Lizhi Niu, M.D., Kecheng Xu, M.D.*, Weibing He, M.D., Yisong He, M.D., Jiansheng Zuo, M.D.
Cryosurgery Center for Cancer, Fuda Cancer Hospital Guangzhou, Guangzhou 510300, China

*Corresponding Author: Kecheng Xu, M.D., Email: xukc@vip.163.com

Introduction

Endobronchial cryoablation has been used to treat the patients with inoperable obstructive central bronchial lung tumors and showed effective in reopening obstructed airways. Direct cryoablation has recently been applied for unresectable lung tumors, showing encouraging results.

Between March 2001 and December 2007, 1120 patients with lung cancer were treated with cryoablation in our hospital. This study describes the results of percutaneous cryoablation for the treatment of locally advanced non-small cell lung cancer in an attempt to determine the efficacy and safety of this therapeutic modality.

Technique

A total of 840 patients with non-small cell lung cancer who underwent percutaneous cryoablation were enrolled in the retrospective analysis. Based on the TNM staging, there were 122 patients with stage IIa, 462 with IIb, 160 with IIIa, 64 with IIIb and 32 with IV. All the patients were evaluated thoroughly and were considered to have unresectable tumors.

Percutaneous cryoablation was performed under guidance of CT. After local anesthesia, a 21-gauge guiding needle was percutaneously inserted into the center of the targeted tumors under fluoroscopic guidance, and when it was verified to be in the optimal position, a stainless-steel sheath, which consisted of an inner guiding sheath and an external sheath, was inserted over the needle, followed by the removal of the inner sheath. Either 2mm or 3mm cryoprobe was then inserted through the external sheath until the tip of the cryoprobe reached the end of the sheath as confirmed by CT imaging study. Using argon-helium driven cryosurgical system (Cryocare Surgical System, Endocare, Inc., USA), 2 cycles of the freezing/thawing were performed on the basis of the Joule-Thompson principle. Every cycle consisted of 15 minutes of freezing followed by 10 minutes of thawing. The freezing continued until the ice-ball was large enough to cover entire tumor. For larger tumors, multiple cryoprobes were made with the aim to destroy visible tumor. A 5-10 mm margin of normal lung tissue was included in the freezing process. Because the air prevents conduction of low temperature and there is not enough water in the lung parenchyma, the initial freezing is unable to make an ice ball which extends 1 cm beyond the tumor margin. The thawing of the first cycle causes intra-alveolar bleeding, which excludes the air, allowing the formation of a larger ice ball during the following freezing.

The use of cryoprobe should be suitable for different size of tumors. Generally, the 2 or 3mm cryoprobe will freeze tumors of 2-3cm in diameter. For the tumor larger than 3cm in diameter, two or more probes were used simultaneously. Individual tumors may be frozen sequentially on a tumor-by-tumor basis or simultaneously. Hemostasis of the insertion hole of the cryoprobe was achieved by Sponge application to the tract of the cryoprobe and by suture of the insertion site.

Results

A total of 1174 procedures of cryoablation were performed for 840 patients with lung cancer. There were 140 and 66 patients who underwent additional single and two sessions of cryoablation procedure, respectively, for recurrent tumors in the lungs. There were 62 patients who underwent additional session of cryoablation for liver metastases. During the follow-up, CR was observed in 86 patients (14.4%), PR in 588 patients (70.0%), SD in 115 patients (13.7%) and PD in 51 patients (6.1%). The recurrence rate was 47.2% during a median follow-up of 34 months (a range of 4-63). The lungs were the main area of recurrence. Extrahepatic recurrence was mainly seen in liver, brain and bone. The recurrence at cryosite, including at cryosite only as well as cryosite and the remaining area of lungs, accounted 28.3% of the cases who had recurrence and 10.8% of all cases. The median survival of all patients was 23 months (range 5-61 months). Four hundred and ninety six patients (59.0%) died during the follow-up and 344 patients (41.0%) are alive. Overall 1, 2, 3, 4 and 5 year survival rates were 68%, 52%, 34%, 26% and 21%, respectively. Patients with tumor smaller than 3 cm or located in the peripheral area had higher survival rate. Patients who underwent two procedures of cryoablation had an increased survival as compared to patients who received one time of cryoablation only. There was no intra-cryoablation mortality. The main complications were pneumothorax (218 patients, 25.9 %), pleural effusion (136 patients, 16.2%) and hemoptyxis (189 patients, 22.5%). There were a few patients who had palsy of upper limbs, abscess in cryosite, exacerbation of poor pulmonary reserve and acute myocardial infarction. A total of 22 patients (2.6%) died within 30 days post-ablation.

Conclusion

Percutaneous cryoablation offers an effective therapy for patients with advanced non-small cell lung cancer, without serious complications, and is especially suitable for treatment of unresectable lung tumors. According to our data, the percutaneous cryoablation, a feasible and mini-invasive technique, demonstrated an encouraging efficacy in the treatment of advanced non-small cell lung cancer.