NUMERICAL ABERRATIONS OF CHROMOSOME-7, CHROMOSOME-9 AND CHROMOSOME-17IN SQUAMOUS-CELL AND TRANSITIONAL-CELL CANCER OF THE BLADDER - A COMPARATIVE-STUDY PERFORMED BY FLUORESCENCE IN-SITU HYBRIDIZATION

Purpose: Since squamous cell differs from transitional cell cancer reg arding histopathology, clinical outcome and etiology, the underlying g enetic effects of these 2 tumor types may also be different. We compar ed numerical aberrations of chromosomes 7, 9 and 17 in bilharzial squa mous cell carcinoma, and bilharzial and nonbilharzial transitional cel l carcinoma by fluorescence in situ hybridization, and correlated the findings to p53 positivity of the 3 tumor types.Materials and Methods: Cystectomy for invasive bladder cancer was performed in 169 men and 5 1 women with a mean age of 54.8 years (range 28 to 83). Of the 220 pat ients 100 (45.4%) had histologically verified bilharzial squamous cell carcinoma, 61 (27.7%) bilharzial transitional cell carcinoma and 59 ( 26.8%) nonbilharzial transitional cell carcinoma. Using fluorescence i n situ hybridization cystectomy specimens were evaluated for numerical aberrations of chromosomes 7, 9 and 17, and p53 detection was perform ed by immunohistochemistry. Results: Aberrations of chromosome 7 were observed in 79% of the bilharzial squamous cell carcinoma specimens, a nd 100% and 93.2% of bilharzial and nonbilharzial transitional cell ca rcinoma specimens, respectively (p = 0.00011). Aberrations of chromoso me 9 were seen in 92% of squamous cell carcinoma specimens but in only 52.4% and 60.9% of bilharzial and nonbilharzial transitional cell car cinoma, respectively (p <0.00001). Aberrations of chromosome 17 were f ound in only 29% of squamous cell carcinoma specimens, compared to 83. 6% and 84.7% aberrations of chromosome 17 in both transitional cell ca rcinoma groups, respectively (p <0.00001). The p53 over expression was similar in all 3 tumor types with 82% for squamous cell carcinoma, an d 73.7% for bilharzial and 81.3% for nonbilharzial. transitional cell carcinoma (not significant, p = 0.5285). Conclusions: Our data show cl ear differences between chromosomal patterns of invasive bilharzial sq uamous cell carcinoma and invasive bilharzial or nonbilharzial transit ional cell carcinoma but similar frequencies of p53 over expression in all 3 tumor types. However, aberrations of chromosome 9 were observed in all analyzed groups, which confirms the 2 pathways in the oncogene sis of squamous cell and transitional cell carcinoma at the cytogeneti c level as suggested by molecular studies.