Radiation osteitis: incidence and clinical impact in the setting of radiation treatment for soft tissue sarcoma.

OBJECTIVE: Radiotherapy is an important component of soft tissue sarcoma management. Radiation osteitis is a common radiographic finding identified in the setting of radiotherapy on magnetic resonance imaging (MRI). This study aims to identify the incidence of radiation osteitis in patients who received radiotherapy for soft tissue sarcoma and if a further workup, including a biopsy, was performed for concerning MRI findings. MATERIALS AND METHODS: Medical records of patients with soft tissue sarcoma who received radiotherapy from 2008 to 2020 were retrospectively reviewed. Patients with at least one MRI of the sarcoma site following radiotherapy and information regarding radiotherapy treatments were included. MRIs of these patients were reviewed for the presence of radiation osteitis by two musculoskeletal radiologists. The clinical course of these patients including biopsy for concerning MRI findings, local recurrence, and metastasis was recorded. RESULTS: Thirty soft tissue sarcoma patients who received radiation for soft tissue sarcoma were included. Radiation osteitis was present in 18 patients. The time to osteitis present on MRI following radiotherapy completion was a median of 4.5 months. Biopsy for concerning MRI findings was performed in eight patients, five for local recurrence, and three for regional osseous metastasis. Three patients had confirmed osseous metastases. CONCLUSION: Although radiation osteitis is often a benign imaging finding, it can be difficult to discern these lesions from potentially malignant sites of disease. We recommend multidisciplinary management of soft tissue sarcoma at sarcoma centers to appropriately identify benign from malignant lesions and decide the necessity of a biopsy.