Comparative genomic hybridization analysis reveals new different subgroups in early-stage bladder tumors.
OBJECTIVE
To classify bladder tumors according to their genomic imbalances and evaluate their association with patient's outcome.


METHODS
Sixty-three superficially and minimally invasive bladder tumors were analyzed by conventional comparative genomic hybridization. Subtelomeric screening in 15 of these tumors was performed by multiplex ligation-dependent probe amplification.


RESULTS
Losses of 9q and 9p (32% and 25% of all cases, respectively) as well as gains of chromosomes Xq and Xp (28% and 25%, respectively) were the most frequent chromosome imbalances. Losses of 8p and gains in 1q and 8q were detected in >20% of cases. Tumors were classified into 3 groups according to their individualized pattern of gains and losses. The largest group was characterized by few chromosome imbalances, presenting 77% and 49% of the Ta and T1 tumors, respectively. Another group characterized by chromosomal gains, was composed of equal number of Ta and T1 tumors, with +1q and +17q gains being the most common imbalances. A minority group was characterized by chromosomal losses on 11q, 5q, and 6q. The multiplex ligation-dependent probe amplification study showed good correlation with comparative genomic hybridization results. With regard to the biological significance of this classification, a remarkable fact is that this minority group composed mainly of T1 tumors, showed a significant decrease in patient overall survival.


CONCLUSIONS
Our data suggest that superficial carcinomas of the bladder can be subdivided into a larger number of subclasses than had previously been expected. Our results also demonstrate a decreased survival among patients whose tumors show more genomic losses than gains.
Prat
Esther
E
Institut de Biotecnologia i Biomedicina and Department de Biologia Cel.lular, Fisiologia i Immunologia, Universitat Autònoma de Barcelona, Barcelona, Spain.
del Rey
Javier
J
Ponsa
Immaculada
I
Nadal
Marga
M
Camps
Jordi
J
Plaja
Alberto
A
Campillo
Mercedes
M
Algaba
Ferran
F
Gelabert
Antoni
A
Miró
Rosa
R
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D055028:Comparative Genomic Hybridization; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D001749:Urinary Bladder Neoplasms / Q000145:classification* / Q000235:genetics* / Q000473:pathology