In Situ Ablation Of Breast Tumors. What Is The State Of The Art?
Article by Michael S. Sabel, MD
Assistant Professor of Surgery
University of Michigan Comprehensive Cancer Center
treatment of breast
cancer through the majority of the twentieth century was the radical
the removal of the entire breast, the overlying skin, the underlying
and all of the lymph nodes underneath the arm. This operation was very
disfiguring, had significant side effects, and while it prevented local
recurrence (the chance of the cancer returning on the chest wall), it
to cure many patients. Since that time, the treatment of breast cancer
has shifted away from mastectomy and towards removing just the cancer,
leaving the normal breast tissue intact. It was discovered that
a lumpectomy (where just the tumor is removed with a margin of normal
with radiation to the breast resulted in a low rate of local
almost as low as with a mastectomy. This led to a very large study in
United States involving nearly 2000 women that demonstrated that a
plus radiation was equivalent to a mastectomy. These results were
by trials around the world, and in 1990 the National Institutes of
recommended that breast-conservation therapy was the appropriate method
of primary surgery for most women with early breast cancer. The
of breast conservation as an alternative to mastectomy has grown
as more women have tumor detected at a smaller size with the increased
use of screening mammography.
Radiofrequency ablation (RFA) delivers an electrical current to the tumor tissues, which causes them to vibrate rapidly and create frictional heating. Using ultrasound, a surgeon can place a probe at the center of a tumor, and then small prongs are deployed around it (like an umbrella). The probe is connected to a generator and the electrical current raises the temperature at the site to 95 degrees Celcius and maintained for about 15 minutes. This is used quite commonly in the treatment of tumors in the liver, and is now being studied in the breast. Several studies are ongoing at the University of Texas MD Anderson Cancer Center, Weill Cornell Breast Center and John Wayne Cancer Institute where women with breast cancer underwent destruction of their tumors by RFA and then had standard surgery. The patients tolerated the procedure very well, with very few side effects. When they looked at the tissue after surgical resection, almost all the tumors had been completely destroyed by RFA. Plans are underway to begin a study at MD Anderson Cancer Center where breast cancers are ablated with RFA followed by radiation therapy without surgical resection.
Lasers can also be used to heat and destroy tumors while still in the breast. A fiberoptic cable can be placed within a tumor using either stereotactic guidance (similar to when a biopsy is performed) or MRI. At the tip of the cable is a diffusing quartz. Light energy from the laser is passed through the cable and the resulting heat can destroy a sphere surrounding tissue around the laser tip. The amount of laser energy needed to be sure to destroy the tumor can be calculated based on size of the tumor, including a 0.5 cm margin of normal breast tissue. The procedure has been performed safely with minimal pain. Like with RFA, after the breast cancers were destroyed by laser, they were surgically resected and examined by a pathologist. Complete destruction of the tumor was shown in a majority of patients, however several patients had breast cancer cells that were still present at the time of surgery. Research is ongoing at Rush-Presbyterian-St. Lukeâââ¬ââ¢s Hospital and the University of Arkansas to improve the ability of laser ablation to destroy 100% of tumors.
ablation or laser therapy, which use heat to destroy tumors,
utilizes freezing temperatures to destroy cancer cells. Cryosurgery has
actually been looked at as a method to treat advanced breast cancers
many years. Likewise, it has been a standard method of treating skin
Advances in technology, specifically the development of a thin probe
can freeze lesions deeper in the body, has paved the way for
to be used to treat cancers in the liver or prostate. It is also be
as a method to treat early stage breast cancers. Using ultrasound
a cryoprobe- essentially a large needle with a tip that gets extremely
cold- is placed into the lesion (see Figure 1).
Using ultrasound guidance, the cryoprobe is placed through a small incision in the skin so that it sits at the center of the breast cancer.
The tip of the cryoprobe gets extremely cold, causing an iceball to form around the cancer. This destroys the cancer, and can be visualized with ultrasound. After freezing the cancer twice, the probe is removed and a Band-Aid is placed over the skin incision.
Typically the tumor is frozen, thawed, and then frozen again before removing the probe. Studies where cryosurgery was performed followed by surgical resection have shown that complete tumor death could be obtained when small tumors were frozen in this method. In addition to the excellent cosmetic results seen with cryosurgery, there is some evidence that freezing tumors can stimulate the immune system to destroy cancer cells elsewhere in the body. If this is true, then cryosurgery may hold benefits beyond destruction of the local tumors. Ongoing studies at The University of Michigan are examining both the feasibility of cryosurgery to completely destroy early stage breast cancers and stimulate an immune response.
Focused Ultrasound and Microwave Thermotherapy:
and cryoablation all require the placement of a probe within the tumor
to achieve their results. Therefore they are referred to as
invasive.âââ¬ÂÂ Newer technologies
investigated for the
of breast cancer that are truly non-invasive. This means that no probe
needs to placed into the center of the tumor, but rather the tumors can
be heated from outside the breast.
tremendous potential as a treatment for early-stage breast cancer.
studies have shown that each of the methods discussed can be performed
safely, with little discomfort to the patient and minimal side effects.
After being destroyed, the dead tissue is absorbed by the body, leaving
a normal appearing breast without a scar. The procedures can usually be
done without intravenous sedation, so many women could potentially be
in the office without the need for a trip to the operating room. This
greatly improve the cost and convenience of breast cancer treatment.
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