Association of specific chromosome alterations with tumour phenotype in posterior uveal melanoma

Posterior uveal melanomas have recurrent alterations of chromosomes 1, 3, 6 and 8. in particular, changes of chromosomes 3 and 8 occur in association, appear to characterize those tumours with a ciliary body component, and ha ve been shown to be of prognostic significance. The relevance of other chro mosome alterations is less certain. We have performed cytogenetic analysis on 42 previously untreated primary posterior uveal melanomas. Of interest w as the observation that as tumour size increased the involvement of specifi c chromosome changes, and the amount of chromosome abnormalities likewise i ncreased. Loss, or partial deletions, of the short arm of chromosome 1 were found to associate with larger ciliary body melanomas; typically, loss of the short arm resulted from unbalanced translocations, the partners of whic h varied. Trisomy of chromosome 21 occurred more often in ciliary body mela nomas, whilst rearrangements of chromosomes 6 and I I were primarily relate d to choroidal melanomas. Our results imply that alterations of chromosome 1 are important in the progression of some uveal melanomas, and that other chromosome abnormalities, besides those of chromosomes 3 and 8, are associa ted with ocular tumours of particular locations. (C) 2000 Cancer Research C ampaign.