Kecheng Xu, Lizhi Niu, Yize Hu, Weibing He, Yisong He, Jiansheng Zuo

ABSTRACT

Purpose ：To study the therapeutic value of combination of cryosurgery and 125iodine seed implantation for locally advanced pancreatic cancer. Methods: Thirty eight patients with locally advanced pancreatic cancer (male 28 cases and female 10 cases), with the median age of 57 years old, were enrolled in this study. The diagnosis of disease was based on imaging such as ultrasound, CT and MRI. Among them, 31 cases were confirmed by pathology. Ten cases had metastases of peripancreatic lymph node and 8 cases liver metastases. All the patients were considered to have unresectable tumors after being thoroughly evaluated. The therapy included cryosurgery, which was performed intraoperatively or percutaneously under guidance of ultrasound and /or CT, and 125iodine seed implantation which was performed during cryosurgery process or post-cryosurgery under guidance of ultrasound and /CT. There were a few patients who received regional celiac artery chemotherapy.

Results: Eleven patients received intraoperative cryosurgery and 27 patients received percutaneous cryosurgery. Fourteen patients underwent the second cryosurgery and 3 underwent the third cryosurgery. 125Iodine seed implantation was performed for 29 patients during cryosurgery and for 9 patients 3-7 days post-cryosurgery. Fifteen patients in which 13 had metastases of peripancreatic lymph nodes or liver received regional chemotherapy. At 3 months after therapy, CT follow-up was performed to estimate the tumor response to therapy. Most of the cases had tumor necrosis of different degree, and complete response (CR) of tumor was seen in 23.6% of patients, partial response (PR) in 42.1%, stable disease (SD) in 26.3%, and progressive disease (PD) in 7.9%. The adverse effects associated with cryosurgery mainly included pain of upper abdomen and increased serum amylase activity. Acute pancreatitis was seen in 5 patients in whom one had hemorrhagic type of pancreatitis. All adverse effects were controlled by medical management with no poor outcome. There was no therapy-related mortality. During the follow-up of median 16 months (range of 5-37), median overall survival was 12 months and there were 20 cases (52.6%) whose survival was 12 months or more. Overall 6-, 12-, 24-and 36-month survival rates were 94.7%, 49.4%, 21.8% and 5.4%, respectively. There were 4 patients who survived 24 months or more. One of the patients survived for 37 months without evidence of recurrence.

Conclusion The cryosurgery, a far less invasive procedure than conventional pancreas resection, had a low rate of adverse effects and should be considered a therapeutic procedure of choice for most of the patients with locally advanced pancreatic cancer. 125Iodine seed implantation can destroy the residual surviving cancer cells after cryosurgery. Hence, the combination of the two has a complementary effect.

Key words Pancreatic cancer cryosurgery cryoablation 125iodine seed implantation

Since 1970s, along with the imaging and molecular biology technology, the diagnosis of pancreatic cancer has improved substantially, but the survival rate has not improved significantly. Most of the patients had lost the chance of receiving radical resection by the time the diagnosis was made and palliative treatment was the only option. Overall 1-and 5-year survival rates for patients with pancreatic cancer were only 20% and 5%, respectively [1, 2]. Paclitaxel and gemcitabine have been considered to be effective agents for pancreatic cancer, but their response rates were no more than 20%, and their effectiveness lasts less than 6 months [3, 4]. Therefore, it is necessary to seek for new modality [5, 6].

We have used combination of cryosurgery and 125iodine seed implantation for the treatment of locally advanced pancreatic cancer, and achieved a better result.

PATIENTS AND METHODS
Patients
From 2001 to April 2007, thirty eight patients with locally advanced pancreatic cancer underwent cryosurgery with combination of 125iodine seed implantation. They were 28 males and 10 females, aged 29-89 years old, with a median age of 57 years. Tumor size ranged from 2.2 to 7.1cm in diameter. Ten patients had peripancreatic lymph node metastasis, and 8 patients had liver metastasis. Diagnoses in all patients were based on ultrasound, CT and MRI imagings, and there were 31 patients whose diagnoses were proved by histology. Before hospitalization, 8 cases have received 4-6 cycles of chemotherapy (gencitabine, cisplatin, 5-FU). All the patients were evaluated thoroughly and considered to have unresectable tumors.

Cryosurgery: The procedure of cryosurgery was performed with intraoperative or percutaneous approaches.

