ORIGINAL ARTICLE – BONE AND SOFT TISSUE SARCOMAS Osteosarcoma in Asian Populations Over the Age of 40 Years: A Multicenter Study Min Wook Joo, MD 1 , Seung Han Shin, MD, PhD 2 , Yong-Koo Kang, MD, PhD 1 , Akira Kawai, MD, PhD 3 , Han Soo Kim, MD, PhD 4 , Apichat Asavamongkolkul, MD 5 , Dae-Geun Jeon, MD, PhD 6 , Jae Do Kim, MD, PhD 7 , Xiaohui Niu, MD, PhD 8 , Hiroyuki Tsuchiya, MD, PhD 9 , Ajay Puri, MS 10 , Edward H. M. Wang, MD, PhD 11 , So Hak Chung, MD, PhD 7 , and Yang-Guk Chung, MD, PhD 2 1 Department of Orthopaedic Surgery, St. Vincent’s Hospital, College of Medicine, The Catholic University of Korea, Suwon-si, Gyeonggi-do, Republic of Korea; 2 Department of Orthopaedic Surgery, Seoul St. Mary’s Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea; 3 Department of Musculoskeletal Oncology, National Cancer Center Hospital, Tokyo, Japan; 4 Department of Orthopaedic Surgery, Seoul National University Hospital, Seoul, Republic of Korea; 5 Department of Orthopaedic Surgery, Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok, Thailand; 6 Department of Orthopedic Surgery, Korea Cancer Center Hospital, Seoul, Korea; 7 Department of Orthopaedic Surgery, Kosin University Gospel Hospital, Busan, Korea; 8 Department of Orthopedic Oncology Surgery, Beijing Ji Shui Tan Hospital, Beijing, China; 9 Department of Orthopaedic Surgery, School of Medicine, Kanazawa University, Kanazawa, Japan; 10 Department of Orthopaedic Oncology, Tata Memorial Hospital, Mumbai, India; 11 Tumor Service, Department of Orthopedics, College of Medicine and Philippine General Hospital, University of the Philippines Manila, Manila, Philippines ABSTRACT Background. Elderly patients with osteosarcoma (OSA) are no longer uncommon; however, many questions remain regarding this population. We investigated the clinico- pathological characteristics and prognostic factors of OSA in an Asian population over the age of 40 years. Methods. This was a multi-national, multi-institutional study by the Eastern Asian Musculoskeletal Oncology Group (EAMOG). Results. A total of 232 patients were enrolled (116 males and 116 females), with a median age of 50 years at diag- nosis; 25 (10.8 %) patients exhibited initial metastasis. Median follow-up was 52 months for survivors. We ob- served 102 osteolytic and mixed radiographic findings for 173 lesions. Histological subtypes other than osteoblastic type were frequent. Radiation-associated OSA was seen in seven patients, with a 5-year overall survival (OS) of 16.7 %. No Paget’s OSA was observed. High-grade spi- nopelvic OSA was seen in 29 (12.5 %) patients. The 5-year OS was 59.4 % in patients without initial metastasis and 45.2 % in patients with spinopelvic OSA. While surgery and initial metastasis were common prognostic factors for OS, chemotherapy was not. Histologic response to neoad- juvant chemotherapy was poor in 61 of 83 patients. Conclusion. This study revealed distinct clinicopatho- logical features of OSA patients over 40 years of age compared with younger patients, such as the high incidence of axial tumors, common osteolytic and mixed radio- graphic findings, the high frequency of unusual histologic subtypes, and poor prognosis. Contrary to Western elderly patients with OSA, there was no Paget’s OSA in this study, which may result in a lower incidence of secondary OSA. Prognostic factor analyses demonstrated chemotherapy did not influence OS. Osteosarcoma (OSA) has two peaks of incidence. The major peak occurs in early adolescence, with a definite second peak in elderly populations. 1,2 The age of OSA patients is increasing 1–3 and elderly patients with OSA are not uncommon. The proportion of patients over 40 years of age is 13–30 % of all OSA patients. 4,5 Although some studies have described the clinicopathological features and prognostic factors, many issues remain. Ó Society of Surgical Oncology 2015 First Received: 26 November 2014 Y.-G. Chung, MD, PhD e-mail: ygchung@catholic.ac.kr Ann Surg Oncol DOI 10.1245/s10434-015-4414-6