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: This systematic review and meta-analysis aimed 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.

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, 1048 tumors) yielded a pooled 1-year LTC of 90.5% (95% CI, 85.1%-94.1%). Multivariable meta-regression showed that smaller tumor size was significantly associated with improved LTC. Univariable 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 (CTCAE Grade ≥3) was 4.9% (95% CI: 2.9%-6.9%), with pneumothorax most common (28% of cases).

Conclusion: 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.