title: Histologic subtype and margin of resection predict pattern of recurrence and survival for retroperitoneal liposarcoma.
abstract: OBJECTIVE
  The aim of this study was to determine the pattern of recurrence and prognostic significance of histologic subtype in a large series of patients with primary retroperitoneal liposarcoma.
  
  
  BACKGROUND
  Classification of liposarcoma into subtypes, based on morphologic features and cytogenetic aberrations, is now widely accepted. Previous studies have shown that high histologic grade and incomplete gross resection are the most important prognostic factors for survival in patients with retroperitoneal sarcoma and suggest that patients with liposarcoma have a 3-fold higher risk of local recurrence compared with other histologies.
  
  
  METHODS
  A prospective database was used to identify 177 patients with primary retroperitoneal liposarcoma treated between July 1982 and June 2002. Histology at primary presentation was reviewed by a sarcoma pathologist and subtyped into 4 distinct groups according to strict criteria. The influence of clinicopathological factors on local recurrence, distant recurrence, and disease-specific survival was analyzed.
  
  
  RESULTS
  Of 177 patients with primary retroperitoneal liposarcoma operated on for curative intent, 99 (56%) presented with well-differentiated, 65 (37%) with dedifferentiated, 9 (5%) with myxoid, and 4 (2%) with round cell morphology. The tumor burden was determined by the sum of the maximum tumor diameters. The median tumor burden was 26 cm (5-139). Median follow-up time for 92 (52%) surviving patients was 37 (mean, 0.5-192) months. Multivariate analysis showed that dedifferentiated liposarcoma subtype was associated with a 6-fold increased risk of death compared with well-differentiated histology (P < 0.0001). In addition to histologic subtype, incomplete resection (P < 0.0001), contiguous organ resection (excluding nephrectomy; P = 0.05), and age (P = 0.03) were important independent prognostic factors for survival in retroperitoneal liposarcoma. Retroperitoneal dedifferentiated liposarcoma was associated with an 83% local recurrence rate and 30% distant recurrence rate at 3 years.
  
  
  CONCLUSIONS
  The histologic subtype and margin of resection are prognostic for survival in primary retroperitoneal liposarcoma. Dedifferentiated histologic subtype and the need for contiguous organ resection (excluding nephrectomy) was associated with an increase risk of local and distant recurrence. Nephrectomy may be needed to achieve complete resection, but has no measurable influence on disease specific survival.
mesh_terms: D016208:Databases, Factual; D018572:Disease-Free Survival; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008080:Liposarcoma / Q000453:epidemiology / Q000473:pathology* / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009364:Neoplasm Recurrence, Local / Q000453:epidemiology; D009392:Nephrectomy; D011379:Prognosis; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012186:Retroperitoneal Neoplasms / Q000453:epidemiology / Q000473:pathology* / Q000601:surgery*; D012187:Retroperitoneal Space; D018570:Risk Assessment; D016019:Survival Analysis; D013997:Time Factors