title: Correlation between fluid-fluid levels on initial MRI and the response to chemotherapy in stage IIb osteosarcoma.
abstract: BACKGROUND
  The presence of fluid-fluid levels (FFLs) on osteosarcoma magnetic resonance imaging (MRI) is underestimated as a nonspecific finding; however, we hypothesized that FFL in conventional osteosarcoma may be indicative of chemoresistance.
  
  
  METHODS
  In 567 stage IIB osteosarcoma patients, we evaluated the following: the incidence of FFL and their correlation with other clinicopathological variables; tumor volume change after chemotherapy and survival according to the presence of FFL; and the relationship between survival and the extent of FFL.
  
  
  RESULTS
  One hundred eight (19 %) tumors showed FFL on initial MRI. FFL were correlated with proximal humeral location (P = 0.017), osteolytic on plain radiographs (P < 0.001), tumor enlargement after chemotherapy (P < 0.001), and poor histological response (P = 0.005). Large tumor (P < 0.01), proximal tumor location (P = 0.01), and presence of FFL (P < 0.01) were independent predictors of poor survival. Compared to the extensive FFL (more than one third of the tumor), small foci of FFL (less than one third of the tumor) showed a high tendency for tumor enlargement after chemotherapy (P < 0.001), poor histologic response (P = 0.001), and worse survival (P < 0.001).
  
  
  CONCLUSIONS
  FFL on initial MRI could predict tumor progression after chemotherapy. Notably, tumors with small foci of FFL (less than one third of the tumor) have a high propensity for poor outcome. Patients with this finding should be considered for risk-adapted therapy.
authors.affiliation: Department of Orthopedic Surgery, Korea Cancer Center Hospital, Seoul, Korea, dgjeon@kcch.re.kr.
authors.forename: Dae-Geun
authors.initials: DG
authors.lastname: Jeon
authors.forename: Wan Hyeong
authors.initials: WH
authors.lastname: Cho
authors.forename: Won Seok
authors.initials: WS
authors.lastname: Song
authors.forename: Chang-Bae
authors.initials: CB
authors.lastname: Kong
authors.forename: Sang Hyun
authors.initials: SH
authors.lastname: Cho
authors.forename: Jung Wook
authors.initials: JW
authors.lastname: Lee
authors.forename: Soo-Yong
authors.initials: SY
authors.lastname: Lee
mesh_terms: D000293:Adolescent; D000328:Adult; D000970:Antineoplastic Agents / Q000627:therapeutic use; D001826:Body Fluids; D001859:Bone Neoplasms / Q000188:drug therapy* / Q000473:pathology* / Q000601:surgery; D017024:Chemotherapy, Adjuvant; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D020360:Neoadjuvant Therapy; D009367:Neoplasm Staging; D012516:Osteosarcoma / Q000188:drug therapy* / Q000473:pathology* / Q000601:surgery; D011379:Prognosis; D012189:Retrospective Studies; D015996:Survival Rate; D047368:Tumor Burden; D055815:Young Adult
chemical_list: D000970:Antineoplastic Agents