Other imbalances su ch as gain of material from chromosomes 1, 5, 7, 8, 12q and X and loss of m aterial from chromosome 18 were frequently identified (> 40% of cases) in t he CIS associated with both SE and NS as well as in the invasive components . Loss of material from chromosome 4 and 13 and gain of 2p were more freque ntly found in the invasive components. The results shed light on the geneti c relationship between the non-invasive and invasive components of testicul ar cancer and the stage at which particular chromosomal changes may be impo rtant. (C) 2001 Cancer Research Campaign http://www.bjcancer.com.