Lizhi Niu,M.D.,Ph.D.,Kecheng Xu,M.D., Weibing He,M.D., Yisong He,M.D.,Jiansheng Zuo,M.D.

ABSTRACT

Background.The purpose of this study was to determine the effectiveness of percutaneous cryoablation for locally advanced non-small cell lung cancer.

Methods. A total of 840 patients with non-small cell lung cancer who underwent percutaneous cryoablation was enrolled in the retrospective analysis.The TNM staging was: stage IIa 122 patients，
IIb 462 patients, IIIa 160 patients, IIIb 64 patients and IV 32 patients.
Histology was confirmed as squamous cell carcinoma (392
patients), adenocarcinoma (411 patient) and large cell carcinoma
(37 patients). The tumors of all cases received a thorough investigation and were considered as unresectable. Percutaneous cryoablation was performed under guidance of CT. Using argon-helium system (Endocare, CA,USA) 2-3 cycles of the freezing/thawing were performed on the basis of the Joule-Thompson principle. The freezing continued until the ice-ball was large enough to cover 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. It is necessary to perform at least 2 -3 sessions of cryoablation procedure.

Results. A total of 1174 procedures of cryoablation was performed in 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 (range, 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 cases who had recurrence and 10.8% of all cases.The median survival of all patient was 23 months(range 5-61 months).496 patients (59.0%) died during the follow-up and 344 patients(41.0%) are alive, with a median survival of 19 and 32 months, respectively. 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, tumor located in 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 which was seen in 218 patients(25.9 %), pleural effusion,which was observed in 136 patients(16.2%), and hemoptyxis, which occurred in 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 post-ablation 30 days..

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

Key words.lung cancer, cryosurgery, percutaneous cryoablation

Pulmonary carcinoma has become the most common cause of death from malignant disease in the world. Due to this late presentation, about 85% of patients are in an advanced stage of the disease at diagnosis. overall 5-year survival is only 15%[1]. These figures have changed little over recent years, in spite of advances in radiotherapy and chemotherapy.

Surgical resection is the only modality which offers curative possibility of this disease, but only around 20% of the patients diagnosed with lung cancer are considered resectable. Of patients with operable tumors, about 20% are unable to undergo radical resection because of poor respiratory function or other major organ dysfunction[2].

During the past years, endobronchial cryoablation has been used to treat patients with inoperable obstructive central bronchial lung tumors and showed effective in reopening obstructed airways [3,4].Direct cryoablation recently has been applied for unresectable lung tumors, showing encouraging results[4].

Between March 2001 and December 2007, 1120 patients with lung cancer were treated by cryoablation in our hospital. This study describes the results of percutaneous cryoablation for the treatment of locally advanced lung cancer with the purpose of determining the efficacy and safety of this modality.

PATIENTS AND METHODS

Patients
A total of 840 patients with non-small cell lung cancer who underwent percutaneous cryoablation was enrolled in the retrospective analysis. There were 603 males and 237 females with a median of 61 years (range 34 to 85 years).

The TNM staging was: stage IIa 122 patients，IIb 462 patients, IIIa 160 patients, IIIb 64 patients and IV 32 patients.Histology was confirmed as squamous cell carcinoma (392 patients), adenocarcinoma (411 patient) and large cell carcinoma (37 patients). The tumors of all cases received a thorough investigation including chest radiograph; CT scan of the thorax and abdomen; respiratory function tests,including diffusion factors and spirometry, with regard to the presence of multiple nodules or to the presence of a large and/or ill-located tumor, comorbidity, and were considered as unresectable. The patients with extra-lung metastases or respiratory failure and small cell lung cancer were not enrolled in this study.

Table 1 Characteristics of 840 patients with lung cancer

Cryoablation technique
Percutaneous cryoablation was performed under guidance of CT[5,6]. After local anesthesia, a 21-gauge guiding needle was percutaneously inserted into the center of the targeted tumors after fluoroscopic guidance, and it was proved 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. The inner sheath was removed, then either a 2-mm or 3-mm cryoprobe was inserted through the external sheath, and it should be confirmed that the cryoprobe tip located at the end of the sheath by CT imaging study. Using argon-helium system (Endocare Cryocare System, CA,USA) 2-3 cycles of the freezing/thawing were performed on the basis of the Joule-Thompson principle. Every cycle was consisted of 15 minutes of the freezing and the following 10 minutes of the thawing. The freezing continued until the ice-ball was large enough to cover 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, initial freezing cannot make an ice ball which extend 1 cm around tumor. The thawing of the first cycle of freezing induces intra-alveolar bleeding, which excludes the air, hence the larger ice ball is formed during the folowing freezing.