Intraoperative cryosugerry: The patients were initially administrated an inhalational anesthetic and an upper abdominal incision was then made. The involved pancreas was exposed by trans-peritoneal mobilization of the bowel and stomach. Once the specific pancreatic mass was identified, an 18-gauge Tru-Cut biopsy needle was used to obtain one to two cores of tissue from solid mass. If the tumor proved to be unresectable through a thorough investigation, cryosurgery was performed in direct vision and under the guidance of ultrasound. A variable number (one to three) of 2- or 3-mm cryoprobes were placed directly into the pancreatic mass and positioned under ultrasound guidance. Generally, lesions smaller than 3cm could be reliably frozen with a single, centrally placed, 3-mm probe, and the large lesions required multiple probes. A double cycle of freeze/thaw procedure was used with an argon gas –based cryosurgical unit (EndoCare, Inc., CA, USA). Each cryoprobe was cooled to -160 C. The resulting iceball was monitored under ultrasound. When the frozen region encompassed the entire mass of the tumor and at least 0.5-cm beyond the tumor margin (safe border), the tissue was then allowed to slowly thaw to 0 C. A second cycle of freezing/thawing was performed after necessary repositioning of the cryoprobes. After the freezing process was completed, the cryoprobes were removed and the entry site occluded with thrombin-soated Gelfoam. For the metastases of peripancreatic nodes and the liver, the cryosurgery was performed simultaneously[7, 8].

Percutaneous cryosurgery: The procedure was performed under local anesthesia and under guidance of CT. Insertion of cryoprobe was often done through the retroperitoneal approach based on the location of the tumor. Generally, the 2- or 3-mm cryoprobe was used. For the tumor more than 3cm, 2 to 3 probes may be used. For liver metastases, simultaneous cryosurgery was performed using additional cryoprobes which were inserted through right intercostal space. The cryosurgery procedure was the same as that of intraoperative cryosurgery[8].

Seed implantation: The procedure was performed during the process of cryosurgery, or was done via percutaneous approach under guidance of ultrasound or CT after cryosurgery. The 125iodine seeds were implanted at the border line of the tumor. The number of seeds depends on the size of the tumor, and individual seeds were implanted 0.5cm apart.

Postoperative management: The patients were being instructed not to eat for three days. An analogue of somatostatin was given intravenously generally for 3 -4 days, or until alleviation of abdominal pain and repristination of the elevated serum amylase levels. Aprotinin, an inhibitor of pancreatic enzymes, and a proton pump inhibitor were given intravenously in patients with abdominal pain and increased serum amylase levels.

Regional chemotherapy: Infusion of chemotherapeutic drugs was given through transcatheter of celiac artery using Seldinger technique in the patients with metastases of peripancreatic lymph nodes and liver. The medications were 5-FU 500mg/m2, mitomycin C 8.5 mg/m2 and gemcitabine 500 mg/m2, respectively. They were given once in every 2 weeks.

Follow-up
Postoperative follow-up was obtained at the one month after treatment and every 4 months thereafter by assessment of tumor markers, abdominal ultrasonography, and CT. Some of the patients received follow-up with positron emission tomography-CT (PET-C). Efficacy of cryosurgery was evaluated according to the evolution of tumor size and survival of the patients. Changes in tumor mass were measured according to The Response Evaluation Criteria in Solid Tumors (RECIST) protocol [9], which is based on objective measurements of lesion size before and after treatment. Complete response (CR) means cryotreated lesion disappeared (scar) or became 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 an expertise in pancreas imaging. For lesions suspicious of recurrence, an ultrasound-guided liver biopsy was performed for histologic study. Subsequent re-cryosurgery was performed if histology showed positive result. A persistent nodule on radiologic imaging, without tumoral activity on PET-CT, or with the reducing and normalized tumor markers (CA19-9), or no changes in size in the absence of other treatment for an interval of at least 6 months since cryosurgery, was considered as a remnant. Tumor recurrence was estimated either by positive histology, or by the combination of the increase in size of the cryotreated lesion on ultrasound, CT or PET-CT imagings and increased tumor markers or by the discovery of metastases.

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

RESULTS
Eleven patients received intraoperative cryosurgery, and 27 patients underwent percutaneous cryosurgery. Among the patients that received percutaneous cryosurgery, 14 cases received the second session of cryosurgery, 3 cases received the third session of cryosurgery. Twenty nine cases received 125iodine seeds implantation at the same time of cryosurgery, 9 cases received 125 iodine seed implantation under ultrasound and CT guidance within the 7-9 days after cryosurgery. The number of 125 iodine seeds implanted for each patient was 18 in average with a range of 18-45 seeds. Thirteen out of 15 patients with metastases either to peripancreatic lymph nodes or to the liver received regional celiac artery chemotherapy, which was performed every two weeks (as a cycle). Nine patients received 1 cycle, 7 cases 2 cycles, 3 cases 3 cycles, 2 cases 4 cycles.

