Clinical Outcomes after Pulmonary Cryoablation with the Use of a Triple Freeze Protocol

Purpose: To elucidate clinical variables associated with safety and efficacy in patients after cryoablation of pulmonary tumors with the use of a triple freeze protocol.

Materials and methods: Percutaneous cryoablation of pulmonary tumors was performed using Galil Medical cryoprobes (Arden Hills, Minnesota) with a triple freeze protocol: 67 nodules in 42 patients were treated at a single institution from 2012 to 2016. Average nodule diameter was 1.6 cm (range 0.4-5.9); 13 nodules (19.4%) were pathologically determined to be a primary lung malignancy, whereas 54 (80.6%) were metastatic nodules of extrapulmonary origin. Average patient age was 68.1 years (range 39.6-89.6), and the male-female ratio was 1.3:1. Ipsilateral thoracic surgery, intervention, or radiotherapy had been performed before the first cryoablation in 18 patients (42.9%). Mean imaging follow-up was 326 days (range 9-1,152).

Results: Pneumothorax occurred in 19 cases (33.9%), 7 (12.5%) requiring chest tube, the likelihood of which was significantly greater in patients with 3 or more cryoprobes (P < .01). Local tumor recurrence/residual disease occurred in 6 cases (9.0%). Local tumor recurrence was not seen after ablation of nodules measuring <1.0 cm at the time of procedure, a significant difference from the recurrence ratee of 14.3% for nodules measuring ≥1.0 cm (P < .05). Likelihood of tumor recurrence/residual disease did not correlate with tumor pathology, tumor location, or procedural factors. The estimated marginal probabilities of local recurrence were 11.4%, 11.4%, and 38.1% at 1, 2, and 3 years after ablation, respectively.

Conclusions: Cryoablation of pulmonary tumors with the use of a triple freeze protocol is a viable modality with low recurrence and complication rates.