Biological 18[F]-FDG-PET image-guided dose painting by numbers for painful uncomplicated bone metastases: A 3-arm randomized phase II trial.

Background: Antalgic radiotherapy for bone metastases might be improved by implementing biological information in the radiotherapy planning using (18)F-FDG-PET-CT based dose painting by numbers (DPBN).

Materials And Methods: Patients with uncomplicated painful bone metastases were randomized (1:1:1) and blinded to receive either 8Gy in a single fraction with conventionally planned radiotherapy (arm A) or 8Gy in a single fraction with DPBN (dose range between 610Gy and 10Gy) (arm B) or 16Gy in a single fraction with DPBN (dose range between 1410Gy and 18Gy) (arm C). The primary endpoint was overall pain response at 1month. The phase II trial was designed to select the experimental arm with sufficient promise of efficacy to continue to a phase III trial.

Results: Forty-five patients were randomized. Eight (53%), 12 (80%) and 9 patients (60%) had an overall response to treatment in arm A, B and C, respectively. The estimated odds ratio of overall response for arm B vs. A is 3.5 (95% CI: 0.44-17.71, p=0.12). The estimated odds ratio of arm C vs. A is 1.31 (95% CI: 0.31-5.58, p=0.71).

Conclusion: A single fraction of 8Gy with DPBN will be further evaluated in a phase III-trial.