Carbon ion radiotherapy for inoperable pediatric osteosarcoma

// Osama Mohamad 1, 2 , Reiko Imai 1 , Tadashi Kamada 1 , Yuki Nitta 1 , Nobuhito Araki 3 and the Working Group for Bone and Soft Tissue Sarcoma 1 Research Center Hospital for Charged Particle Therapy, National Institute of Radiological Sciences, National Institutes for Quantum and Radiological Science and Technology, Chiba, Japan 2 University of Texas Southwestern Medical Center, Department of Radiation Oncology, Dallas, Texas, USA 3 Ashiya Municipal Hospital, 3 9-1 Asahigaoka, Ashiya City, Hyogo, Japan Correspondence to: Reiko Imai, email: Imai.Reiko@qst.go.jp Keywords: carbon ion; radiotherapy; charged particles; pediatric; osteosarcoma Received: January 20, 2018      Accepted: March 30, 2018      Published: May 01, 2018 ABSTRACT Background: Unresectable pediatric osteosarcoma has poor outcomes with conventional treatments. Results: Twenty-six patients aged 11–20 years (median 16) had inoperable osteosarcoma of the trunk (24 pelvic, 1 mediastinal and 1 paravertebral) without any other lesion at initial examination. There were 22 primary, 1 locally recurrent and 3 metastatic cases. Median CIRT dose was 70.4 Gy RBE (relative biological effectiveness) delivered in 16 fractions. Median follow-up was 32.7 months. Overall survival was 50.0% and 41.7% at 3 and 5 years, respectively. Ten patients survived for more than 5 years (range 5–20.7 years). Local control was 69.9% and 62.9% at 3 and 5 years, respectively and progression-free survival was 34.6% at 3 and 5 years. Only largest tumor diameter correlated with 5-year overall survival and local control. There were 4 grade 3-4 CIRT-related late toxicities, 1 case of bone fracture and no treatment-related mortalities. All patients (except 1) were able to ambulate after CIRT. Conclusions: CIRT was safe and efficacious in the treatment of inoperable pediatric osteosarcoma with improved local control and overall survival compared to conventional treatments. Methods: We retrospectively reviewed the records of pediatric and adolescent patients who received carbon ion radiotherapy (CIRT) for inoperable osteosarcoma between 1996 and 2014.