Cytogenetic study of four cancers of the prostate.

We cytogenetically studied four cases of adenocarcinoma of the prostate. All tumors were moderately differentiated or well-differentiated, with different degrees of invasion. One tumor with microscopic seminal vesicle invasion and lymph node metastasis (tumor 4) had trisomy 7 as a sole clonal abnormality, suggesting that this is a primary change in some prostatic tumors. Although only normal karyotypes were observed in the other three tumors, several nonclonal changes were evident. Monosomy 9 or deletion of the long arm of 9 was observed in at least one cell in the three tumors without trisomy 7. Furthermore, in one of these tumors (tumor 3, moderately differentiated), several rearrangements (five of 26 cells) were observed, two of which had a common breakpoint at 15q11. Although complex chromosome changes including del(10q) and del(7q) have been described in prostatic tumors, they were not observed in the four tumors studied. This is the first report of a prostate tumor with trisomy 7 as a single clonal chromosome abnormality.