Tumor ablation is a method of treating cancer that is often used when other cancer treatments are not possible. For example, radiofrequency ablation, which is one type of tumor ablation, can treat tumors that are not eligible for surgery because the patient is too weak for surgery, the tumor is located in an area that is not reachable by surgery, or the tumor is not responding to other treatments.
But in most cases, ablation is not a substitute for other cancer therapies. (The exception is in the liver-some researchers suggest that RFA should be the first line of treatment for liver tumors.) The best option is still to surgically remove all the diseased and surrounding tissue. If that option is available, your doctor will use it. When it is not, ablation can be used as an alternate therapy.
Types of Tumor Ablation
There are two main methods of destroying a tumor: heating or freezing.
The most common method of destroying a tumor with heat is radiofrequency ablation (RFA). With this method, the needle electrode inserted into the tumor produces radio waves. The friction these radio waves cause raises the temperature directly around the needle electrode, heating the area to at least 50 degrees C, which kills the tissue.
Laser ablation is similar to radiofrequency ablation, but instead of a needle electrode, a fiber-optic cable is guided into the tumor. The cable is used to fire a laser into the tumor. This method has proven to be less effective than RFA.
Other methods of killing a tumor with heat are microwave ablation and high-intensity focused ultrasound. Microwave ablation uses the different water content in tumor cells versus healthy cells to target a microwave only on cancerous cells. High-intensity focused ultrasound uses tightly and intensely focused ultrasound beams to heat and destroy the tumor. Both of these methods are less tested than RFA.
In cryotherapy, a needle inserted into the tumor freezes the tissue to below –20 degrees C. This forms an ice ball around the tumor, which, like heat, kills the tissue.
Tumor ablation can also be used in conjunction with other cancer therapies.
Tumor Ablation and Chemotherapy
Typically, tumor ablation is recommended for tumors no larger than 3 to 4 cm in size, and the treatment is less effective in larger tumors. But researchers at Harvard Medical School have found that RFA of larger tumors can make the cancer more responsive to lower doses of chemotherapy. This opens up chemotherapy to patients who could not previously tolerate the side effects.
In addition, RFA can be used to treat tumors that are resistant to chemotherapy. As chemotherapy is delivered via the blood stream, tumors with low blood flow are particularly difficult to treat chemically. RFA can specifically target these tumors.
Tumor Ablation and Radiation Therapy
RFA and other tumor ablation treatments can be used in conjunction with radiation treatments. Your doctor may choose to shrink the tumor with RFA, then sterilize the area around the tumor with radiation. In addition, RFA makes tumors more susceptible to radiation treatment.
Tumor Ablation and Surgery
Some tumors are too large or are located in too precarious a place to be removed surgically. Tumor ablation can be used to kill off portions of the tumor. This causes the tumor to shrink, which may make it a suitable candidate for surgery.
Similarly, tumors can sometimes grow too large while a patient is awaiting an organ transplant. Ablation methods can shrink tumors, keeping the patient eligible for a transplant.