Principle
Radiofrequency ablation is a safe, minimally invasive method for the treatment of tumors of less than three centimeters in diameter. RFA is currently the most widely used tumor ablation technique worldwide. The implantation of fine radio-frequency electrodes into tumor tissue is aided by ultrasound, computed tomography (CT) or magnetic resonance imaging (MRI). The passage of radio waves through the applicator tip causes ions in the tissue to oscillate under the alternating current, thereby increasing temperatures within the cell to beyond 60℃, which results in the destruction of the tumor in that area. These temperatures are not sufficiently high to cause damage to adjacent tissue, such as blood vessels. RFA is less expensive than most other suitable therapies and some RFA procedures are in fact covered by health insurance in Taiwan.

Modern RFA machines enable practitioners to monitor the tip temperature and tissue impedance in order to minimize damage and maximize efficiency by adjusting the output power.
 

Benefits of RFA
Percutaneous RFA provides many of the benefits of traditional surgery. For cancer patients for whom surgery is considered too risky, RFA minimizes bleeding, the use of anesthesia, operating time, pain, and the risk of complications. Most patients are able to leave the hospital within one to three days after surgery.
 

Limits of RFA
The temperatures generated by RFA are not very high and the heat is susceptible to dispersion in a process referred to as the "heat sink effect". Thus, tumors near the vascular side, the trachea, and the renal proximal urine collection system are ill-suited to conventional radiofrequency ablation, due to the increased likelihood of residual tumor recurrence.

Patients with massive ascites, severe liver function abnormalities, coagulation dysfunction, easy bleeding, or liver failure are more prone to postoperative complications. Patients with conducted cholangio-intestinal anastomosis or stents are also susceptible to concurrent liver infection after RFA. Thus, RFA is generally not recommended for these patients unless absolutely necessary.

The application of conductive paste is required in the use of most radio frequency devices. Occasionally, the conductivity sheet temperature increases under the effects of extended treatment, which can cause local burning.

It has yet to be determined whether RFA is harmful to pregnant women or the fetus; therefore, it is not currently recommended for these individuals. Furthermore, RFA is not recommended for patients with implanted devices, such as cardiac pacemakers.
 

When to use

1. RFA is commonly used to treat tumors in the liver, kidney, and lungs. In limited cases, experts have also used RFA to treat tumors in the thyroid and breast.
2. In principle, the number of tumors bears no influence on the effectiveness of RFA treatment, however; the number of the tumors affects the duration of treatment. Thus, RFA is generally not recommended for a large number of tumors and the health insurance in Taiwan covers RFA of no more than three tumors.
3. The size of a tumor largely determines the efficiency of RFA treatment; i.e., larger tumors are more difficult to treat in this manner. Tumors of 3-7 cm require updated techniques, including multiple-electrode radiofrequency ablation, bipolar radiofrequency ablation, and perfusion type radiofrequency ablation.
4. Ultrasound-guided radiofrequency ablation is the most common and most convenient method of treatment. Patients undergo percutaneous punctures, which results in little postoperative pain and no exposure to radiation. Computer tomography can be used in cases where ultrasound is ineffectual; however, this tends to extend the treatment time and costs. In cases where the location or size of the tumor(s) precludes percutaneous treatment, doctors can employ endoscopic therapy or combine RFA with other surgical procedures. However, this results in surgical wounds that require longer recovery time. Overall, percutaneous ablation is the treatment of choice.
5. RFA is not recommended for patients with cardiac pacemakers and patients with coagulation or liver dysfunction.
    

Preoperative considerations of RFA

1. Regular testing of blood, liver and kidney function, and coagulation.
2. Patients who receive the CT-guided procedure may need to undergo transcatheter arterial embolization to facilitate positioning. It is not required for patients who receive the ultrasound-guided procedure.
3. Consent forms.
4. Patients receiving local anesthesia do not have to fast, but they must not eat excessively. Patients undergoing systemic anesthesia must observe fasting for no less than six hours.
    

Intraoperative considerations of RFA

1. Use of local anesthesia, intravenous anesthesia, or general anesthesia as required.
2. Use of ultrasound-guided or CT-guided procedures as needed for treatment.
3. Selection of percutaneous treatment, endoscopic therapy, or conventional surgical treatment.
4. Intraoperative conscious patients in any discomfort should contact healthcare providers.

Postoperative considerations of RFA

1. Patients that undergo percutaneous treatment should lie down or lie on one side for at least six hours to facilitate hemostasis. This is not necessary for patients that undergo endoscopic or conventional surgery.
2. Patients that undergo percutaneous treatment may begin drinking or eating six hours after treatment. They must continue fasting if vomiting ensues and/or they feel discomfort. Patients that undergo endoscopic or conventional surgery should follow the advice of their physician with regard to the intake of food and liquids.
3. It is normal for a portion of the wound to be painful and/or exhibit signs of bleeding. If the pain becomes too severe, a physician or nurse should be contacted for advice.
4. Routine tests of blood and inflammation should be reviewed the following day to check for complications.
5. The gauze covering the percutaneous wound may be removed after 24 hours.
6. Ultrasound is unable to distinguish changes in the tumor after treatment. Thus, computerized tomography or magnetic resonance imaging must be used to track tumor progress. This is generally conducted at the first examination one month after treatment to ensure that any viable tumors are dealt with in a timely manner. Further regular examinations are then conducted every three to four months.
    

Risks and Complications
There are three types of complication common to RFA. The first one is bleeding, which occurs in 0.7% of all cases. This can occur at the treatment site, in the chest, in the organs, or subcutaneous bleeding. The second complication is infection, which occurs in 0.3-1 % of all cases. It can occur at the ablation zone, such as a liver abscess, or infection in the chest or abdomen. The third complication is associated with the ablation site. For example, treatment near the diaphragm, the intestine, or the bile ducts can damage the diaphragm and pleural cavity, the intestine and stomach, or the bile duct, respectively. Complications associated with the location of treatment and overall mortality is approximately one per thousand individuals.​