en Orthopedy Original Article Original Article <span style="font-size:14px;"><span style="font-family:Times New Roman;"><span style="line-height:14pt"><b><i><span style="color:blue">Background</span></i></b><i><span style="color:blue">:</span></i> Epidemiological characteristics of bone sarcomas are variant in different populations, however, there is no previous study on primary bone sarcomas among Iranian population. This study aimed to evaluate the incidence, age, sex distribution, histologic type, and location of malignant bone sarcomas, based on the Iran National Cancer Registry (INCR).<span style="font-size:9.0pt"></span></span><br> <span style="line-height:14pt"><b><i><span style="color:blue">Methods:</span></i></b> This was a national population-based study using INCR data from March 20, 2008, to March 20, 2015, on patients who were diagnosed with primary bone sarcomas of the appendicular (C-code:40) and axial skeleton (C-code 41), excluding skull and face bones. Primary bone sarcomas were classified according to the International Classification of Diseases for Oncology (ICD-O-3: C40&ndash;C41).</span><br> <span style="line-height:14pt"><b><i><span style="color:blue">Results:</span></i></b> A total of 4112 patients (59.5% males and 40.5% females) with a mean age of 36 years were included in the study. 60.38% of patients were between 10 to 44 years old. The overall age-standardized incidence rates&nbsp;(ASIR) was 8.23 (males=9.67 and females=6.80) per million person-years. Osteosarcoma chondrosarcoma and Ewing sarcoma were the three main histology subtypes with the ASIR of 2.36, 1.26, and 1.08 per million person-years. Long bones of the lower limb were the most affected area, with the ASIR of 3.18 (95% CI: 3.02-3.33) per million. We found an increasing trend in the incidence of bone sarcomas in Iran from 8.59 in 2007 to 11.37 per million person-year in 2015.<b><i><span style="color:blue"></span></i></b></span><br> <span style="line-height:14pt"><b><i><span style="color:blue">Conclusion</span></i></b><i><span style="color:blue">:</span></i> This study provided the epidemiological features of bone sarcomas, including the histological type of sarcoma, tumors&rsquo; location, and patients&rsquo; age and gender in the Iranian population for the first time.<b><i><span style="color:#0033cc"></span></i></b></span></span></span><br> &nbsp; Osteosarcoma, neoplasms, bone tissue, epidemiology, incidence 741 748 http://caspjim.com/browse.php?a_code=A-10-2367-1&slc_lang=en&sid=1 Adel Ebrahimpour adel.ebrahimpour@yahoo.com 100319475328460039862 100319475328460039862 No Cancer Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran Mehrdad Sadighi mehrdad_1330@yahoo.com 100319475328460039863 100319475328460039863 No Cancer Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran Amin Karimi aminkarimi79@yahoo.com 100319475328460039864 100319475328460039864 No Department of Orthopedic Surgery, Taleghani Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran Amir Sabaghzadeh dramirsabbaghzadeh@gmail.com 100319475328460039865 100319475328460039865 No Department of Orthopedic Surgery, Shohadaye Tajrish Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran Farsad Biglari biglari.farsad@gmail.com 100319475328460039866 100319475328460039866 No Department of Orthopedic Surgery, Shohadaye Tajrish Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran Mohammadreza Chehrassan morchehrasan@yahoo.com 100319475328460039867 100319475328460039867 No Cancer Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran Mehdi Azizmohammad Looha mehdi.looha@gmail.com 100319475328460039868 100319475328460039868 No Department of Biostatics, Faculty of Paramedical Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran Meisam Jafari Kafiabadi dr.jafari8567@yahoo.com 100319475328460039869 100319475328460039869 Yes Department of Orthopedic Surgery, Shohadaye Tajrish Hospital, Shahid Beheshti University of Medical Sciences, Tehran, Iran Mohammad Esmaeil Akbari me-akbari@sbmu.ac.ir 100319475328460039870 100319475328460039870 No Department of Biostatics, Faculty of Paramedical Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran Amin Nokhostin-Ansari 100319475328460039871 100319475328460039871 No Sports Medicine Research Center, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, Iran