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Old 03-28-2007, 10:38 AM
Dross Dross is offline
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Default Cryoablation -- A new treatment option for some kidney tumor patients

Mayo Clinic researchers report that freezing kidney tumors through percutaneous cryoablation shows promise for patients who are not good candidates for surgery. Their early findings showing short-term success in more than 90 percent of selected patients are published in this month's issue of Radiology.

The standard treatment for kidney tumors is surgery, providing a high likelihood of a long-term cure. For some patients, surgery is not an option, and Mayo's urologists and radiologists collaborated to find alternatives for these individuals. If these patients are frail due to age or illness or are not able to have surgery because of other factors, percutaneous cryoablation may be an option.

"This procedure appears to be a good option for some patients," says Thomas Atwell, M.D., Mayo Clinic radiologist and the study's primary investigator. "It makes their hospital stay and recovery time very short and surgical stress is minimal." He cautions that this procedure is not ideal for everyone, noting that it is an option for only a relatively small subset of patients.

Percutaneous ablation uses needles to penetrate the skin and deliver directly to the tumor either high-intensity, tissue-destroying heat through radiofrequency ablation, or freezing cold through cryoablation. Mayo Clinic's radiologists are among the most experienced in the world in performing ablation techniques, and have treated nearly 300 kidney tumors either with radiofrequency ablation or cryoablation. Radiofrequency ablation (RFA) burns away the tumor, while cryoablation freezes it.

Mayo Clinic doctors had previous experience with liver tumor cryoablation when they added kidney tumor cryoablation in 2003. Today's report contains the largest published results for percutaneous cryoablation patients. Mayo researchers report that not only can this technique be an alternative to surgery, but that in some cases, it has benefits over RFA.

Previous experience in percutaneous RFA led the researchers to recognize that it has two important limitations. Tumors larger than 3 centimeters are difficult to treat with RFA, with increased rates of technical failures and tumor recurrence. Also, the area being treated cannot be effectively monitored with computed tomography (CT) or ultrasound. The Mayo study findings show that cryoablation can be used for some larger tumors with simultaneous operation of multiple cryoprobes guided by ultrasound. The ablation margin (the edge of the frozen tissue) can be accurately monitored with CT, to ensure that the total tumor mass is treated.

The researchers reviewed the records of the 23 men and 17 women with kidney cancer treated with percutaneous cryoablation at Mayo Clinic between March 12, 2003, and Aug. 4, 2005. They found that this treatment was chosen over RFA for reasons such as larger tumor size, proximity of tumor to ureter or bowel, or a central location on the kidney. Cryoablation was successful in 38 of the 40 patients, with no repeat treatment necessary.

In percutaneous cryoablation, one or more hollow needles are inserted through the skin directly into a tumor. Doctors can observe and guide the insertion by combined use of ultrasound and CT. The needle, or cryoprobe, is filled with argon gas, which results in rapid freezing of the tissue to temperatures of -100° C; and the tissue is then thawed by replacing the argon with helium. The procedure consists of two freezing and thawing cycles, seeking a frozen margin of approximately 5 millimeters beyond the tumor edge to ensure death of the entire tumor. After the cryoprobes are removed, small bandages are placed over the skin puncture sites, and the patient spends one night in the hospital before returning home.

Surgeons continue to seek less invasive methods than the traditional radical nephrectomy (removal of cancerous kidney) for the treatment of small tumors, and percutaneous cryoablation is now on the list. With the incidence of kidney cancer steadily increasing over the last 20 years, and the American Cancer Society predicting nearly 52,000 people will be diagnosed this year, with nearly 13,000 dying from it, another option for some patients is good news say the researchers.

"Additional study is still necessary, but we are confident that percutaneous cryoablation will continue to be a good option for some of our patients," says Bradley Leibovich, M.D., study co-author and Mayo Clinic urologist. "We've seen good results in the initial follow-up with these patients, and hope that the long-term results prove this to be a safe alternative for some kidney tumors." While the researchers caution that they need five to 10 years of follow-up to be able to consider this a curative treatment, they are optimistic about future findings.

Last edited by gdpawel : 11-16-2011 at 03:54 PM. Reason: post full article
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Old 04-22-2011, 12:15 PM
gdpawel gdpawel is offline
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Default Early Success With Laser That Destroys Tumors With Heat

That was three years ago. Now, according to Dr. Eric Walser at the same Mayo Clinic, MRI-guided laser ablation, which heats up and destroys tumors, is a much more precise technology than cryoablation. Of course, physicians at Mayo are among the first in the nation to use this new technique.

Physicians at Mayo Clinic’s Florida campus are among the first in the nation to use a technique known as MRI-guided laser ablation to heat up and destroy kidney and liver tumors. So far, five patients have been successfully treated meaning no visible tumors remained after the procedure.
They join their colleagues at Mayo Clinic’s site in Rochester, Minn., who were the first to use laser ablation on patients with recurrent prostate tumors.

