CYTOGENETICS OF 158 PATIENTS WITH REGIONAL OR DISSEMINATED MELANOMA -SUBSET ANALYSIS OF NEAR-DIPLOID AND SIMPLE KARYOTYPES

We report on the cytogenetic analyses of 158 cases of metastatic malig nant melanoma, comprised of 63 cases with regional disease (RD) and 95 cases with distant (metastatic) disease (DD). Clonal structural abnor malities were identified in 126 (80%) cases and were significantly inc reased (< 0.01 after adjusting for multiple comparisons) on chromosome s fin order of frequency of involvement) 1, 6, 7, 11, 9, and 3. Cluste ring of breakpoints occurred at 1p36, 1p22-q21, 6p11-q21, 9p, 11q23-qt er, 13p (especially for cases with DD), and 19q13. The most common clo nal numerical abnormalities, in a subset of 49 near-diploid cases were -10, -22, -9, +7, -19, and -Y. Analysis of chromosome segment gains a nd losses (CSRP) showed frequent loss of chromosomes 6 and 10, followe d by equal rates of involvement of chromosomes 1, 7, and 9. Whole or s egmental losses of chromosome 9 (especially 9p) correlate well with re cent molecular genetic studies identifying putative suppressor genes, and are also likely important genetic abnormalities. However, based on the frequency of abnormalities in this large series of metastatic mel anomas, it is likely that structural abnormalities of 1 and 6, and -10 are important in the pathogenesis of sporadic advanced melanoma.