title: Potential role of FDG PET imaging in predicting metastatic potential and assessment of therapeutic response to neoadjuvant chemotherapy in Ewing sarcoma family of tumors.
abstract: OBJECTIVE
  The aim of this study was to retrospectively correlate FDG uptake in primary Ewing sarcoma family of tumors (ESFT) with tumor behavior, and to evaluate whether FDG PET can be used to predict response to neoadjuvant chemotherapy (NACT) in this patient group.
  
  
  METHODS
  Out of the total 54 patients of recently diagnosed ESFT who underwent pretreatment FDG PET imaging, group I included patients without metastasis at presentation (n = 34) and group II included those with metastasis at presentation (n = 20). Fourteen of these patients had undergone FDG PET after 4 cycles of induction chemotherapy and surgical resection of primary tumor. In this subgroup of 14 patients, maximum standardized uptake value (SUVmax) of primary tumor was estimated before and after 4 cycles of induction chemotherapy and was correlated with the histopathological response in terms of necrosis in the tumor specimen.
  
  
  RESULTS
  Mean SUVmax in the primary tumor in group I patients was 6.84 and in group II patients, it was 11.31. The difference between mean SUVmax of these 2 groups was significant by Wilcoxon test analysis, with P < 0.01. In group II patients, SUVmax in metastasis with maximum FDG uptake was consistently lower as compared with that of primary tumor. In subgroup of 14 patients, Pearson correlation analysis showed that percentage change in SUVmax of primary tumor correlated well with percentage necrosis on histopathological examination (P < 0.01).
  
  
  CONCLUSIONS
  FDG uptake in primary ESFT reflected its metastatic potential and hence the aggressive behavior. The significant correlation between change in metabolic activity of the primary tumor and histopathological response after neoadjuvant chemotherapy suggests that FDG PET may be an ideal noninvasive method to assess tumor behavior and response to therapy in ESFT.
authors: Radiation Medicine Centre, BARC, Tata Memorial Hospital Annexe, Mumbai, India.
authors: Khushboo
authors: K
authors: Gupta
authors: Alok
authors: A
authors: Pawaskar
authors: Sandip
authors: S
authors: Basu
authors: Mysore G R
authors: MG
authors: Rajan
authors: Ramesh V
authors: RV
authors: Asopa
authors: Brijesh
authors: B
authors: Arora
authors: Narendra
authors: N
authors: Nair
authors: Shripad
authors: S
authors: Banavali
mesh_terms: D000293:Adolescent; D000328:Adult; D005260:Female; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics; D006801:Humans; D008297:Male; D020360:Neoadjuvant Therapy; D009362:Neoplasm Metastasis; D049268:Positron-Emission Tomography; D012512:Sarcoma, Ewing / Q000000981:diagnostic imaging* / Q000188:drug therapy* / Q000473:pathology; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D019788:Fluorodeoxyglucose F18