Although the treatment techniques are in the development stage, the physicians say the treatment is potentially beneficial against most tumors in the body either primary or metastatic as long as there are only a few in an organ and they are each less than 5 centimeters in size (about 2 inches in diameter). Patients also cannot have a pacemaker or certain metallic implants, since the procedure is done inside an MRI machine.

“Laser ablation offers us a way to precisely target and kill tumors without harming the rest of an organ. We believe there are a lot of potential uses of this technique which is quite exciting,” says Eric Walser, M.D., an interventional radiologist who has pioneered the technique at Mayo Clinic, Florida.

In the United States, laser ablation is primarily used to treat brain, spine and prostate tumors, but is cleared by the U.S. Food and Drug Administration (FDA) for any soft tissue tumor. Only a few centers have adapted the technique to tumors outside of the brain.

Dr. Walser has been using laser ablation since June. He learned the technique in Italy, where its use is more common, and he adapted it for patients at Mayo Clinic, Florida, many of whom are on a liver transplant waiting list. The clinic is a large liver transplant center, and a number of patients with cirrhosis have small tumors in their liver. “We treated the tumors to keep them at bay because we could not use chemotherapy in these patients, who are quite ill and are waiting for a new liver,” he says. He also adapted it for use in treating kidney tumors.

The outpatient procedure is performed inside an MRI machine, which can precisely monitor temperature inside tumors. A special nonmetal needle is inserted directly into a tumor, and the laser is turned on to deliver light energy. Physicians can watch the temperature gradient as it rises, and they can see exactly in the organ where the heat is. When the tumor and a bit of tissue that surrounds it (which may harbor cancer cells) is heated to the point of destruction which can be clearly seen on monitors the laser is turned off. In larger tumors, several needles are inserted simultaneously.

Patients are given anesthesia because, during the 2.5-minute procedure they should not move, Dr. Walser says. Post-treatment side effects include some local pain and flulike symptoms as the body reacts to, and absorbs, the destroyed tissue, he says. These side effects usually subside in three days to one week.

Dr. Walser adds that laser ablation is a much more precise technology than similar methods that use probes, such as radiofrequency ablation, which also raises a tumor’s temperature, and cryotherapy, which freezes tumors.

David Woodrum, M.D., Ph.D., from Mayo Clinic, Rochester, has also reported success using the new technique.

At the March meeting of the Society of Interventional Radiology, Dr. Woodrum, presented results from the first known cases of using MRI-guided laser ablation to treat prostate tumors. He said then that the safe completion of four clinical cases using the technique to treat prostate cancer in patients who had failed surgery “demonstrates this technology’s potential.”

Dr. Woodrum has now treated seven patients, including a patient with melanoma whose cancer had spread to his liver.

“MRI-guided ablation may prove to be a promising new treatment for prostate cancer recurrences,” he says. “It tailors treatment modality (imaging) and duration to lesion size and location and provides a less invasive and minimally traumatic alternative for men.”

Mayo is the country’s leader in adapting the use of MRI-guided ablation for tumors outside of the brain, say the physicians, who have been collaborating on expanding use of the technology with Visualase Inc., of Houston. The company received FDA clearance in October 2009 for use of laser ablation. Neither Dr. Walser nor Dr. Woodrum has a financial arrangement with the company or a conflict of interest.

Source: Mayo Clinic
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Old 08-03-2011, 06:33 PM
gdpawel gdpawel is offline
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Default Cryoablation of Kidney Cancer

The "standard" approach to kidney cancers is surgical resection, usually a complete nephrectomy, although partial nephrectomies are sometimes done when sparing renal function is imperative.

Small renal masses have recently been treated by cryoablation (freezing to at least -19.4 °C using liquid nitrogen or argon). In cryoablation, a small freezing probe is insertead through the skin, and its tip is placed into the cancerous tissue using CT and ultrasound guidance.

Retrospective studies suggest an around 95% success rate. Subsequent MRI or CT scans are used to evaluate the ablation, with diminution of the tumor in the cryolesion and lack of contrast enhancement considered a favorable result, and increase of the tumor in the cryolesion or interval growth considered signs of inadequate treatment. A percutaneous biopsy, a standard resection, or retreatment with cryoablation can then occur.

The mechanism leading to tumor destruction is uncertain and may be a combination of direct cytotoxicity and damage to vascular elements leading to ischemic necrosis. The cryoablation studies carried out to date fail to convince that a potentially malignant renal mass has been eradicated.

The uncertain biopsy data before and after ablation, short follow-up, and requirements for lengthy general anesthesia and frequently for laparoscopic surgical intervention, weaken the argument for renal cryoablation as a paradigm shift.

The U.S. Food and Drug Administration approved this treatment for kidney cancer, but research studies still need to measure long-term outcomes to compare cryoablation to other treatments.
Kaouk JH, Aron M, Rewcastle JC, Gill IS. Cryotherapy: clinical end points and their experimental foundations. Urology 2006;68(1 suppl):38–44.[

Paul Russo Renal cryoablation: a new treatment in need of careful clinical investigation Nature Clinical Practice Oncology (2006) 3, 286-287
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