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

Follow-up
Postoperative follow-up was obtained at 1 month and every 4 months thereafter by assessment of chest CT. Some of patients received follow-up with PET-CT. Efficacy of cryoablation was evaluated according to the evolution of tumor size. Changes in tumor mass were measured according to the Response Evaluation Criteria in Solid Tumors (RECIST) protocol [7],which based on objective measurements of lesion size before and after treatment. Complete response(CR) means cryotreated lesion disappearance (scar) or less than 25% of original size. Partial response(PR) means a greater than 30 % decrease in the sum of the largest diameter of all targeted lesions. Stable disease (SD) means less than 30% decrease in the sum of the largest diameter of all targeted lesions. Progressive disease(PD) means an increase of greater than 20% in the sum of the largest diameter of all targeted lesions.

All radiologic studies were reviewed by the same radiologist with a expertise in chest imaging. For lesions suspecious of recurrence, an CT-guided lung biopsy was performed for histologic study. Subsequent re-cryoablation was performed if histology showed positive result. A persistent nodule on radiologic imaging with no changes in the absence of other treatment for an interval of at least 6 months since cryoablation, or without tumor activity shown on PET-CT,was considered as a remnant. Tumor recurrence was estimated either by histologic examination of the lungs, or by size increase of the cryotreated lesion on X-ray firm, CT or PET-CT imagings.

Statistical analysis
Survival was determined according to the Kaplan-Meier method. Comparison of survival rates was obtained with the log-rank test. A p value lower than 0.05 was considered statistically significant.

RERULTS

A total of 1174 procedures of cryoablation was performed in 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.

Evolvement in tumor size
After cryoablation, early increase in the size of lesions in relation to the freezing margin exceeding 1 cm beyond the limit of the tumor was a constant feature.And then, cryotreated lesions appeared as shrinking or cavitation on CT. 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%). Here are presented CT scan of three patients with complete response proved by histology as in Figure 1,2,3.

Firgue 1 The CT scan of lungs of patient with right lung cancer. Complete ablation of tumor was achieved after percutaneous cryoablation.(A)Before cryoablation.(B)During percutaneous cryoablation under CT guidance.(C)Twelve months after cryoablation. The ablation of lesion was proved by histology

Figure 2 CT scan of a patient with right lung cancer treated by percutaneous cryoablation. The massive lesion showed a complete response to cryoablation. (A)Before cryoablation.(B) Eight months after cryoablation. The lesion was ablated totally.

A	B

Figure 3 CT scan of a patients with right central lung cancer underwent percutaneous cryoablation.(A)Before cryoablation.(B)During cryoablation under CT guidance
Tumor recurrence

Table 3 Recurrence pattern at death or latest follow-up

Overall survival
During follow-up, the median survival of all patient was 23 months(range 5-61 months).496 patients (59.0%) died during the follow-up and 344 patients(41.0%) are alive, with a median survival of 19 and 32 months, respectively. Overall 1-,2-,3-,4-,and 5-year survival rates were 68%, 52%,34%, 26% and 17%, respectively. Patients with tumor smaller than 3 cm in size, tumor located in peripheral area, had higher survival rate. There was no significant difference in survival based on number of the tumors and pre-cryoablation chemotherapy(Table 4).

Table 4 Survival based on patient characteristics and tumor features

*p <0.01

Figure 4 Survival rates of patients with lung cancer

To some extent, the survival was related to the number of cryoablation procedure performed on the patients. Patients who underwent two procedures of cryoablation had an increased survival as compared to patients who received one time of cryoablation only (P<0.01). However, the patients who received cryoablation of two and more than two sessions had the lower survival, possibly in relation with more severe disease in the patients of the subgroup (figure 4).

Mortality and morbidity
There was no intra-cryoablation mortality. The main complication was pneumothorax which was seen in 218 patients(25.9 %).Most of them were recovered with air aspiration with needle, and there no patient with bad outcome. Pleural effusion was observed in 136 patients(16.2%), in whom 87 patients had only a small amount of effusion detected on CT, and no additional management was required.Hemoptyxis occurred in 189 patients(22.5%) and subsided in 5-7 days in majority of the patients.32 patients had palsy of upper limbs, which was resulted from damage of arm nerves during cryoablation of tumors in upper part of the lungs. All patients had recovery spontaneously within 6 months after cryoablation. Abscess in cryosite occurred in 9 patients, in whom 9 patients had abscess disappearance with antibiotics and one patient had persistent infection with death outcome. The pulmonary function had exacerbation in 39 patients who had poor pulmonary reserve before cryoablation. Of them,21 patients had recovery with assistant respiration, and 18 died of pulmonary failure. There were 4 patients who occurred acute myocardial infarction, and 3 of them died of heart failure and cardiac shock. In summary, during 30 days after cryoablation, a total of 22 patients (2.6%) died of one of above complications.

