Numerical aberrations of chromosomes 7, 9 and 17 in 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 regarding histopathology, clinical outcome and etiology, the underlying genetic effects of these 2 tumor types may also be different. We compared numerical aberrations of chromosomes 7, 9 and 17 in bilharzial squamous cell carcinoma, and bilharzial and nonbilharzial transitional cell 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 51 women with a mean age of 54.8 years (range 28 to 83). Of the 220 patients 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 in situ hybridization cystectomy specimens were evaluated for numerical aberrations of chromosomes 7, 9 and 17, and p53 detection was performed by immunohistochemistry. Results: Aberrations of chromosome 7 were observed in 79% of the bilharzial squamous cell carcinoma specimens, and 100% and 93.2% of bilharzial and nonbilharzial transitional cell carcinoma specimens, respectively (p = 0.00011). Aberrations of chromosome 9 were seen in 92% of squamous cell carcinoma specimens but in only 52.4% and 60.9% of bilharzial and nonbilharzial transitional cell carcinoma, respectively (p <0.00001). Aberrations of chromosome 17 were found in only 29% of squamous cell carcinoma specimens, compared to 83.6% and 84.7% aberrations of chromosome 17 in both transitional cell carcinoma groups, respectively (p <0.00001). The p53 over expression was similar in all 3 tumor types with 82% for squamous cell carcinoma, and 73.7% for bilharzial and 81.3% for nonbilharzial. transitional cell carcinoma (not significant, p = 0.5285). Conclusions: Our data show clear differences between chromosomal patterns of invasive bilharzial squamous cell carcinoma and invasive bilharzial or nonbilharzial transitional 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 oncogenesis of squamous cell and transitional cell carcinoma at the cytogenetic level as suggested by molecular studies.