Cryoablation for Kidney Cancer
Many types of cancer, including kidney, liver, lung and prostate carcinomas, can be
destroyed—ablated—where they exist in the body. The cancerous tissue can be eradicated using cold energy (cryoablation) or heat energy (radiofrequency ablation).
Cryoablation can be performed in two ways: Laparoscopically and percutaneously. In laparoscopic cryoablation, the patient is given general anesthesia in the operating room and incisions are made. Laparoscopic surgery is then performed to mobilize the kidney. Once the tumor of the kidney has been identified, it is measured with ultrasound and a tissue biopsy is taken. The cryotherapy needles are then inserted into the tumor of the kidney and frozen. The tumor is frozen twice during the procedure to ensure it is treated adequately. Then the instruments are removed, and the case is completed. Percutaneous cryablation is done if the tumor is advantageously positioned and is used without any major incisions. Laparoscopic surgery would be performed if the tumor is in a disadvantageous position for the percutaneous surgery and if the tumor is larger than four centimeters (1 3/4 inches) in diameter.
When performed with small probes delivered through the skin, or percutaneously, these methods are the least invasive technologies approved by the U.S. Food and Drug Administration to treat kidney tumors. Many kidney cancer specialists increasingly regard percutaneous cryoablation as a safer, more effective technology.
What is percutaneous cryoablation?
In percutaneous cryoablation, no large incisions are made. Instead, an interventional radiologist inserts a thin, needle-like probe through the skin and into the tumor, using advanced imaging technology for guidance. This technique helps avoid larger incisions that are associated with cryoablation during traditional open surgery or minimally invasive laparoscopic surgery.
How does cryoablation work?
Depending on the tumor’s size, one or more probes are inserted into the tumor. Pressurized gas is pumped to a chamber at the needle’s tip, where it expands then cools, creating an iceball chilled to minus 100 degrees Celsius. The iceball engulfs and destroys the tumor while sparing healthy tissue. Ultrathin sensor needles also are inserted at the tumor’s margins to monitor temperatures and ensure that all the cancerous tissue is destroyed.
How is percutaneous cryoablation performed?
The procedure is best performed by a multispecialty team, including a trained urologist working with an interventional radiologist in a surgical suite equipped with an advanced CT (computed tomographic) scanner or magnetic resonance imaging (MRI) scanner. Although some urologists and interventional radiologists work alone, the best outcomes and lowest complication rates result when both specialists work in tandem.
On the day of surgery, the patient is usually lightly sedated to remain relaxed and calm during the procedure. The use of sedation, rather than general anesthesia, reduces the potential for side effects such as nausea and a sore throat. In addition, there is no need to use a catheter during the procedure to void the bladder.
Once the patient is sedated, a numbing medicine is put on the skin where the ablation probes will be placed and a biopsy is taken of the tumor. The cryoablation probes are then inserted, their precise placement in the tumor determined by the CT or MRI scanner. The freezing process is then started. The patient is generally awake and comfortable throughout the procedure. After the process has been completed, another CT or MRI scan is done. Using intravenous contrast material, the urologist and interventional radiologist can confirm that the tumor has been completely ablated. The entire procedure is usually completed in 45 minutes, and the patient is then transferred to the recovery room.
Because no general anesthesia has been given, the patient usually recovers rapidly and is able to eat a regular diet immediately. Typically, the patient is observed in the hospital overnight and then discharged in the morning if all is well.
Who is a candidate for percutanous cryoablation of renal cancer?
There are a number of important considerations when deciding treatment options for a renal cancer patient, including:
The size and general radiographic appearance of the mass
The age and overall health of the patient
The patient’s kidney function
The number of lesions in or on the kidney
The patient’s preference
Cryoablation is a very promising new approach to kidney cancer. Data gathered from several large medical centers indicates that percutaneous cryoablation has successfully cured kidney cancer in about 95 percent of patients. However, 10-year, follow-up data is not yet available. As such, cryoablation is not usually performed on very young patients. Although there are no strict age criteria, slightly older patients who may have some associated medical problems are generally considered good candidates for kidney cryoablation. The cryoablation procedure is typically associated with very little bleeding, fewer complications and faster recovery.
Percutaneous kidney cryoablation is often a good option for patients with more than one tumor because probes can be placed into the different cancer sites without damage to the rest of the kidney. Patients who have inherited conditions, such as Von Hippel-Lindau disease, often have multiple kidney cancers in one or both kidneys. Occasionally, people who do not have this type of inherited disease also can have more than one kidney cancer within a kidney. Because cryoablation destroys only the cancer and leaves the majority of the kidney intact, it is a good approach for people with more than one cancer in a kidney.
Patients with kidney cancers who have poor kidney function or only one kidney also are good candidates for renal cryoablation since the technique does not require the surgeon to control the blood supply to the kidney. Other techniques such as open and laparoscopic partial nephrectomy require the surgeon to temporarily block the blood supply to the kidney, which may negatively affect kidney function.
Cryoablation is generally not recommended for treatment of tumors larger than four centimeters (1 3/4 inches) in diameter.