Table 5 Complications within 30 days after cryosurgery

DISCUSSION
Locally advanced non-small cell lung cancer comprises mainly includes stage IIa, IIb, IIIa and IIIb of lung cancer, with very prognosis. No clear-cut consensus regarding the management of this disease has been established worldwide as of yet. Single-modality treatment such as chemotherapy,radiotherapy or surgery alone showed disappointing results,and therefore some new therapies have been investigated for this disease[8].

There are few options available when lung cancer is considered unresectable. Cryosurgery is one of promising techniques. In view of experience with endobronchial and direct cryoablation for lung cancer[3,4] and the successful results of percutaneous cryoablation of liver and prostate carcinoma[9,10], we decided to try the use of percutaneous cryoablation for lung tumor masses under CT guidance.

Efficacy of percutaneous cryoablation
Our data showed that after percutaneous cryoablation, tumors of the lung cancer had CR 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 median survival of all patient was 23 months (range 5-61 months).496 patients (59.0%) died during the follow-up and 344 patients(41.0%) are alive, with a median survival of 19 and 32 months, respectively. Overall 1-,2-,3-,4-,and 5-year survival rates were 68%, 52%,34%, 26% and 21%, respectively.

The efficacy of cryoablation above mentioned is much better than that of chemotherapy with or without radiation in recent reports. In a total of 417 patients reported, overall response rate was 39% with range of 26%-78%,median survival was 5-23 months (mean 13.2),mean 1-,2-,3-,4-,and 5-year overall survival rate was 28%,22.5%,22%,20% and 10%,respectively.

Table 6 Results of advanced non－small cell lung cancer in literature

RT:radiation;Chemo:chemotherapy

Factors influencing survival of patient

This study showed that patients with lesions smaller than 3 cm or peripheral location had an increased survival rate compared with those with lesions of more than 3cm and central location of tumors. The reason could be the larger tumors and the tumors of central location in the vicinity of large vessels and the exposure to the heat sink effect. Blood flowing by with a warming effect can induce the insufficient cryodestruction for tumor. Pearson[19] reported that after cryoablation for liver cancer,66.7% of local recurrence occurred directly in a large vessel.

In our patients, 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 procedure of cryoablation for liver metastases. The patients who underwent two sessions of cryoablation procedure had the highest survival.The repeat cryoablations were aimed to eradicate recurrent or metastatic lesions. It is percutaneous mode of cryoablation that has such advantage because of its simple and convenient traits, in contrast to operative cryosurgery, The repeat cryoablation permits proper eradication of new lesions, hence is helpful to increase the survival.

Because air in normal alveolar tissue prevent the formation of ice around tumor, it is difficult to form a 5-10 mm margin of normal lung tissue in the first freezing/thawing cycle. Therefore, lung cryoablation should be performed at least 2-3 times. This is different from cryoablation for other organs, that should be paid a great attention.

Safety of percutaneous cryosurgery

As lungs are a air-contained organ, pneuthorax during percutaneous lung cryoablation is a logistic complication, which was seen in 25.9% in this study. Pleural effusion and hemoptyxis are also common adverse effect,and were seen in 16.2% and 22.5% of our series. But these complications generally don't threaten the life of patient, had a recovery with conservative management or spontaneously. No severe complications such as cryoshock and renal insufficiency, which were observed after liver cryoablation[20], were seen in this series of cryoablation for lung cancer. The 30-day motality is 2.6% in this study, the reasons were lung failure, secondary infection and acute myocardial infarction, which obviously may also occur in patients who received other therapies for lung diseases. Therefore, percutaneous lung cryoablation is a safe technique.

Conclusion
Percutaneous cryoablation offers an effective therapy for patients with locally advanced non-small cell lung cancer, without serious complications. It is specially suitable for treatment of unresectable lung tumors with regard to the presence of multiple nodules or to the presence of a large and/or ill-located tumor, comorbidity, and had a therapeutic efficacy which is preponderate over that of routine chemotherapy and radiation. However, this study is preliminary. It is necessary to further determine its efficacy and role for treatment of lung cancer in respect of comparison between this modality and wedge resection, stereotactic radiation or other therapies. Nevertheless, according to current data, percutaneous cryoablation as a feasible and mini-invasive technique, has an encouraging efficacy for the treatment of advanced non-small cell lung cancer.

