title: An Analysis of Tumor- and Surgery-Related Factors that Contribute to Inadvertent Positive Margins Following Soft Tissue Sarcoma Resection.
abstract: BACKGROUND
  The risk of local recurrence (LR) after soft tissue sarcoma (STS) resection is higher in the setting of inadvertent positive margins (IPMs). This study assessed whether both tumor- and surgery-related factors contribute to IPMs, and whether tumor- versus surgery-related IPMs differ in LR or overall survival (OS).
  
  
  METHODS
  Retrospective review of a tertiary center database identified patients with IPMs following STS resection between 1989 and 2014. Of 2234 resected STSs, 309 (13%) had positive margins; 89 (4%) were IPMs. Mean follow-up was 52 months, mean tumor size was 9.2 cm, and 55% were high grade. Cases were categorized as surgery-related (67, 75%) or tumor-related (22, 25%).
  
  
  RESULTS
  There was a significant difference in positive margin location, with the deep margin commonly involved in surgery-related IPMs (55% vs. 9%; p < 0.001). Tissue type also differed (p = 0.01), with surgery-related IPMs frequently in muscle (33%), while tumor-related IPMs favored subcutaneous tissues (41%). STSs with surgery-related IPMs were larger (p = 0.01). Histologic subtypes differed (p = 0.02), with myxofibrosarcoma and undifferentiated pleomorphic sarcoma/malignant fibrous histiocytoma predominating in tumor-related IPMs (82%). The cumulative probability of LR after IPMs, with death as a competing risk, was 28% (95% confidence interval [CI] 18-35) at 5 years and 37% (95% CI 24-45) at 10 years. Mortality was 28% (95% CI 18-38) at 5 years and 38% (26-50) at 10 years. There was no difference in LR (p = 0.91) or OS (p = 0.44) between surgery- and tumor-related IPMS.
  
  
  CONCLUSIONS
  IPMs after STS resection results in substantial LR risk. While demonstrating distinct surgery- and tumor-related contributions, there was no between-group difference in LR or OS. These results may aid in avoiding IPMs.
  
  
  METHODS
  Therapeutic Level III, retrospective comparative study.
authors.affiliation: Department of Orthopaedics and Rehabilitation, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, OP31, Portland, OR, 97239, USA. gundle@ohsu.edu.|Operative Care Division, Portland VA Health Care System, Portland, OR, USA. gundle@ohsu.edu.
authors.forename: Kenneth R
authors.initials: KR
authors.lastname: Gundle
authors.affiliation: University of Glasgow, Glasgow, UK.
authors.forename: Sanjay
authors.initials: S
authors.lastname: Gupta
authors.affiliation: Texas Tech University Health Sciences Center El Paso, El Paso, TX, USA.
authors.forename: Lisa
authors.initials: L
authors.lastname: Kafchinski
authors.affiliation: University Musculoskeletal Oncology Unit, Mount Sinai Hospital, Toronto, ON, Canada.
authors.forename: Anthony M
authors.initials: AM
authors.lastname: Griffin
authors.affiliation: Department of Pathology and Laboratory Medicine, Mount Sinai Hospital, Toronto, ON, Canada.
authors.forename: Rita A
authors.initials: RA
authors.lastname: Kandel
authors.affiliation: Department of Pathology and Laboratory Medicine, Mount Sinai Hospital, Toronto, ON, Canada.
authors.forename: Brendan C
authors.initials: BC
authors.lastname: Dickson
authors.affiliation: Princess Margaret Cancer Centre, Toronto, ON, Canada.|Department of Radiation Oncology, University of Toronto, Toronto, ON, Canada.
authors.forename: Peter W
authors.initials: PW
authors.lastname: Chung
authors.affiliation: Princess Margaret Cancer Centre, Toronto, ON, Canada.|Department of Radiation Oncology, University of Toronto, Toronto, ON, Canada.
authors.forename: Charles N
authors.initials: CN
authors.lastname: Catton
authors.affiliation: Princess Margaret Cancer Centre, Toronto, ON, Canada.|Department of Radiation Oncology, University of Toronto, Toronto, ON, Canada.
authors.forename: Brian
authors.initials: B
authors.lastname: O'Sullivan
authors.affiliation: University Musculoskeletal Oncology Unit, Mount Sinai Hospital, Toronto, ON, Canada.|Division of Orthopaedic Surgery, Department of Surgery, University of Toronto, Toronto, ON, Canada.
authors.forename: Peter C
authors.initials: PC
authors.lastname: Ferguson
authors.affiliation: University Musculoskeletal Oncology Unit, Mount Sinai Hospital, Toronto, ON, Canada.|Division of Orthopaedic Surgery, Department of Surgery, University of Toronto, Toronto, ON, Canada.
authors.forename: Jay S
authors.initials: JS
authors.lastname: Wunder
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000401:mortality* / Q000473:pathology* / Q000601:surgery; D011379:Prognosis; D012189:Retrospective Studies; D012307:Risk Factors; D012509:Sarcoma / Q000401:mortality* / Q000473:pathology* / Q000601:surgery; D015996:Survival Rate; D055815:Young Adult