Association of SYT-SSX fusion types with proliferative activity and prognosis in synovial sarcoma

The t(X;18)(p11.2;q11.2) translocation commonly found in synovial sarcoma ( SS) results in the fusion of the SYT gene on chromosome 18 to either of two closely related genes, SSX1 and SSX2, on chromosome X It has been suggeste d that patients who have SS bearing SYT-SSX1 fusion have worse prognosis th an those bearing SYT-SSX2 fusion, However, Little is known about the biolog ic basis or the relationship with the histopathologic risk factors in regar d to the different fusion types. We analyzed 19 cases of SS with no metasta sis at diagnosis, These tumors were classified by reverse transcription-pol ymerase chain reaction to SYT-SSX1 and SYT-SSX2 types. The expression of Ki -67, p27, p53, and bcl-2 and various clinicopathologic parameters including mitotic rate were compared between the two fusion types. The SYT-SSX1 type fusion was associated with high Ki-67 expression (P = .011) and high mitot ic rate (P = .070). No significant differences were found between the two t ypes as to the expression of p27, p53, and bcl-2 and other clinicopathologi c parameters. The survival analysis showed that SYT-SSX1-type fusion, high Ki-67 expression, and high mitotic rate correlated with shorter metastasis- free survival These data suggested that SYT-SSX fusion type is associated w ith tumor cell proliferative activity and prognosis of patients who have SS .