title: Resectable well-differentiated versus dedifferentiated liposarcomas: two different diseases possibly requiring different treatment approaches.
abstract: BACKGROUND
  Division of retroperitoneal liposarcoma (RPLS) into well-differentiated (WD) and dedifferentiated (DD) subtypes is established; however, WD and DD are usually treated similarly. We hypothesized that WD and DD have distinct biological behaviors mandating different treatments.
  
  
  METHODS
  A prospective sarcoma database identified all primary/recurrent RPLS treated between 1996 and 2007: 77 DD (52%) and 58 WD (39.2%) patients were analyzed for recurrence rate, recurrence free survival (RFS), and overall survival (OS).
  
  
  RESULTS
  At presentation, WD were mostly primary whereas DD were mostly recurrent (75.9% versus 58.4%; p = 0.04). A significant proportion of DD (37.7%) received chemotherapy compared to WD (1.7%; p < 0.0001). Multivisceral resection was more common in DD versus WD (45.5% versus 31%; p = 0.01). Gross total resection rates were equivalent (WD: 86.2%; DD: 85.7%). Overall and local recurrence were higher in DD versus WD (82.2% versus 50% and 71.2% versus 46.3%; p < 0.0001). Only 3.7% WD recurred as high grade metastatic disease. Median time to recurrence was 55.5 months in WD versus 13.5 months in DD (p < 0.0001). RFS and OS (1, 2, and 5 year) were higher in WD than DD (80.3% versus 55.9%; 65.1% versus 34.1%; 41.9% versus 7.8%; p < 0.0001) and (98% versus 88.1%; 95.6% versus 71.9%; 92.1% versus 36.5%; p < 0.0001) respectively.
  
  
  CONCLUSIONS
  WD and DD have distinct biological behaviors. Gross total resection is achievable in most WD; unlike DD, high-grade recurrence is uncommon. Treatment should therefore reflect these biologic differences by maximizing survivorship while avoiding unnecessarily extensive multivisceral resection.
  
  
  CONCLUSIONS
  The biological behaviors of well-differentiated and dedifferentiated liposarcomas differ significantly. This article presents outcomes of two different surgical approaches that were implemented at the UTMDACC, treating these tumors as different disease entities.
authors.affiliation: Department of Surgical Oncology, The University of Texas MD Anderson Cancer Center, 1515 Holcombe Blvd, Unit 0444, Houston, Texas, USA.
authors.forename: G
authors.initials: G
authors.lastname: Lahat
authors.forename: D A
authors.initials: DA
authors.lastname: Anaya
authors.forename: X
authors.initials: X
authors.lastname: Wang
authors.forename: D
authors.initials: D
authors.lastname: Tuvin
authors.forename: D
authors.initials: D
authors.lastname: Lev
authors.forename: R E
authors.initials: RE
authors.lastname: Pollock
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019992:Databases as Topic; D005260:Female; D006801:Humans; D008080:Liposarcoma / Q000401:mortality / Q000473:pathology* / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D012186:Retroperitoneal Neoplasms / Q000401:mortality / Q000473:pathology* / Q000601:surgery*; D016019:Survival Analysis