Radiofrequency Ablation

Authors: Dr Wa Cheung*
                            Dr James Burnes *

Background:

Surgery is considered as the curative treatment for most malignant and benign tumours. However, several factors, including patient comorbidity or the anatomy of the lesion, may preclude surgery in some patients. Radiofrequency ablation is one of a number of locoregional therapies that can be used to treat such patients.

Radiofrequency ablation uses a high-frequency alternating current via a needle electrode placed within the tissue to induce temperature changes and consequent coagulative necrosis and tissue desiccation.

Although laparoscopic and open approaches can be used, radiofrequency ablation is usually achieved by an interventional radiologist using a percutaneous approach with either ultrasound or CT scanning guidance. Local or general anaesthesia can be used. The percutaneous approach generally permits the procedure to be carried out as a same day or overnight stay procedure.

What are the prerequisites for having radiofrequency ablation done?

The size and location of the lesion is critical for the success of radiofrequency ablation. Therefore, the decision to use radiofrequency ablation is generally best made after multidisciplinary consultation between surgeons, oncologists and interventional radiologists.

CT scan of the affected region is the commonest preliminary imaging test. Ultrasound, MRI and PET scans may also be required.

Haematology testing including haemoglobin, platelet count, prothrombin time, INR and partial prothrombin time should be carried out, as should liver and renal function tests if the procedure is to be carried out under general anaesthesia or the target organ is the liver or kidney.

Bleeding is the major risk in this procedure. Therefore, anticoagulation (heparin, warfarin, clexane, aspirin, anti-platelets) should be stopped, depending on the patient’s circumstances.

History of allergy to any medication and previous cardiac pacemaker insertion is also important. If a pacemaker is in place, the radiologist should be advised and a cardiologist should be consulted before the procedure.

What are the absolute contraindications for radiofrequency ablation?

Coagulopathy with INR > 1.5 and platelet counts < 50,000 per mm³ are absolute contraindications.

What are the relative contraindications for radiofrequency ablation?

• Excessive tumour burden within one organ.
• Metastases involving more than one organ.
• Tumour position close to essential structures, such as bowel, gallbladder, major bile duct, ureter, spinal cord, nerve or major blood vessels.
• Active infection.
• Inability to lie flat on CT table if CT guidance is used.

NOTE: treatment with aspirin is not a contraindication to radiofrequency ablation.

What are the adverse effects of radiofrequency ablation?

• Pain
• Fever
• Severe bleeding requiring treatment by transfusion and/or other interventions
• Infection, including liver abscess <0.2%
• Tumour seeding <1%
• Skin burns under the grounding pads <0.2%
• Injury to adjacent organ or tissue
• Several specific sites have characteristic adverse effects
• For liver ablation – bowel perforation <0.2%, bile duct stricture <0.1%, pneumothorax <0.1%
• For renal tumour ablation – ureteric stricture <2%, urinoma <1%
• For lung tumour ablation – pneumothorax approximately 50%, pneumothorax requiring chest tube approximately 20%, pleural effusion approximately 20%
• For bone tumour ablation – pathological fracture due to weakening of bone, burning of nerve, skin and muscle have been reported, but are uncommon

Are there alternative imaging tests, interventions or surgical procedures to radiofrequency ablation?

Surgery is the first-line treatment for cancer. Radiofrequency ablation is one of the alternative treatments. Other alternative treatments include chemotherapy, transarterial chemoembolisation, microwave ablation, laser ablation and cryoablation. The decision of which treatment to use relies on tumour type, patient comorbidity, physician and site experience, and availability of treatment options.

Useful websites about radiofrequency ablation:

The American College of Radiology together with the Radiological Society of North America has developed consumer information about radiofrequency ablation:
http://www.radiologyinfo.org/en/sitemap/modal-alias.cfm?modal=rf_ablation

*The author has no conflict of interest with this topic.

Page last modified on 30/8/2018.