Chromosomal and genetic imbalances in synovial sarcoma detected by conventional and microarray comparative genomic hybridization

Purpose: To analyze the relationship between chromosomal instabilities and clinicopathological factors in synovial sarcoma (SS). Methods: Twenty-two fresh-frozen SS were analyzed by metaphase comparative genomic hybridization (CGH). Additional microarray CGH was performed in 13 cases. Results: Fourteen patients with SYT–SSX1 rearrangements and nine patients with biphasic tumor subtypes had better prognosis than the eight patients with SYT–SSX2 rearrangements and 13 patients with monophasic subtypes, respectively. Gains (average 3.0) were more frequent than losses (average 1.0). Frequent gains were identified on chromosomal regions 2, 6q, 7, 8q, 12, 17q, 18q, and 21q, whereas frequent losses were over-lapped on chromosomes 1p31–p35, 3p, 6q, 16, and 17p. High-level gains were observed on chromosomes 1q21–q31, 7, 8, 12, 17q, 18q, and 21q. Thirteen monophasic and nine biphasic tumors had an average of 5.1 and 2.8 aberrations, respectively. Patients with tumors harboring numerous aberrations (≥3) had a worse clinical course. Microarray CGH more specifically detected genetic imbalances including gains in MDM2, MSH2, KCNK12, DCC, CDK2, ERBB3, SAS, and CDK4 and losses in HRAS, RASSF1, and CCND1. Gain of SAS was an important prognostic factor of SS. Conclusion: We have identified several factors influencing the prognosis of SS patients by metaphase and microarray CGH.