|Tumor Targeted Cryoablation|
|Tumor Targeted Cryoablation|
Cryoablation also called cryosurgery or tumor targeted cryoablation therapy, is a minimally invasive surgery treatment that uses extreme cold to destroy, or ablate, diseased tissue, including cancer cells. Cryoablation was approved by the U.S. Food and Drug Administration (FDA) in 1999.
The common application of cryoablation is to ablate solid tumors found in the lung, liver, breast, kidney, prostate gland, skin, and soft tissue. In the United States, the most common application is to ablate prostate cancer. But in China, the most common application is to ablate lung, liver, and kidney cancer, and the clinical application has been in progress for more than 9 years. More than 30,000 cancer patients have received the treatment in China. Medical practices have proven that cyoablation is a safe, highly effective therapy with minimal pain and side effects.
PrinciplesThe System controls up to 8 CryoProbes to deliver cold temperature to the targeted tissue and 8
independent TempProbes to monitor temperature in the surrounding tissue. Each cryoprobe incorporates a thermocouple to measure temperature at the probe tip and its signal is used to monitor and control some operations of the system.
Cryoprobes operate on the Joule-Thompson Principle and utilize inert Argon and Helium gases at room temperature as cooling or heating agents. It freezes very fast. The tissues can be frozen to below -100℃ within 30 seconds. Also the freezing capacity is focused (targeted) and limited to the distal tip of the probes to destroy cancerous tissues while sparing normal tissues. Both are distinctive advantages over any other cryo-medical devices. It is the only device that can be used for percutaneous applications.
How does the procedure work?Cryotherapy applies nitrogen or argon gas at extremely cold temperatures to destroy diseased tissue. To destroy diseased tissue located outside the body, liquid nitrogen is applied directly with a cotton swab or spray device. For internal tumors, the physician will use image-guidance to insert a cryoprobe or a series of small needles through the skin to the site of the diseased tissue and then deliver liquid nitrogen or argon gas.
Living tissue, healthy or diseased, cannot withstand extremely cold conditions and will die from:
Fast freezing grows ice crystals inside and outside the cells rapidly and fast thawing by helium gas cracks the lethal ice quickly. The cell mitochondria disappear, the membranes are split, nucleases are broken or dissolved, all resulting in cell death. Cryoablation causes cell structure damage and cell membrane obstruction. It also causes an imbalance of electrolytes and osmosis pressure in and out of the cell. In this way, cancerous cells are destroyed.
Embolism Effects on Blood Vessels
Cryoablation allows for rapid freezing/thawing exchanges in the targeted zone to cause dehydration of micro blood vessels, protein denaturation, interior membrane damage of these vessels, and ischemia. It gathers platelets in targeted zones, causes blood vessel congestion, and shrinking and deformation of cells.
Cryoablation causes cracking and necrosis of tumor cells and forces the decline of tumor markers like CEA, AFP and PSA. It can regulate and control tumor antigens, boost lymph cell hyperplasia, increase secretion of IL-2, IL-6, apoptosis factors and anti-cancer antibodies, and improve the patients’ immunity.
Image-guided procedures such as cryotherapy are most often performed by a specially trained interventional radiologist in an interventional radiology suite or operating room.
This procedure is often done on an outpatient basis. You will be positioned on the examining table. To destroy diseased tissue located outside the body, your physician will apply liquid nitrogen to the area with a cotton swab or spray device.
For internal tumors, your physician will perform a percutaneous procedure, which involves inserting small, hollow, needles through the skin.
You will be connected to monitors that track your heart rate, blood pressure, and pulse during the procedure. A nurse or technologist will insert an intravenous (IV) line into a vein in your hand or arm so that sedative medication can be given intravenously. You may also receive general anesthesia.
The area where the electrodes or cryoprobe are to be inserted will be shaved, sterilized, and covered with a surgical drape.
A very small nick is made in the skin at the site. Using image-guidance, the physician will insert the cryoprobe or a series of small needles through the skin to the site of the diseased tissue. Once the needles or cryoprobe(s) are in place, the liquid nitrogen or argon gas is delivered.
