Clinical impact of molecular and cytogenetic findings in synovial sarcoma.
Synovial sarcoma is an aggressive soft-tissue tumor that accounts for up to 10% of soft-tissue sarcomas. Cytogenetically, synovial sarcoma is characterized by the t(X;18)(p11;q11), found in more than 95% of the tumors. This translocation results in rearrangements of the SYT gene in 18q11 and one of the SSX1, SSX2, or SSX4 genes in Xp11, creating a SYT/SSX1, SYT/SSX2, or SYT/SSX4 chimeric gene. It has been shown that patients with SYT/SSX1 fusion genes have a shorter metastasis-free survival than do patients with SYT/SSX2. Previous studies have also suggested that clonal evolution may be associated with disease progression. In the present study, RT-PCR analysis showed that all 64 examined synovial sarcomas from 54 patients had SYT-SSX chimeric genes. SYT/SSX1 was found in 40 tumors from 33 patients, SYT/SSX2 in 23 tumors from 20 patients, and SYT/SSX4 in one case. Two patients had variant SYT/SSX2 transcripts, with 57 bp and 141 bp inserts, respectively, between the known SYT and SSX2 sequences. Patients with tumors with SYT/SSX1 fusions had a higher risk of developing metastases compared to those with SYT/SSX2 fusions (P = 0.01). The reciprocal transcripts SSX1/SYT and SSX2/SYT were detected using nested PCR in 11 of the 40 samples with SYT/SSX1 and 5 of the 23 samples with SYT/SSX2, respectively. Among 20 blood samples, SYT/SSX1 and SYT/SSX2 were detected in one sample each. The t(X;18), or variants thereof, was found cytogenetically in all patients but three. Among 32 primary tumors, the t(X;18) or a variant translocation was the sole anomaly in 10. In contrast, of the seven metastatic lesions that were investigated prior to radiotherapy, only one had a t(X;18) as the sole anomaly; all other tumors displayed complex karyotypes. Cytogenetic complexity in primary tumors was, however, not associated with the development of metastases. Tumors with SYT/SSX2 less often (4/12 vs. 7/15) showed complex karyotypes than did tumors with SYT/SSX1, but the difference was not significant. Combining cytogenetic complexity and transcript data, we found that the subgroup of patients with tumors showing simple karyotypes and SYT/SSX2 fusion had the best clinical outcome (2/8 patients developed metastases), and those with tumors showing complex karyotypes together with SYT/SSX1 fusion the worst (6/7 patients developed metastases). This corresponded to 5-year metastasis-free survival rates of 0.58 and 0.0, respectively (P = 0.02).
Panagopoulos
I
I
Department of Clinical Genetics, Lund University Hospital, SE-221 85 Lund, Sweden. Ioannis.Panagopoulos@klingen.lu.se
Mertens
F
F
Isaksson
M
M
Limon
J
J
Gustafson
P
P
Skytting
B
B
Akerman
M
M
Sciot
R
R
Dal Cin
P
P
Samson
I
I
Iliszko
M
M
Ryoe
J
J
Dêbiec-Rychter
M
M
Szadowska
A
A
Brosjö
O
O
Larsson
O
O
Rydholm
A
A
Mandahl
N
N
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000595:Amino Acid Sequence; D001483:Base Sequence; D002648:Child; D005260:Female; D006801:Humans; D007621:Karyotyping; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins / Q000235:genetics; D015514:Oncogene Proteins, Fusion / Q000235:genetics; D011506:Proteins / Q000235:genetics; D011518:Proto-Oncogene Proteins; D012097:Repressor Proteins / Q000235:genetics; D013584:Sarcoma, Synovial / Q000175:diagnosis / Q000235:genetics*; D017422:Sequence Analysis, DNA; D012983:Soft Tissue Neoplasms / Q000175:diagnosis / Q000235:genetics*
D009363:Neoplasm Proteins; D015514:Oncogene Proteins, Fusion; D011506:Proteins; D011518:Proto-Oncogene Proteins; D012097:Repressor Proteins; C093961:SS18 protein, human; C093962:synovial sarcoma X breakpoint proteins