Multicenter Study of Metastatic Lung Tumors Targeted by Interventional Cryoablation Evaluation (SOLSTICE)

Objective: To assess the safety and local recurrence-free survival in patients after cryoablation for treatment of pulmonary metastases. Methods: This multicenter, prospective, single-arm, phase 2 study included 128 patients with 224 lung metastases treated with percutaneous cryoablation, with 12 and 24 months of follow-up. The patients were enrolled on the basis of the outlined key inclusion criteria, which include one to six metastases from extrapulmonary cancers with a maximal diameter of 3.5 cm. Time to progression of the index tumor(s), metastatic disease, and overall survival rates were estimated using the Kaplan–Meier method. Complications were captured for 30 days after the procedure, and changes in performance status and quality of life were also evaluated. Results: Median size of metastases was 1.0 plus or minus 0.6 cm (0.2–4.5) with a median number of tumors of 1.0 plus or minus 1.2 cm (one to six). Local recurrence-free response (local tumor efficacy) of the treated tumor was 172 of 202 (85.1%) at 12 months and 139 of 180 (77.2%) at 24 months after the initial treatment. After a second cryoablation treatment for recurrent tumor, secondary local recurrence-free response (local tumor efficacy) was 184 of 202 (91.1%) at 12 months and 152 of 180 (84.4%) at 24 months. Kaplan–Meier estimates of 12- and 24-month overall survival rates were 97.6% (95% confidence interval: 92.6–99.2) and 86.6% (95% confidence interval: 78.7–91.7), respectively. Rate of pneumothorax that required pleural catheter placement was 26% (44/169). There were eight grade 3 complication events in 169 procedures (4.7%) and one (0.6%) grade 4 event. Conclusion: Percutaneous cryoablation is a safe and effective treatment for pulmonary metastases.