Response to treatment: According to the results of CT at 3 month after treatment, the response of the tumor to treatment was shown in Table 1. For most of the patients the tumors had varying degrees of necrosis, CR, PR, SD and PD were 23.6%, 42.1%, 26.3% and 7.9%,respectively.

Table 1 Response of tumor of pancreatic carcinoma to therapy

Adverse Reactions: Seventy three point seven percent of patients had the abdominal pain, which subsided usually in 2-3 days. More than half of the patients (55.3%) had an elevated serum amylase levels, which generally ranged 1-2 times of the normal reference values and persisted for 5 -7 days. Acute pancreatitis with acute abdominal pain, elevated serum amylase levels to four times or more was seen in 5 patients (13.2%), in whom one patient developed hemorrhage-necrosis type of pancreatitis with intraabdominal fluid effusion, serum amylase levels as high as 12 times normal value. All the patients with pancreatitis were treated by conservative management. Three patients (7.9%) had intra-abdominal bleeding, however, the intra-abdominal fluid obtained by paracentesis showed no obvious increase in amylase activity. The bleeding ceased spontaneously within four days. The majority of the patients (63.2%) had fever of 38 -39.5 C, with temporary chill. Fever persisted for 3 -4 days, generally less than 7 days. Two patients had pulmonary infection, which was resolved in 7 -10 days with antibiotic therapy. There were two elderly patients (aged 78 and 91 years old, respectively) who developed cerebral infarction and myocardial infarction, respectively. No treatment-related mortality occurred.

Table 2 Adverse effects of pancreatic cryosurgery

* With abdominal pain and fever，** including 5 patients with acute pancreatitis， *** 3 patients with abdominal pain

Overall survival
During a median follow-up of 16 months (range of 5-37 months), the median of overall survival was 12 months. There were 20 patients who (52.63%) survived 12 months or more. The 6-,12-,24- and 36-momth overall survival rates were 94.7%, 49.4%, 21.8% and 5.4%, respectively for all the patients. Six patients underwent chemotherapy and their 6- and 12- month overall survival rates were 93.3% and 26.6%, respectively, and none of the patients survived beyond 24 months. There were 32 patients who did not received chemotherapy, and their 6-, 12-, 24- and 36-momth overall survival rates were 95.6%, 65.9%, 19.8% and 9.9%, respectively. Survival curve was seen in figure 1.The survival between patients undergoing chemotherapy and patients not undergoing chemotherapy was statistically significant (p <0.005). There were 29 deaths, in whom 13 died of cancer spread, 11 with liver metastases died of liver failure, 3 died of cardio - cerebral vascular diseases, 2 died of unknown causes. Among 15 patients who died within 12 months, 11 patients had metastases to liver or to peripancreatic lymph node before this treatment. There were 4 patients who survived 24 months or more, among whom one survived 31 months and another 37 months. At the time of writing the paper, the patient who survived the longest was still alive without evidence of recurrence.

Figure 1 Survival of patients with pancreatic cancer

The following are the three example cases:
Case 1. This patient is 80 years old and had an increased bowel movement of unknown etiology for 2 weeks. Ultrasound found an occupying lesion of 3 X 3 cm in size within pancreatic neck. Ultrasound-guided percutaneous biopsy showed a cystadenocarcinoma. The patient refused surgery, but was amenable to percutaneous cryosurgery with 125 iodine seed implantation under CT guidance. Three months after the treatment, CT scan was performed and found that there was tumor necrosis, which contained 125 iodine particles. The patient’s diarrhea subsided. The patient had a good sense of self and an increase in the body weight. Current ultrasound and CT scan showed that the original tumor was shrunken to 1.5 x 1.1 cm in size. The patient survived 37 months free of recurrence.

