Research Article High-Grade Osteosarcoma of the Foot: Presentation, Treatment, Prognostic Factors, and Outcome of 23 Cooperative Osteosarcoma Study Group COSS Patients Anne J. Schuster , 1 Leo Kager, 2 Peter Reichardt, 3 Daniel Baumhoer, 4 MonikaCs´ oka, 5 Stefanie Hecker-Nolting, 1 Susanna Lang, 6 Sylvie Lorenzen, 7 Regine Mayer-Steinacker, 8 Thekla von Kalle, 9 Matthias Kevric, 1 Mathias Werner, 3 Reinhard Windhager , 10 Thomas Wirth, 11 and Stefan S. Bielack 1,12 1 Center for Pediatric, Adolescent and Women’s Medicine, Olgahospital, Department of Pediatrics 5 (Oncology, Hematology, Immunology), Klinikum Stuttgart, Stuttgart, Germany 2 St. Anna Children’s Hospital, Department of Paediatrics, Medical University of Vienna and Children’s Cancer Research Institute (CCRI), Vienna, Austria 3 Department of Interdisciplinary Oncology, HELIOS Klinikum Berlin-Buch, Berlin, Germany 4 Bone Tumour Reference Centre (BTRC), Institute of Pathology, University Hospital of Basel and University of Basel, Basel, Switzerland 5 2nd Department of Pediatrics, Semmelweis University, Budapest, Hungary 6 Department of Pathology, Vienna General Hospital, Medical University of Vienna, Vienna, Austria 7 Department of Hematology and Oncology, Klinikum rechts der Isar Technische Universit¨ at M¨ unchen, Munich, Germany 8 Department of Internal Medicine III, University of Ulm, Ulm, Germany 9 Center for Pediatric, Adolescent and Women’s Medicine, Olgahospital, Department of Pediatric Radiology, Klinikum Stuttgart, Stuttgart, Germany 10 Department of Orthopaedics, Medical University of Vienna, Vienna, Austria 11 Center for Pediatric, Adolescent and Women’s Medicine, Olgahospital, Department of Pediatrics, Division of Pediatric Orthopedics, Klinikum Stuttgart, Stuttgart, Germany 12 Department of Pediatric Hematology and Oncology, University Children’s Hospital Muenster, Muenster, Germany Correspondence should be addressed to Anne J. Schuster; anne.schuster@klinikum-stuttgart.de Received 21 November 2017; Revised 15 February 2018; Accepted 18 March 2018; Published 2 May 2018 Academic Editor: Valerae O. Lewis Copyright © 2018 Anne J. Schuster et al. is is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Osteosarcoma of the foot is a very rare presentation of a rare tumor entity. In a retrospective analysis, we investigated tumor- and treatment-related variables and outcome of patients registered in the Cooperative Osteosarcoma Study Group (COSS) database between January 1980 and April 2016 who suffered from primary high-grade osteosarcoma of the foot. Among the 23 eligible patients, median age was 32 years (range: 6–58 years), 10 were female, and 13 were male. e tarsus was the most commonly affected site (n � 16). ree patients had primary metastases. All patients were operated: 5 underwent primary surgery and 18 received surgery following preoperative chemotherapy. In 21 of the 23 patients, complete surgical remission was achieved. In 4 of 17 patients, a poor response to neoadjuvant chemotherapy was observed in the resected primary tumors. Median follow-up was 4.2 years (range: 0.4–18.5). At the last follow-up, 15 of the 23 patients were alive and 8 had died. Five-year overall and event-free survival estimates were 64% (standard error (SE) 12%) and 54% (SE 13%), which is similar to that observed for osteosarcoma in general. Event-free and overall survival correlated with primary metastatic status and completeness of surgery. Our findings show that high-grade osteosarcoma in the foot has a similar outcome as osteosarcoma of other sites. Hindawi Sarcoma Volume 2018, Article ID 1632978, 11 pages https://doi.org/10.1155/2018/1632978