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