title: Positron emission tomography (PET) evaluation after initial chemotherapy and radiation therapy predicts local control in rhabdomyosarcoma.
abstract: OBJECTIVE
  18-fluorodeoxyglucose positron emission tomography (PET) is already an integral part of staging in rhabdomyosarcoma. We investigated whether primary-site treatment response characterized by serial PET imaging at specific time points can be correlated with local control.
  
  
  METHODS
  We retrospectively examined 94 patients with rhabdomyosarcoma who received initial chemotherapy 15 weeks (median) before radiotherapy and underwent baseline, preradiation, and postradiation PET. Baseline PET standardized uptake values (SUVmax) and the presence or absence of abnormal uptake (termed PET-positive or PET-negative) both before and after radiation were examined for the primary site. Local relapse-free survival (LRFS) was calculated according to baseline SUVmax, PET-positive status, and PET-negative status by the Kaplan-Meier method, and comparisons were tested with the log-rank test.
  
  
  RESULTS
  The median patient age was 11 years. With 3-year median follow-up, LRFS was improved among postradiation PET-negative vs PET-positive patients: 94% vs 75%, P=.02. By contrast, on baseline PET, LRFS was not significantly different for primary-site SUVmax≤7 vs >7 (median), although the findings suggested a trend toward improved LRFS: 96% for SUVmax≤7 vs 79% for SUVmax>7, P=.08. Preradiation PET also suggested a statistically insignificant trend toward improved LRFS for PET-negative (97%) vs PET-positive (81%) patients (P=.06).
  
  
  CONCLUSIONS
  Negative postradiation PET predicted improved LRFS. Notably, 77% of patients with persistent postradiation uptake did not experience local failure, suggesting that these patients could be closely followed up rather than immediately referred for intervention. Negative baseline and preradiation PET findings suggested statistically insignificant trends toward improved LRFS. Additional study may further understanding of relationships between PET findings at these time points and outcome in rhabdomyosarcoma.
authors.affiliation: Department of Radiation Oncology, Memorial Sloan-Kettering, New York, New York 10065, USA. dharmark@mskcc.org
authors.forename: Kavita V
authors.initials: KV
authors.lastname: Dharmarajan
authors.forename: Leonard H
authors.initials: LH
authors.lastname: Wexler
authors.forename: Somali
authors.initials: S
authors.lastname: Gavane
authors.forename: Josef J
authors.initials: JJ
authors.lastname: Fox
authors.forename: Heiko
authors.initials: H
authors.lastname: Schoder
authors.forename: Ashlyn K
authors.initials: AK
authors.lastname: Tom
authors.forename: Alison N
authors.initials: AN
authors.lastname: Price
authors.forename: Paul A
authors.initials: PA
authors.lastname: Meyers
authors.forename: Suzanne L
authors.initials: SL
authors.lastname: Wolden
mesh_terms: D000293:Adolescent; D000328:Adult; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use; D002648:Child; D002675:Child, Preschool; D003131:Combined Modality Therapy / Q000379:methods; D018572:Disease-Free Survival; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D007223:Infant; D008297:Male; D049268:Positron-Emission Tomography / Q000379:methods*; D012372:ROC Curve; D019275:Radiopharmaceuticals; D011879:Radiotherapy Dosage; D012189:Retrospective Studies; D012208:Rhabdomyosarcoma / Q000000981:diagnostic imaging* / Q000188:drug therapy* / Q000473:pathology / Q000532:radiotherapy*; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18