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Ultra-Rare Sarcomas: A Consensus Paper From the Connective Tissue Oncology Society Community of Experts on the Incidence Threshold and the List of Entities

  • Stacchiotti, Silvia1
  • Frezza, Anna Maria1
  • Blay, Jean-Yves2
  • Baldini, Elizabeth H.3
  • Bonvalot, Sylvie4
  • Bovée, Judith V. M. G.5
  • Callegaro, Dario6
  • Casali, Paolo G.1
  • Chiang, RuRu Chun-ju7, 8
  • Demetri, George D.9
  • Demicco, Elisabeth G.10
  • Desai, Jayesh11
  • Eriksson, Mikael12
  • Gelderblom, Hans13
  • George, Suzanne9
  • Gounder, Mrinal M.14, 15
  • Gronchi, Alessandro6
  • Gupta, Abha16, 17
  • Haas, Rick L.18, 19
  • Hayes-Jardon, Andrea20
  • And 37 more
  • 1 Department of Medical Oncology, National Cancer Institute of Milan, Milan, Italy
  • 2 Leon Berard Center, Claude Bernard University Lyon 1, UNICANCER Hospital Network, Lyon, France
  • 3 Department of Radiation Oncology, Dana-Farber/Brigham and Women’s Cancer Center, Boston, Massachusetts
  • 4 Department of Surgical Oncology, Curie Institute, University of Paris-Sciences and Letters, Paris, France
  • 5 Department of Pathology, Leiden University Medical Center, Leiden, Netherlands
  • 6 Department of Surgery, National Cancer Institute of Milan, Milan, Italy
  • 7 Taiwan Cancer Registry Center, Taipei, Taiwan
  • 8 Institute of Epidemiology and Preventive Medicine, College of Public Health, National Taiwan University, Taipei, Taiwan
  • 9 Department of Medical Oncology, Ludwig Center at Harvard Medical School, Dana-Farber Cancer Institute, Boston, Massachusetts
  • 10 Department of Pathobiology and Laboratory Medicine, University of Toronto/Mount Sinai Hospital, Toronto, Ontario, Canada
  • 11 Department of Medical Oncology, Peter MacCallum Cancer Center, Melbourne, Victoria, Australia
  • 12 Department of Oncology, Skane University Hospital and Lund University, Lund, Sweden
  • 13 Department of Medical Oncology, Leiden University Medical Center, Leiden, Netherlands
  • 14 Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, New York
  • 15 Weill Cornell Medical College, New York, New York
  • 16 Division of Hematology/Oncology, The Hospital for Sick Children, Toronto, Ontario, Canada
  • 17 Princess Margaret Cancer Center, Toronto, Ontario, Canada
  • 18 Department of Radiotherapy, Netherlands Cancer Institute, Amsterdam, Netherlands
  • 19 Department of Radiotherapy, Leiden University Medical Center, Amsterdam, Netherlands
  • 20 Department of Surgery, the Royal Marsden National Health Service Foundation Trust, London, United Kingdom
  • 21 Sarcoma Unit, Mannheim University Medical Center, University of Heidelberg, Mannheim, Germany
  • 22 Department of Orthopedics, University of Utah, Salt Lake City, Utah
  • 23 Sarcoma Unit, Royal Marsden NHS Foundation Trust/Institute of Cancer Research, London, UK
  • 24 Department of Musculoskeletal Oncology, National Cancer Center Hospital, Tokyo, Japan
  • 25 Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina
  • 26 s
  • 27 Medical Oncology, Gustave Roussy Institute, Villejuif, Ile-de-France, France
  • 28 Division of Cancer Registration and Surveillance, National Cancer Center, Ilsandong-gu, Goyang-si, Republic of Korea
  • 29 Department of Epidemiology, Regional Health Council, Biomedical Research Institute of Murcia-Arrixaca, Murcia University, Murcia, Spain
  • 30 Unit of Oncogenetics and Functional Oncogenomics, Aviano IRCCS Oncology Referral Center, Aviano, Italy
  • 31 Epidemiology Unit and Girona Cancer Registry, Oncology Coordination Plan, Department of Health, Autonomous Government of Catalonia, Catalan Institute of Oncology, Girona, Spain
  • 32 Medical Oncology Department, University Hospital Virgen del Rocio, Sevilla, Spain
  • 33 National Cancer Registry Section, Center for Cancer Registries, Center for Cancer Control and Information Services, National Cancer Center, Tokyo, Japan
  • 34 Department of Sarcoma Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas
  • 35 Department of Surgery, Brigham and Women’s Hospital, Boston, Massachusetts
  • 36 Center for Sarcoma and Bone Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, Massachusetts
  • 37 Department of Interdisciplinary Cancer Management, Moffitt Cancer Center, Tampa, Florida
  • 38 Department of Soft Tissue/Bone Sarcoma and Melanoma, Maria Sklodowska-Curie National Research Institute of Oncology, Warsaw, Poland
  • 39 Department of Pathology, University Hospital of Padova, Padova, Italy
  • 40 Department of Pathology, Brigham and Women’s Hospital, Harvard Medical School, Boston, Massachusetts
  • 41 Department of Oncology, the Norwegian Radium Hospital, Oslo University Hospital, Oslo, Norway
  • 42 Garvan Institute of Medical Research, Sydney, New South Wales, Australia
  • 43 Department of Medical Oncology, Netherlands Cancer Institute Amsterdam, Amsterdam, Netherlands
  • 44 Department of Surgical Oncology, Netherlands Cancer Institute, Amsterdam, Netherlands
  • 45 Department of Registration, Netherlands Comprehensive Cancer Organization, Utrecht, Netherlands
  • 46 Department of Hematology and Medical Oncology, Fox Chase Cancer Center, Philadelphia, Pennsylvania
  • 47 Department of Medicine, University of Colorado Cancer Center, Aurora, Colorado
  • 48 Evaluative Epidemiology Unit, Department of Research, National Cancer Institute of Milan, Milan, Italy
Published Article
Wiley (John Wiley & Sons)
Publication Date
Apr 28, 2021
DOI: 10.1002/cncr.33618
PMID: 33910263
PMCID: PMC8319065
PubMed Central
  • Article


