Purpose
To assess clinical outcome and the role of proton-therapy (PT) for local control (LC) of osteosarcoma (OSA).
Methods
All patients who received PT or mixed photon-proton radiotherapy from 1983–2009 at the Massachusetts General Hospital were reviewed. Criteria for PT were the need for high dose in the context of highly conformal radiotherapy of unresected or partially resected OSA, positive postoperative margins, postoperative imaging studies with macroscopic disease, or incomplete resection as defined by the surgeon. The primary endpoint was local control (LC) of the site treated; secondary endpoints were disease-free survival (DFS), overall survival (OS), long term toxicity, and prognostic factors associated with clinical outcome.
Results
55 patients with a median age of 29 (2 to 76) were offered PT. The mean dose was 68.4 Gy, (standard deviation 5.4 Gy). 58.2% (11–100%) of the total dose was delivered with protons. LC after three and five years was 82 % and 72 %, respectively. The distant failure rate was 26% after three and five years. The five-year DFS was 65%, and the five-year OS was 67%. The extent of surgical resection did not correlate with outcome. Risk factors for local failure were ≥2 grade disease (p<0.0001) and total treatment length (p=0.008). Grade 3–4 late toxicity was seen in 30.1 % of patients. One patient died from treatment-associated acute lymphocytic leukemia, and one from secondary carcinoma of the maxilla.
Conclusion
PT to deliver high RT doses allows organ-preserving locally curative treatment with high doses for unresectable or incompletely resected OSA.