For prostate cancer, six to eight needle probes are inserted through the perineum (the tissue between the rectum and the scrotum and penis) using ultrasound guidance.
At the end of the procedure, the needles or cryoprobe(s) are removed and pressure will be applied to stop any bleeding. The opening in the skin is covered with a bandage. No sutures are needed.
Your intravenous line will be removed.
The entire procedure is usually completed within one to two hours.
Highly visible under image guidance
Cryoablation can be guided by ultrasound (US), CT, X-ray, and DSA. Good intraoperative image monitoring ensures accurate control of ablation zones.
In CT imaging, the ice ball produces a 40 Hounsfield unit drop in attenuation which is shown as a low-density shadow. CT allows for complete visual monitoring and verification of the ice ablation zone.
In US imaging, the ice ball is clearly visible. The ice is in the low echo field (dark) while its periphery is a strong echo field (bright).
Cold is one of nature’s anesthetics. Therefore, cryoablation results in little or no discomfort or pain during the procedure.
When cold temperatures are applied, cryocatheters stick to the tissue they touch, much like a tongue on cold metal. This is an advantage because ablation is performed in a beating heart where there is constant movement. By sticking to the exact spot to be ablated, the electrophysiologist can avoid any accidental slips of the catheter tip, thereby preventing accidental damage to critical structures nearby.
Ability to confirm target ablation site
Cryoablation allows the electrophysiologist to slightly freeze tissue to test whether it is responsible for conducting an arrhythmia. Heat-based therapies don’t allow that – once the tissue is burned, it stays burned. By contrast, cryoablation allows the electrophysiologist to re-warm frozen tissue (that is not responsible for the arrhythmia) and restore its normal electrical function.
Minimizes the risk of damaging critical structures
Treating arrhythmias with ablation involves working very close to critical structures. Damage to critical structures can result in the permanent interruption of normal electrical conduction in the heart and require the placement of an artificial pacemaker in the patient – an outcome everyone absolutely wants to avoid. With cryoablation – which freezes tissue instead of burning it – the risk of damage to these critical structures is minimized.
Minimizes the risk of perforation
Perforation – for example, to the atrial wall – is a dangerous risk that can lead to serious complications. Thanks to its ability to preserve tissue integrity, there is minimal risk of perforation with cryoablation.
No crust formation
Heat burns. Burns can cause a crust to form over the affected tissue, known as a thrombus. The crust may fall off and lodge in a blood vessel, causing a blood clot which can lead to stroke. With cryoablation, this risk is minimized.
Multiple cryoprobes may be used simultaneously
Multiple Cryoprobes used simultaneously can create a large ablation zone and allow treatment of multiple tumors concurrently.
Clinical Study Reference
1. Clinical Study of TACE Combined with CT Guided Percutaneous Targeted Argon-helium Cryoablation to Treat Liver Carcinoma, SONG Qian, LI Lu-Jia, et al., China Journal of Modern Medicine, 2005, 15: 3178-80
3. Treatment of 50 Cases with Advanced Hepatocellular Carcinoma by Combination of TACE with Cryotherapy of Employing Argon/Helium, LIAN Zu-Ping, BAI Guang-De, et al., Modern Oncology, 2006, 14: 1106-08
6. Treatment Efficacy of Argon Super Cyrosurgery System Therapy in Combination with Transcatheter Arteria Chemoembolization for hepatocellular Carcinoma, CHEN Ye, CHEN Mei, et al., Central Plains medical Journal, 2008, 35: 8-9
8. Clinical Analysis of the Therapy for Recurrent and Intractable Non-small Cell Lung Cancer with Combination of Cryoablation and Intervention, ZHANG Fu-tong, LI Xiu-li, et al., J Intervent Radiol, 2007, 16: 759-61
10. Clinical Study of Percutaneous Cryosurgery Combined with Chemotherapy in Treatment for 253 Cases with Advanced Non-small Cell Lung Cancer, FENG Hua-song, NIE Zhou-shan, et al., China Cancer, 2007, 16: 898-901