Cryotherapy, or cryoablation, has shown success in treating some cancers.
A small tube or needle pump an extremely cold gas into tumors to freeze the tissue.
Although generally effective at stopping tumor growth, cryotherapy is not a cure.
Ongoing studies are underway to improve cryotherapy techniques.
Cryotherapy is any use of cold temperatures for the treatment of illness. The use of extreme cold to destroy cancerous tissue (cryoablation) has shown success for a small group of cancers, including for malignant pleural mesothelioma.
What is Cryotherapy?
Using the power of cold temperatures to treat illness is not new. In fact, the ancient Egyptians used cold to treat wounds and inflammation as early as 2500 BCE.
But the modern originator of cryotherapy was the British surgeon James Arnott (1797-1883). He used a salt and ice mixture to treat breast, skin, and cervical cancers. His work proved that extreme cold could both reduce the pain caused by the cancer tumors and cause them to shrink.
A physician named Cooper worked with an engineer to develop the first cryoprobe. This multi-layered tube allowed liquid nitrogen to flow through the center tube. It then became a gas at the tip, thus freezing the surrounding area. The probes used today are newer designs of the probe Cooper invented.
Freezing the tumor kills the cancer by damaging it at the cellular level. It is important for the ice ball to be at a minimum 5mm larger than the circumference of the tumor to ensure all of the cancer has been frozen at the desired minimum temperature. After freezing the tissue, it’s allowed to thaw and then it is refrozen. This cycle happens at least twice during the procedure.
The most common types of cancer treated with cryoablation are skin cancers, prostate cancer, some types of breast cancer, and liver cancers. Mesothelioma has also been treated using cryotherapy.
How does cryotherapy treat mesothelioma?
Originally, researchers believed that heat would destroy cancerous mesothelioma cells. A University of California, Los Angeles (UCLA) researcher, Robert Cameron, tested that conclusion with cells in a petri dish. His research concluded that mesothelioma was relatively unaffected by the high temperatures suggested. In fact, he even increased the temperature and the time exposed to over an hour and the cancer cells still didn’t die at a significant rate.
Changing tactics, researchers decided to try cold temperatures instead. A single treatment of 5 minutes in a freezer had the ability to kill almost all of the mesothelioma cells. Researchers continue to build on this study to develop new ways to use cryotherapy in treating mesothelioma. Here are the two most common methods in use.
Cryotherapy using Cryoprobes
Cryoprobes can be very effective in the treatment of pleural mesothelioma. Some of the best results have come as the result of a recent study performed by the Thoracic Surgery Division at the UCLA.
In that study, surgeons treated 24 patients with a total of 107 lesions. They followed the standard procedure as described above, with very successful results: of the 107 tumors treated, 102 never regrew. This means that the patients saw a 95% success rate. Because cryoablation is safe and relatively non-invasive, all procedures were performed on an outpatient basis.
It is important to note that cryotherapy is not curative. These patients were not “healed” of mesothelioma. The cryotherapy treated the tumors that were growing; it did not put the mesothelioma into remission, even if it does slow growth.
In situations like this, cryotherapy is considered a palliative (treating symptoms) or adjuvant (secondary) therapy, and it is frequently performed after lung surgery.
Cryotherapy using CryoSpray
After recognizing that mesothelioma cells are sensitive to cold, researchers began experimenting with other ways to freeze cells at earlier stages to prevent cancer growth.
For instance, according to the 2013 presentation of the Pacific Heart, Lung, and Blood Institute, surgeons and bioengineers are developing ways to spray down large areas of the mesothelium (the dual lining around the lungs) with liquid nitrogen while performing lung-sparing tumor removal surgeries.
Previously, surgeons would remove the diseased lung in its entirety. They later experimented with only removing the tumors and the surrounding tissue, thus saving the lungs. While this later development increased life expectancy and quality of life for the patient, it was unable to remove all of the diseased cells.
But after the UCLA study proved extreme cold was able to destroy mesothelioma cells, researchers began considering freezing larger portions of the tissue when surgically removing tumors. The freezing would be less extensive (only 1mm deep), and the temperature would be relatively warmer (-35C), but the research makes them believe it should be able to kill cancer cells before they are able to form tumors.
The Benefits and Risks of Cryotherapy
As with any form of mesothelioma treatment, cryotherapy has its advantages and disadvantages. Here are some of the benefits and risks associated with cryotherapy for mesothelioma.
Cryoablation is a relatively safe and effective treatment. The major benefits:
Real-time monitoring: Unlike microwave or radiofrequency ablation (i.e., radiation treatment), the size of the therapeutic area (the destructive ice ball) can be seen as it grows through common radiography methods like CT or ultrasound.
Less painful: Because cold induces numbness, cryotherapy is often less painful than other forms of cancer treatment. While the patient commonly describes some mild discomfort as the procedure begins, the surrounding nerves are soon numbed through the cold and the discomfort disappears.
Repeatable: Because the procedure does not involve invasive surgery or harmful radiation, if the tumor regrows, cryoablation can be performed again.
While generally safe, all procedures have their own risks. Surgeons have identified these risks with cryoablation:
Damage to surrounding tissue: To keep nearby healthy cells from being damaged by the cold, surgeons will use hydrodissection – a technique that uses a small amount of water to separate tissue – to prevent unintended organ damage. Skin will be protected from freezing by a warm water pack.
Damage to blood vessels: Freezing minor blood vessels within the ice ball can result in bleeding. Large blood vessels are generally protected from freezing by the warm blood that is still pumping through them.
Important Mesothelioma Cryotherapy Clinical Studies
The following studies have been published, showing the positive results for cryotherapy used to treat mesothelioma.
2009: Titus Regional Medical Center and Franklin Square Hospital. This was an initial safety and feasibility study to ascertain whether spray cryotherapy could be used in the pleural cavity on active tumors. Surgeons sprayed cryotherapy on the tumors for two patients. All tumors receiving the therapy shrunk by over 50%.
2010: David Geffen School of Medicine and UCLA. This was a retrospective record review of 15 patients with localized malignant mesothelioma who had received cryoablation. In all, 30 tumors were treated with a positive response (i.e., tumor shrinkage) in 20, no change in 5, and progression in 5.
2013: Retrospective review of 17 patients who had been treated a combined 75 outpatient cryoablations. After 6mos, 90.7% of all tumors treated showed no sign of recurrence.
Trial in process: Mayo Clinic. The Mayo Clinic is hoping to get 15 patients with MPM enrolled in this study. They will treat mesothelioma tumors with a cryospray. The study is testing how the body’s immune system responds to the treatment. They expect this particular method will induce an anti-tumor immune response. They will be measuring the level of immune cells that infiltrate the tumor post-procedure. As of the time of this article, only one patient has been treated.
Note that these dates above are the dates that the studies were published, not the year the studies took place. Many studies take several years (or longer) to complete.