Figure 1 图2 Pancreatic CT scan in case 1. (A)Before treatment. (B) Three months after treatment. (C) 12 months after treatment

Case 2 This was a 61 years old male patient who had ultrasound and CT scan due to abdominal pain, and was found to have a tumor in pancreatic body and tail, which was proved to be adenocarcinoma by biopsy. The patient underwent chemotherapy for 4 cycles, but the tumor still exhibited a very progressive process. CT showed a low-density area of 4 X 5.5 cm in size in the body of pancreas and 3 intrahepatic lesions with sizes ranging from 2-5cm. The Serum CA19-9 was 512 IU. The patient underwent percutaneous cryosurgery and 125iodine seed implantation under guidance of CT / ultrasound for the pancreatic lesion and hepatic metastases. Repeat CT scan showed the tumor shrinkage and stability of lesions in both pancreas and liver (figure 3).Ultrasound-guided biopsy showed no evidence of cancer; CA19-9 levels were decreased to below 40 IU. The patient is alive for 24 months.

A                                     B                                  C

Figure 3 CT scan of case 2.(A)Before treatment, a mass was seen in pancreatic body and trail.(B) One month after treatment.(C) 6 months after treatment

Case 3 Male, 36 years old, complained upper abdominal pain with jaundice and weight loss for 2 weeks. Ultrasound and CT revealed the mass of pancreatic head with dilated common bile duct. Serum alkaline phosphatase activity was 650 IU, CA19-9 210 IU and CEA 28μg/L. The patient underwent laparotomy and was found to have a mass of 5 X 5 cm in size within pancreatic head. Biopsy showed moderate differentiation of adenocarcinoma. The tumor was non-resectable. The palliative cholecystojejunostomy was performed for the treatment of his obstructive jaundice, and cryosurgery was then carried out under direct vision and ultrasound guiding for the treatment of pancreatic tumor, followed by trans-celiac artery infusion of chemical agents for 4 cycles. Following the treatment, the patient had a significant improvement of his symptoms. CT follow-up was performed three months after the treatment and showed the shrinkage and necrosis of the pancreatic mass with “honeycomb”-like change (figure 4). CA19-9 was decreased to 48 IU. The patient had survival of 19 months.

A                                                  B

Figure 4 CT scan in case 3. (A) Before treatment. (B)Three months after treatment

DISCUSSION
Cryosurgery recently has provided a new therapeutic approach and has been used for the treatment of many benign and malignant tumors, especially for unresectable tumors[10]. Several publications have reported trials using the modality in the treatment of liver cancer, prostate cancer kidney tumors, breast cancer, and showed encouraging results [11, 12].

There were few reports about cryosurgery for treatment of pancreatic cancer. Kovach [13] reported that 9 patients with unresectable pancreatic cancer underwent a total of 10 sessions of intraoperative cryosurgery under ultrasound guidance. There was no cryosurgery-related mortality and no post-cryosurgery pancreatic fistulae and pancreatitis. Following the treatment, patients had alleviation of pain and decreased requirement for analgesics. All the patients were tolerated to normal diet at the time of discharge from hospital. Patiutko[14] treated 30 patients with locally advanced pancreatic cancer with combination of cryosurgery and radiation. All patients had effective control of pain, decrease in CA 19-9 levels, improvement of performance, increased survival rates. Korpan[15] summarized his experience with cryosurgery for pancreatic cancer, and concluded that there was a good therapeutic efficacy of the modality for most of the patients.

The effectiveness of cryosurgery is dependent upon the complete cryoablation of all targeted tissue. The tumor persistence or recurrence at the site of cryoablation is often resulted from an incomplete destruction. Temperatures lower than -40 °C are assumed necessary to ensure the tumor ablation. Ice-balls larger than the target lesions are thus necessary for complete tumor ablation, because the temperature at the edge of the iceball is non-lethal. The ice-ball covering entire tumor and 1.0 cm beyond the tumor borders (1 cm safe border) should be often considered as adequate for ablation [16, 17]. However, because the pancreas is a relatively small organ, the cancer often involves most of the pancreatic glands, and over-freezing would increases the chances of complications. Therefore, it is very difficult to ensure the “1 cm safe border”. Therefore, we decided to try the combination of cryosurgery with 125iodine seed implantation for the treatment of the pancreatic cancer.125Iodine has half-life of 59 days and radiates a γ ray of short distance which results in death of cancerous cells. Obviously, 125iodine seeds are a complementary to cryosurgery [18].

In this study, 38 patients with locally advanced pancreatic cancer underwent the combination of cryosurgery with 125 iodine seed implantation. There were 11 patients who underwent intra-operative cryosurgery and 27 patients who underwent percutaneous cryosurgery under guidance of ultrasound and CT. As a result, most of the tumors had necrosis of different degree, CR, PR and SD were 23.6%, 42.1% and 26.3%, respectively, and only 7.9% showed PD. During a median follow-up of 16 months (5-37 months), the median survival was 12 months for all patients, in whom 20 patients (52.63%) survived 12 months or more. The overall 6-,12-,24- and 36-momth survival rates were 94.7%, 49.4%, 21.8% and 5.4%,respectively.

