title: Variability in Patterns of Recurrence After Resection of Primary Retroperitoneal Sarcoma (RPS): A Report on 1007 Patients From the Multi-institutional Collaborative RPS Working Group.
abstract: BACKGROUND
  Retroperitoneal sarcomas (RPS) are rare tumors composed of several well defined histologic subtypes. The aim of this study was to analyze patterns of recurrence and treatment variations in a large population of patients, treated at reference centers.
  
  
  METHODS
  All consecutive patients with primary RPS treated at 6 European and 2 North American institutions between January 2002 and December 2011 were included. Five, 8, and 10-year overall survival (OS) and crude cumulative incidence (CCI) of local recurrence (LR) and distant metastasis (DM) were calculated. Multivariate analyses for OS, CCI of LR, and DM were performed.
  
  
  RESULTS
  In all, 1007 patients were included. Median follow-up was 58 months (first and third quartile range 36-90). The 5, 8, and 10-year OS were 67% [95% confidence interval (CI), 63, 70), 56% (95% CI, 52, 61), and 46% (95% CI, 40, 53). The 5, 8, and 10-year CCI of LR and DM were 25.9 (95% CI, 23.1, 29.1), 31.3 (95% CI, 27.8, 35.1), 35% (95% CI, 30.5, 40.1), and 21% (95% CI, 18.4, 23.8%), 21.6 (95% CI, 19.0, 24.6), and 21.6 (95% CI, 19.0, 24.6), respectively. Tumour size, histologic subtype, malignancy grade, multifocality, and completeness of resection were significant predictors of outcome. Patterns of recurrence varied depending on histologic subtype. Different treatment policies at participating institutions influenced LR of well differentiated liposarcoma without impacting OS, whereas discrepancies in adjuvant systemic therapies did not impact LR, DM, or OS of leiomyosarcoma.
  
  
  CONCLUSIONS
  Reference centers are critical to outcomes of RPS patients, as the management strategy requires specific expertise. Histologic subtype predicts patterns of recurrence and should inform management decision. A prospective international registry is under preparation, to further define our understanding of this disease.
authors.affiliation: *Department of Surgery, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy †Department of Surgery, Royal Marsden Hospital NHS Foundation Trust, London, United Kingdom ‡Department of Biostatistics, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy §Department of Surgery, Institute Gustave Roussy, Villejuif, France ¶Department of Surgical Oncology, Mount Sinai Hospital and Princess Margaret Cancer Centre, and Department of Surgery, University of Toronto, Toronto, Ontario, Canada ||Division of Surgical Oncology & Thoracic Surgery, Mannheim University Hospital, Mannheim, Germany **Department of Surgical Oncology, Netherlands Cancer Institute, Amsterdam, The Netherlands ††Department of Soft Tissue/Bone Sarcoma and Melanoma, Maria Sklodowska-Curie Memorial Cancer Center and Institute of Oncology, Warsaw, Poland ‡‡Department of Surgery, Division of Surgical Oncology, Brigham and Women's Hospital and Center for Sarcoma and Bone Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA §§Department of Radiation Oncology, Netherlands Cancer Institute, Amsterdam, The Netherlands ¶¶Department of Cancer Medicine, Fondazione IRCCS Istituto Nazionale dei Tumori, Milan, Italy ||||Department of Surgery, Division of Surgical Oncology, Ohio State University Medical Center, Columbus, OH.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Gronchi
authors.forename: Dirk C
authors.initials: DC
authors.lastname: Strauss
authors.forename: Rosalba
authors.initials: R
authors.lastname: Miceli
authors.forename: Sylvie
authors.initials: S
authors.lastname: Bonvalot
authors.forename: Carol J
authors.initials: CJ
authors.lastname: Swallow
authors.forename: Peter
authors.initials: P
authors.lastname: Hohenberger
authors.forename: Frits
authors.initials: F
authors.lastname: Van Coevorden
authors.forename: Piotr
authors.initials: P
authors.lastname: Rutkowski
authors.forename: Dario
authors.initials: D
authors.lastname: Callegaro
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Hayes
authors.forename: Charles
authors.initials: C
authors.lastname: Honoré
authors.forename: Mark
authors.initials: M
authors.lastname: Fairweather
authors.forename: Amanda
authors.initials: A
authors.lastname: Cannell
authors.forename: Jens
authors.initials: J
authors.lastname: Jakob
authors.forename: Rick L
authors.initials: RL
authors.lastname: Haas
authors.forename: Milena
authors.initials: M
authors.lastname: Szacht
authors.forename: Marco
authors.initials: M
authors.lastname: Fiore
authors.forename: Paolo G
authors.initials: PG
authors.lastname: Casali
authors.forename: Raphael E
authors.initials: RE
authors.lastname: Pollock
authors.forename: Chandrajit P
authors.initials: CP
authors.lastname: Raut
mesh_terms: D000368:Aged; D005060:Europe / Q000453:epidemiology; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D060787:Neoplasm Grading; D009362:Neoplasm Metastasis; D009364:Neoplasm Recurrence, Local / Q000453:epidemiology*; D009656:North America / Q000453:epidemiology; D011446:Prospective Studies; D012186:Retroperitoneal Neoplasms / Q000401:mortality / Q000473:pathology* / Q000601:surgery*; D012307:Risk Factors; D012509:Sarcoma / Q000401:mortality / Q000473:pathology* / Q000601:surgery*; D015996:Survival Rate