Cryoablation Protocols for Primary and Metastatic Lung Tumors: A Systematic Review and Meta-Analysis Evaluating Effectiveness and Safety of Percutaneous Cryoablation of Pulmonary Tumors

PURPOSE: To evaluate 1-year local tumor control (LTC) after percutaneous cryoablation for lung tumors and to identify procedural protocol and patient/tumor characteristics associated with improved outcomes. MATERIALS AND METHODS: A systematic search of PubMed, Embase, and Web of Science was conducted. The primary outcome was LTC at 1 year. Secondary outcomes included the identification of factors associated with LTC and pooled adverse event rates, such as freezing lengths, number of cycles, tumor characteristics, and more. Data were pooled using a random-effects model, and meta-regression was used to analyze factors affecting LTC. RESULTS: Nineteen studies (786 patients, 1,048 tumors) yielded a pooled 1-year LTC of 90.5% (95% CI, 85.1%-94.1%). Multivariate meta-regression showed that smaller tumor size was significantly associated with improved LTC. Univariate analysis also identified that superior LTC was associated with a triple freeze-thaw protocols (vs double), a shorter first freeze duration, a longer final freeze duration, and ending the procedure with a thaw cycle. The incidence of adverse events (Common Terminology Criteria for Adverse Events [CTCAE] Grade ≥3) was 4.9% (95% CI, 2.9%-6.9%), with pneumothorax most common (28% of cases). CONCLUSIONS: Percutaneous cryoablation demonstrates high effectiveness for lung tumor control. Superior 1-year LTC is associated with smaller tumor size and a triple freeze-thaw protocol characterized by a short initial freeze followed by longer subsequent freezes. These findings provide a data-driven basis for standardizing cryoablation techniques.