CGH and tumor stage

The total number of aberrations in all tumors studied (pT1-4) ranged from 0 to 20 per case (mean, 4.19). Gains (range, 0-13; mean, 3.58) were more frequent than deletions (range, 0-7; mean, 0.62)(Table 1). Eight tumors had no detectable aberrations. Two tumors had single aberrations (7q+ and 9q+ respectively).

Stage pT1. pT1 tumors had an average number of 3.25 aberrations per case, ranging from 0 to 9). There were 0.13 deletions (range, 0-2) and 3.13 gains (range, 0-9). Seven out of 16 tumors (43.75%) had no detectable aberrations. No tumor showed a single aberration. No deletion was repeatedly found. Gain at 3q was the most frequent aberration (25%)(Table 2). Gains at 1q and 8q were found in 3 tumors (18.75%), while repeatedly in two tumors were gains at 2p, 2q, 3p, 6p, 6q, 8p, 10q, 12p, 12q, 16q, and 17q (12.5%). All aberrations of pT1 tumors are summarized in Fig. 1.

Stage pT2-4. pT2-4 tumors had higher number of aberrations than pT1 tumors (mean, 5.7; range 0-20). On average there were 1.4 deletions (range, 0-7) and 4.3 gains (range, 0-13). One tumor had no detectable aberrations (10%). Two tumors showed only one aberration (7q+ and 9q+ respectively). Repeatedly found aberrations were 17q+ (50%), 20q+ (40%), 5p+ (30%), 7q+ (30%), 15q+ (30%), 16q+ (30%), 9p- (20%), 3q+ (20%), 7p+ (20%), 12q+ (20%), and 20p+ (20%). All aberrations of pT2-4 tumors are summarized in Tables 1, 2 and Fig. 2.

Neither the total number of aberrations nor separately the number of deletions and gains reached statistically significant differences between pT1 and pT2-4 tumors (P=0.2030, P=0.0610, P=0.4350), although there was a trend towards increased genomic instability in muscle-invasive compared to minimally invasive bladder cancers. Most clear was the trend concerning the frequencies of deletions.

There was no significant difference between losses of none of the chromosomal regions. Gains at 5p and 20p were not found in pT1 tumors whereas they were repeatedly found in pT2-4 tumors (P=0.0198 and P=0.0626). The frequency of gains at 17q and 20q significantly increased in pT2-4 tumors compared to pT1 (P=0.0360 and P=0.0336). Summary of the results on affected chromosomal regions and tumor stage are shown in Table 2.

Table 1. Number of aberrations and tumor stage

a Aberrations per tumor (mean±SD)
b P=0.0610
c P=0.4350
d P=0.2030

CGH and tumor grade

The number of aberrations increased from grade 2 to grade 3 tumors (mean, 4.22; range, 0-20 for G2; and mean, 4.71; range, 0-10 for G3)(Table 3). The trend concerned both deletion and gains’ rate. However, the differences between G2 and G3 tumors were not significant neither in the number of deletions (P=0.8970) and gains (P=0.8410), nor in the total number of chromosomal aberrations (P=0.8210).

Table 2. Specific genomic alterations and tumor stage

^a λ² test