Pax3-fkhr and pax7-fkhr fusion genes impact outcome of alveolar rhabdomyosarcoma in children.

Rhabdomyosarcoma is a highly malignant embryonic tumor of childhood. Two specific translocations t(2;13)(q35;q14) and t(1;13)(p36;q14) have been identified in about 75-80% of ARMS cells. The aim of this multicenter study was to analyze the relationships between the identified fusion transcripts and survival including some selected clinical parameters. The extent of disease was graded according to clinical staging system with following distribution: 3 children with stage I, 4 with stage II, 23 with stage III, and 18 with stage IV spread disease having distant metastases. PAX3-FKHR fusion genes were detected in 28 and PAX7-FKHR fusion genes in 7 tumor biopsy specimens. Children with PAX3-FKHR fusion gene had often distant metastases at presentation (p = 0.03). PAX3-FKHR positive patients with locoregional disease had significantly poorer outcome compared with the ones with PAX7-FKHR positive tumors (p = 0.04). Although analyzed groups were small, significant differences in survival and clinical characteristics between PAX3-FKHR and PAX7-FKHR positive tumors were stated indicating their role in carcinogenesis. In addition, fusion gene analysis is a helpful tool in differential diagnosis of poorly differentiated soft tissue tumors.