Genetic imbalances revealed by comparative genomic hybridization in osteosarcomas

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Abstract
Osteosarcomas are the most frequent bone sarcomas. The molecular chromosomal aberrations in osteosarcomas were analyzed by comparative genomic hybridization (CGH). We studied 47 frozen tumors (41 primary samples, 6 relapses) in osteosarcoma patients registered in the Cooperative Osteosarcoma Study (COSS) protocol. Genomic imbalances were detected in 40 of 41 primary tumors and 6 of 6 relapsed tumors. Gains were more frequent than losses (ratio of 1.3:1). The median number of changes was 16 and 12 in primary and relapsed osteosarcomas, respectively. The median number of aberrations in primary high‐grade osteosarcomas (17.0) was significantly higher than in low‐ or intermediate‐grade osteosarcoma subtypes (3.0) (p = 0.038). The most frequent gains included 8q, 1p21‐p31 and 1q21‐q24, and the most frequent losses were 10q, 5q and 13q. High‐level gains were observed on 8q23‐q24, 17p13 and 1q21‐q24. A gain of 19p (p < 0.001) or loss of 9p (p = 0.027) was more frequent in poor responders than in good responders. Univariate analysis revealed that patients with primary metastases (p = 0.002), poor histologic responses (p = 0.005), high‐level gains of 19p (p = 0.012) or losses of 13q14 (p = 0.042) had significantly lower event‐free survival (EFS), whereas patients with a loss of 5q (p = 0.007) or a loss of 10q21‐22 (p = 0.017) had significantly higher EFS than patients without these aberrations. Multivariate analysis demonstrated that primary metastasis, loss of 13q14 and loss of 5q were independent prognostic factors. The findings of our study seem to be useful for evaluating the prognosis of patients and may finally lead to treatment strategies based on genetic background of osteosarcoma.