Carbon ion radiotherapy for unresectable localized axial soft tissue sarcoma

Abstract Carbon ion radiotherapy is known for its high‐precision dose distribution and high biological effectiveness. We evaluated the results of carbon ion radiotherapy in 128 patients with unresectable localized axial soft tissue sarcoma at a single institution. The patients’ median age was 54 years, and the median follow‐up period was 49.4 (range 6.4‐146.4) months. The median tumor volume was 356 cm3. The 5‐year local control, overall survival, and disease‐free survival rates were 65%, 46%, and 39%, respectively. In the univariate analysis, tumor volume, local control, and incidences of metastases were significantly related to overall survival. In the multivariate analysis, tumor volume and local control were significantly related to overall survival. We did not find any factors related to local control. Five patients required surgical intervention because of adverse events in the bones. Carbon ion radiotherapy may be a treatment option for unresectable axial soft tissue sarcoma.