In radiofrequency (RF) ablation, the (+) and (-) charged ions in the tissue are moved back and forth by alternating current , and an average of 80-100 degrees heat is created around the needle which results in tissue death in an area of about 3cm in diameter around the needle. This field may vary depending on the type and number of needles used. Since the radiofrequency produces heat by using electric current, a second electrode is placed on the patient's legs to complete the electrical circuit.
RF ablation is a widely used method in medicine for the treatment of heart rhythm disorders, skin tightening in dermatology, varicose veins, snoring management and pain relief. However, its most popular application is tumor destruction. RF was first used in the treatment of liver tumors in 1990s, and then widely applied in lung, kidney, thyroid and bone tumors.
The special needles placed in the tumor during RF ablation are called "probes". The majority of the probes are straight-shaped and have a "water-cooling" system, which prevents the probe from overheating and carbonization. This cooling system expands the area where the probe can heat, but when a single probe is used, this area cannot generally exceed a diameter of 3 cm. Some RF systems allow the use of multiple probes in which case it may be possible to destroy the tumors above 3cm in diameter.
In the straight-shaped probes, the ablation area is elliptical. However, since tumors are usually spherical, the elliptical ablation area may not be sufficient to cover some tumors. In this case, an umbrella-shaped radiofrequency probe may be used. These probes form an ablation zone close to the sphere.
No matter what probe is used, as with all ablation methods, the purpose of RF ablation is to destroy the tumor and a normal tissue (safety margin) of 0.5-1cm thickness around it. If this can be accomplished, the tumor is completely ablated without the need for surgery. For a successful ablation, it is important to place the RF probe correctly in the tumor. Since a single probe is usually used in RF ablation, this probe should be in the center of the tumor. Otherwise, a part of the tumor can stay alive and grow again from this area (recurrence).
RF ablation is mostly used in liver tumors. It is the standard ablation method especially in hepatocellular carcinoma (HCC) and liver metastases.
RF ablation is also commonly used in lung and bone tumors, besides the liver. In the bone, it has largely replaced surgery especially in the treatment of a benign tumor called osteoid osteoma, which causes severe pain in young people. RF is also one of the most commonly used methods in the treatment of thyroid nodules.
Interventional oncology in cancer management
Prof Saim Yilmaz, MD