title: Use of reverse transcriptase polymerase chain reaction for diagnosis and staging of alveolar rhabdomyosarcoma, Ewing sarcoma family of tumors, and desmoplastic small round cell tumor.
abstract: OBJECTIVE
  To compare the use of reverse transcriptase polymerase chain reaction (RT-PCR) with that of morphology-based methods for diagnosis, staging, and detection of metastatic disease in pediatric alveolar rhabdomyosarcoma (ARMS), Ewing sarcoma family of tumors (ESFT), and desmoplastic small round cell tumors (DSRCT).
  
  
  METHODS
  RT-PCR assays for the EWS-FLII, EWS-ERG, PAX3-FKHR, PAX7-FKHR, and EWS-WTI fusion transcripts were performed on RNA extracted from the primary tumor tissue, bone marrow, and body fluids obtained at initial presentation and relapse. Molecular findings were compared with original histologic diagnoses and results of staging procedures.
  
  
  RESULTS
  Eighty-eight samples from 47 patients with ARMS (n = 13), ESFT (n = 31), or DSRCT (n = 3) were analyzed. The detection rate of metastatic disease was significantly higher with RT-PCR (95%) as compared with the morphologic methods (70%) for the three pediatric sarcomas studied. In primary tumors with characteristic fusion transcript, RT-PCR was positive in all cases with morphologic evidence of metastatic disease. Moreover, in six patients (3 with ARMS, 2 with DSRCT, and 1 with ESFT) with metastatic disease, micrometastases in bone marrow (4) and other sites (2) were detected by RT-PCR alone. Importantly, none of the patients with localized disease diagnosed had micrometastases detected by RT-PCR in bone marrow.
  
  
  CONCLUSIONS
  The high sensitivity and specificity of RT-PCR for the characteristic fusion transcripts of pediatric sarcomas make it an ideal method to aid in the routine staging of these patients. In addition, the 100% sensitivity of RT-PCR in detection of micrometastasis makes it useful for follow-up and detection of minimal residual disease. However, the clinical significance of molecularly-detectable disease remains unknown. Further studies should aim to elucidate the therapeutic and prognostic implications of micrometastases detected by RT-PCR alone.
authors.affiliation: Department of Hematology-Oncology, St Jude Children's Research Hospital, Memphis, Tennessee 38105-2794, USA.
authors.forename: U H
authors.initials: UH
authors.lastname: Athale
authors.forename: S A
authors.initials: SA
authors.lastname: Shurtleff
authors.forename: J J
authors.initials: JJ
authors.lastname: Jenkins
authors.forename: C A
authors.initials: CA
authors.lastname: Poquette
authors.forename: M
authors.initials: M
authors.lastname: Tan
authors.forename: J R
authors.initials: JR
authors.lastname: Downing
authors.forename: A S
authors.initials: AS
authors.lastname: Pappo
mesh_terms: D014408:Biomarkers, Tumor / Q000235:genetics*; D001853:Bone Marrow / Q000473:pathology; D001859:Bone Neoplasms / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology; D002648:Child; D002877:Chromosomes, Human / Q000235:genetics; D003937:Diagnosis, Differential; D006801:Humans; D009362:Neoplasm Metastasis; D009367:Neoplasm Staging; D018365:Neoplasm, Residual; D015514:Oncogene Proteins, Fusion / Q000235:genetics*; D051789:Proto-Oncogene Protein c-fli-1; D012333:RNA, Messenger / Q000235:genetics*; D012334:RNA, Neoplasm / Q000235:genetics*; D034802:RNA-Binding Protein EWS; D020133:Reverse Transcriptase Polymerase Chain Reaction; D018232:Rhabdomyosarcoma, Alveolar / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology; D012512:Sarcoma, Ewing / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology; D018228:Sarcoma, Small Cell / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology; D012680:Sensitivity and Specificity; D012983:Soft Tissue Neoplasms / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology; D014157:Transcription Factors / Q000235:genetics; D014178:Translocation, Genetic
chemical_list: D014408:Biomarkers, Tumor; C106031:EWS-FLI fusion protein; C106032:EWS1-WT1 fusion protein, human; D015514:Oncogene Proteins, Fusion; D051789:Proto-Oncogene Protein c-fli-1; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D034802:RNA-Binding Protein EWS; D014157:Transcription Factors