BACKGROUND: Among sarcomas, which are rare cancers, many types are exceedingly rare; however, a definition of ultra-rare cancers has not been established. The problem of ultra-rare sarcomas is particularly relevant because they represent unique diseases, and their rarity poses major challenges for diagnosis, understanding disease biology, generating clinical evidence to support new drug development, and achieving formal authorization for novel therapies. METHODS: The Connective Tissue Oncology Society promoted a consensus effort in November 2019 to establish how to define ultra-rare sarcomas through expert consensus and epidemiologic data and to work out a comprehensive list of these diseases. The list of ultra-rare sarcomas was based on the 2020 World Health Organization classification, The incidence rates were estimated using the Information Network on Rare Cancers (RARECARENet) database and NETSARC (the French Sarcoma Network’s clinical-pathologic registry). Incidence rates were further validated in collaboration with the Asian cancer registries of Japan, Korea, and Taiwan. RESULTS: It was agreed that the best criterion for a definition of ultra-rare sarcomas would be incidence. Ultra-rare sarcomas were defined as those with an incidence of approximately ≤1 per 1,000,000, to include those entities whose rarity renders them extremely difficult to conduct well powered, prospective clinical studies. On the basis of this threshold, a list of ultra-rare sarcomas was defined, which comprised 56 soft tissue sarcoma types and 21 bone sarcoma types. CONCLUSIONS: Altogether, the incidence of ultra-rare sarcomas accounts for roughly 20% of all soft tissue and bone sarcomas. This confirms that the challenges inherent in ultra-rare sarcomas affect large numbers of patients.

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