ROME — Radiofrequency ablation has largely replaced ethanol injection for percutaneous ablation of primary liver cancer, Dr. Mario Bezzi said at the annual meeting of the Cardiovascular and Radiological Interventional Society of Europe.
Ethanol injection was the standard percutaneous ablative technique from the mid-1980s until quite recently, when three randomized trials from Asia and one from Europe demonstrated the superiority of radiofrequency ablation (RFA), explained Dr. Bezzi, professor of radiology at the University of Rome.
The most persuasive of these studies was conducted at the University of Tokyo. It included 232 randomized patients with primary hepatocellular carcinoma. Four-year survival was 74% in the RFA arm and 57% with ethanol injection. The RFA group was 43% less likely to develop a tumor recurrence and 88% less likely to experience local tumor progression.
The number of treatment sessions needed to achieve tumor ablation in the RFA group was only one-third the number in the ethanol injection group. Mean length of hospitalization was proportionately shorter as well (Gastroenterology 2005;129:122–30).
The explanation for the lesser efficacy of ethanol injection lies in the fact that the alcohol remains confined within the tumor capsule, leaving untreated the small tumor satellites frequently present up to 10 mm beyond the tumor margin.
The price to be paid for RFA's greater efficacy is a slightly higher complication rate, as consistently shown in the randomized trials. Periprocedural mortality in numerous published series is less than 1 in 1,000, the radiologist continued.
Percutaneous ethanol injection remains the preferred approach in liver cancers less than 1 cm in diameter, and for tumors located adjacent to bowel or other critical structures.
Hepatic cancer is the No. 3 cause of cancer mortality worldwide. For now, percutaneous ablation is an option reserved for the roughly 80% of liver cancer patients who are not surgical candidates for various reasons.
The long-term survival of surgery-eligible patients who undergo RFA as a far less invasive alternative is the subject of ongoing randomized trials. It's too early to draw conclusions in this regard.
However, the sole randomized trial that has reported results showed comparable 4-year survival for surgery and percutaneous ethanol injection, Dr. Bezzi noted.
This trial included 161 patients at Sun Yat-Sen University, Guangzhou, China, with a solitary operable hepatocellular carcinoma tumor 5 cm or less in diameter. Four-year survival of 68% was reported in the percutaneous ablation arm and 64% in the surgical group (Ann. Surg. 2006; 243:321–8).
Dr. Bezzi noted that he has reviewed the rapidly growing world literature on RFA for liver cancer, and it's readily apparent that, contrary to manufacturer claims, many different electrode types perform well in treating these malignancies. Moreover, percutaneous ablation is not solely the province of interventional radiologists; comparable success rates are being published by gastroenterologists and surgeons.
Needle tract seeding after RFA of hepatic tumors is an important emerging issue, Dr. Bezzi noted.
“It causes a rapid change in disease stage from stage A to stage C. This is something you don't want. You attempt a curative act and end up with a worse stage of disease.” he said.
He noted that University of Toronto investigators recently reported a 2.7% incidence of neoplastic needle tract seeding confirmed by imaging or surgery in a series of 299 RFA-treated hepatic lesions in 200 patients. Treatment of a subcapsular lesion increased the risk 11.6-fold; the other risk factors were multiple electrode placements or treatment sessions (J. Vasc. Interv. Radiol. 2005;16:485–91).
Ethanol injection leaves untreated the small tumor satellites often present up to 10 mm beyond the tumor margin. DR. BEZZI