Short-course regimen of palliative radiotherapy in complicated bone metastases: a phase i-ii study (SHARON Project)

Metastases with soft tissues invasion, impending fractures or spinal cord compression (complicated bone metastases) represent a common clinical problem in advanced cancers and frequently lead to deterioration of patients' quality of life (QoL). A phase I-II study was planned to define the maximum tolerated dose (MTD) of a short-course radiotherapy (RT) and its efficacy in palliation of complicated bone metastases. A phase I trial was designed with three dose-escalation steps: 16, 18, and 20 Gy. Total dose at each level was delivered in 2 days, twice daily. Eligibility criteria were painful complicated bone metastases and ECOG performance status ≤ 3. The presence of acute toxicity ≥ Grade 3 (RTOG scale) was considered the dose limiting toxicity. The MTD was used to plan a phase II trial with pain response as the primary outcome. Pain was recorded using a Visual Analogic Scale (VAS), and QoL using CLAS scales. Forty-five patients were enrolled in this trial. In phase I no Grade ≥ 2 acute toxicities were recorded. Thus 20 Gy was established as MTD. In phase II, with a median follow-up of 4 months, rates of complete symptom remission, partial response, no symptomatic change, and symptoms progression were 32.0%, 52.0%, 8.0%, and 8.0%, respectively. This RT protocol tested in our study is effective and tolerable with comparable results to traditional RT treatments delivered in 5-10 daily fractions.