REFERENCES
[1]Non-small Cell Lung Cancer Collaborative Group.Chemotherapy in non-small cell lung cancer:a meta-analysis using updated data onindividual patients from 52 randomized clinical trials.Br Med J 1995;311:899
[2]De Perrot, M., Licker, M., Robert, J., Spiliopoulos, A. Time trend in the surgical management of patients with lung carcinoma. Eur J Cardiothorac Surg 1999, 15:433-437.
[3]Maiwand MO, Asimakopoulos G. Cryosurgery for lung cancer: Clinical results and technical aspects. Technol Cancer Resear Treat， 2004;3:143-150.
[4]Asimakopoulos G, Beeson J, Evans J, Maiwand MO.Cryosurgery for malignant endobronchial tumors: analysis of outcome. Chest，2005;127(6):2007-2014.
[5] Simon CJ, Dupuy D. Current role of imaging-guided ablative therapy in lung cancer. Expert Rev Anticancer Ther 2005;5:657-666
[6] Baust J,Gage AA,Ma H,et al. Minimally invasive ryosurgery—technological advances.Cryobiology 1997;34:373-384
[7]Truchida Y,Therasse P.Response evaluation criteria in solid tumors(RECIST):new guideline.Med Pediatr Oncol 2001;37:1-3
[8]Okamoto H, Watanabe K.Medical Treatment for Stage III Non-Small-Cell Lung Cancer (NSCLC). Gan To Kagaku Ryoho. 2007;34(6):841-848（Japanese）.
[9] Xu KC，Niu LZ,He WB, et al . Percutaneous cryoablation in combination with ethanol injection for unresectable hepatocellular carcinoma. World J Gastroenterol 2003;9:2686-2689.
[10] Mouravier V,Polascik TJ.Update on cryotherapy for prostate cancer in 2006.Curr Opin Urol, 2006;16:152-156
[11]Devlin JG, Langer CJ.Salvage therapy with vinorelbine in advanced non-small-cell lung cancer: a retrospective review of the Fox Chase Cancer Center experience and a review of the literature. Clin Lung Cancer. 2007;8(5):319-326.
[12]Wozniak AJ, Belzer K, Heilbrun LK, Kucuk O, Gadgeel S, Kalemkerian GP, Venkatramanamoorthy R, Kraut MJ.Mature results of a phase II trial of gemcitabine/paclitaxel given every 2 weeks in patients with advanced non-small-cell lung cancer. Clin Lung Cancer. 2007;8(5):313-318.
[13]Oshita F, Saito H, Yamada K.Feasible combination chemotherapy with nedaplatin and irinotecan for patients with non-small cell lung cancer and multiple high-risk factors. J Exp Ther Oncol. 2007;6(3):251-256.
[14]Wang LR, Huang MZ, Zhang GB, Xu N, Wu XH.Phase II study of gemcitabine and carboplatin in patients with advanced non-small-cell lung cancer. Cancer Chemother Pharmacol. 2007
[15]Yoh K, Kubota K, Kakinuma R, Ohmatsu H, Goto K, Niho S, Saijo N, Nishiwaki Y.Phase II trial of carboplatin and paclitaxel in non-small cell lung cancer patients previously treated with chemotherapy. Lung Cancer. 2007;
[16]Riedel RF, Andrews C, Garst J, Dunphy F, Herndon JE, Blackwell S, Barbour S, Crawford J.A phase II trial of carboplatin/vinorelbine with pegfilgrastim support for the treatment of patients with advanced non-small cell lung cancer. J Thorac Oncol. 2007;2(6):520
[17]Schild SE, Mandrekar SJ, Jatoi A, McGinnis WL, Stella PJ, Deming RL, Jett JR, Garces YI, Allen KL, Adjei AA; for the North Central Cancer Treatment GroupThis study was conducted as a collaborative trial of the North Central Cancer Treatment Group and the Mayo Clinic..The value of combined-modality therapy in elderly patients with stage III nonsmall cell lung cancer. Cancer. 2007: 31
[18]Shi A, An T, Zhu G, Yu R, Xu G, Liu X, Xu B.Phase I study to determine the MTD of paclitaxel given three times per week during concurrent radiation therapy for stage III non-small cell lung cancer. Curr Med Res Opin. 2007;23(5):1161-1167.
[19]Pearson AS,Izzo F,Fleming RY,Ellis LM,Delrio P,Roh MS,et al.Intraoperative radiofrequency ablation or cryoablation for hepatic malignancies.Am J Surg 1999;178:592-599
[20]Seifert JK,Morris D.World survey on the complications of hepatic and prostate cryotherapy.World J Surg 1999;23:109-114