At present, the conventional therapies for advanced pancreatic cancer are chemotherapy and radiation. There are diverse results in publications worldwide (Table 3). To summarize the data, the median progressive-free survival is ranged from 3 to 10 months, and median survival from 7 to 16 months (less than 10 months in the most of the reports); the objective response rate of the tumors was 22%-40%, and 1-year survival was 20%-78% (less than 60% in the most reports). The results in this series are similar to that reported in the above publications. However, in this series, there were 4 cases that had survival of 24 months or more, and their survivals were 24 months in 2 cases and 31 and 37 months in another 2 cases, respectively. At the time of writing the paper, the patient with the longest survival was still alive without evidence of recurrence. There were few patients with long-term survival in the above publications.

Table 3 Treatment of advanced pancreatic carcinoma

In this series there were 13 patients who underwent trans-celiac artery regional chemotherapy. The question is if the chemotherapy is responsible for the longer survival of the patients. But most of the patients who underwent chemotherapy had metastases to peri-pancreatic lymph nodes or the liver and their survival was less than 12 months. The patients that underwent chemotherapy had shorter survival compared to the patients who were not given chemotherapy (figure 1) （P <0.005. The results show that the patients with metastases to peri-pancreatic lymph nodes or the liver had poor prognosis, and the chemotherapy will not result in the longer survival of the patients. Whether the pre- or post combination chemotherapy results in further improvement of survival, it needs to be further investigated.

A great attention is paid for the safety of cryosurgery of pancreatic cancer. Korpan [7] conducted an experiment with dogs that received pancreatic cryosurgery with the disc cryoprobe. The cryodestruction area of the pancreatic parenchyma was clearly defined with a sharp demarcation line. Several hours later, the focus exposed to the cryodestruction became aseptic necrosis with thrombus formation. Four weeks later, it could be seen that loose connective tissue with numbers of blood vessels was being developed. After 9-10 weeks tight connective tissue developed, and after 12 weeks, the transformation of the cryozone of the pancreatic parenchyma was completed. None of the animals developed cryosurgery-related mortality and complications. No post-cryosurgery bleeding, pancreatic fistulae or secondary infection were observed. In this series there was no patient who had cryosurgery-related mortality. The main adverse effects observed were abdominal pain, fever and increased amylase levels. There were a few patients who developed acute pancreatitis, which may be hemorrhagic and necrotic type, but none of them had poor outcome. Therefore, the pancreatic cryosurgery seems to be a safer modality. In addition, 125iodine seed implantation may be performed at the same time of cryosurgery, and no persistent adverse effects as seen in chemo-radiotherapy have been observed in such combinational therapy. The combination therapy consisted of cryosurgery and 125iodine seed implantation is a less- or mini-invasive technique.

Korpan[7,15] pointed out that there was almost no known contraindication with the use of cryosurgery for the treatment of pancreatic cancer. For the most of pancreatic cancer, the cryosurgery can be the substitute of conventional surgery. Certainly, more study may be needed. According to our experiences, for unresectable pancreatic cancer, cryosurgery has the following advantages: (a) Cryosurgery performed during laparotomy will be able to shrink the pancreatic cancer considered to be unresectable by conventional surgery, and therefore transforms a palliative procedure to a relatively radical one. (b) The cryosurgery is a less invasive technique, and has a lower rate of complications when compared with conventional resection. (c) The tumor that has been considered to be unresectable may be treated with percutaneous cryosurgery under ultrasound or CT, which is far less invasive than the intra-operative cryosurgery, but has a similar efficacy. (d) During percutaneous cryosurgery, the other modalities, such as 125iodine seed implantation, may be used simultaneously. (e) Immune enhancement or activation may occur after cryosurgery, which is probably due to a quantitative and qualitative change in the surface antigens (component) of tumor cells. That is called “cryoimmunity” [29]. (e) The cryoablated cancerous tissue becomes more susceptible to chemo/radiotherapy [30].

In conclusion, the cryosurgery, due to its far less invasive nature than conventional pancreas resection and its low rate of complications, should be the preferred modality for the treatment of locally advanced pancreatic cancer. 125Iodine seed implantation is able to destroy the residual cancer cells survived cryosurgery. Hence, the combination of both modalities has a complementary effect.

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