title: Optimal Percent Myxoid Component to Predict Outcome in High-Grade Myxofibrosarcoma and Undifferentiated Pleomorphic Sarcoma.
abstract: BACKGROUND
  Myxofibrosarcoma and undifferentiated pleomorphic sarcoma (UPS) are aggressive, genetically complex sarcomas. The minimum myxoid component used as a criterion for myxofibrosarcoma varies widely, so we determined the optimal myxoid component cutpoints for stratifying outcomes of UPS and myxofibrosarcoma. We also analyzed clinicopathologic factors associated with outcome.
  
  
  METHODS
  Review of a prospective, single-institution database identified 197 patients with primary, high-grade extremity/truncal myxofibrosarcoma or UPS resected during 1992-2013. Histology was reviewed and percent myxoid component determined for each tumor. Disease-specific survival (DSS) and distant recurrence-free survival (DRFS) were analyzed using the Kaplan-Meier method, log-rank test, and Cox regression.
  
  
  RESULTS
  Median follow-up for survivors was 6.4 years. In minimum p value analysis of myxoid component, the best cutpoint for both DSS and DRFS was 5% (adjusted p ≤ 0.001), followed by 70%. Therefore, sarcomas with <5% myxoid component (n = 69) were classified as UPS and those with ≥5% myxoid component (n = 128) as myxofibrosarcoma. Five-year DRFS was 24% for UPS, 51% for 5-69% myxoid component myxofibrosarcoma, and 65% for ≥70% myxoid component myxofibrosarcoma. Myxoid component, tumor size, and age were independently associated with DSS; myxoid component and tumor size were associated with DRFS. Only tumor site was associated with local recurrence.
  
  
  CONCLUSIONS
  Percent myxoid component and tumor size are the two most important predictors of DSS and DRFS in high-grade myxofibrosarcoma and UPS. A 5% myxoid component cutpoint is an improved criterion for classifying myxofibrosarcoma. Myxoid component-based classification improves stratification of patient outcome and will aid in selection of patients for systemic therapy and clinical trials.
authors.affiliation: Sarcoma Biology Laboratory, Sarcoma Disease Management Program, Department of Surgery, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
authors.forename: Ann Y
authors.initials: AY
authors.lastname: Lee
authors.affiliation: Department of Pathology, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
authors.forename: Narasimhan P
authors.initials: NP
authors.lastname: Agaram
authors.affiliation: Department of Biostatistics, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
authors.forename: Li-Xuan
authors.initials: LX
authors.lastname: Qin
authors.affiliation: Department of Biostatistics, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
authors.forename: Deborah
authors.initials: D
authors.lastname: Kuk
authors.affiliation: Sarcoma Biology Laboratory, Sarcoma Disease Management Program, Department of Surgery, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
authors.forename: Christina
authors.initials: C
authors.lastname: Curtin
authors.affiliation: Sarcoma Biology Laboratory, Sarcoma Disease Management Program, Department of Surgery, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
authors.forename: Murray F
authors.initials: MF
authors.lastname: Brennan
authors.affiliation: Sarcoma Biology Laboratory, Sarcoma Disease Management Program, Department of Surgery, Memorial Sloan Kettering Cancer Center, New York, NY, USA. singers@mskcc.org.
authors.forename: Samuel
authors.initials: S
authors.lastname: Singer
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005350:Fibroma / Q000145:classification / Q000473:pathology* / Q000601:surgery; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading; D011379:Prognosis; D011446:Prospective Studies; D012509:Sarcoma / Q000145:classification / Q000473:pathology* / Q000601:surgery; D015996:Survival Rate; D055815:Young Adult