Phase I clinical trial of percutaneous cryoablation for osteoid osteoma.

Purpose: This prospective phase I trial was conducted to evaluate the safety of percutaneous cryoablation for osteoid osteoma (OO).
Materials and Methods: Nine patients with OO (mean tumor size: 5.9 mm; tibia, n = 5; femur, n = 2; lumbar spine, n = 2) were enrolled and treated with percutaneous cryoablation. The primary endpoint was the evaluation of the treatment safety as determined using step-by-step registration. The secondary endpoints were the incidence and grade of adverse events by CTCAE version 4.0, and the short-term efficacy of this treatment. Based on a decrease in the numerical rating scale (NRS) score, efficacy was classified as significantly effective (SE ≥ 5 or reached 0-2), moderately effective (ME 2-4), or not effective (NE < 2 or increase).
Results: Cryoablation procedures were completed in all patients. Major adverse events (≥ grade 3) related to the procedure were not observed. Minor adverse events (≤ grade2) were observed in 22-67%. The mean NRS score was 7 before treatment, 0.6 at 4-week, 0.1 at 6-month, and 0 at 1-year post-treatment. All procedures were classified as SE.
Conclusion: Percutaneous cryoablation is a safe treatment for OO. Future phase II trials with large patient cohorts are warranted.