Liver lesions respond to new treatment

Nonsurgical strategies for treating liver lesions show promising results, but minimally invasive therapy has yet to realize its potential in tackling hepatocellular carcinoma. Future treatment for this patient population may involve a combination of interventional techniques, according to speakers at AOCR 2004.

U.S. and Asian interventional radiologists stamped the "could do better" verdict on their own work during a day-long HCC symposium at the congress. Targeted therapy must demonstrate significant improvement in survival rates of patients with inoperable lesions if the interventional approaches are to be considered truly successful.

HCC is the fifth most common cancer worldwide and is noted for its poor prognosis. High HCC rates have long concerned health professionals in Asia, where the disease is linked mainly to hepatitis B and to hepatitis C in Japan. The marked increase in both hepatitis B and C infections in the U.S. over the past few years is triggering concern about a similar escalation of the difficult-to-treat cancer in the West.

Interventional options for treating nonresectable HCC lesions can be classified as regional, such as transarterial embolization (TAE), or local, such as radio-frequency ablation. TAE produces necrosis by blocking blood flow to the tumor and a surrounding portion of the liver, while RFA applies highly targeted heat within the tumor itself.

TAE generally involves injection of an emulsion comprising an anticancer drug and the viscous embolic agent Lipiodol. Inclusion of the chemotherapy agent, however, makes the treatment highly toxic, said Dr. Masahide Takahashi, chief radiologist at Tsukuba Gakuen Hospital in Japan.

Trisacryl gelatin microspheres (embospheres), which have been used in neurointervention and uterine arterial embolization, could provide a safer embolic medium, Takahashi said. Initial results of embosphere TAE in 23 patients with 33 HCC tumors (0.8 to 10 cm) have shown results comparable to the drug-containing therapy.

Most target treatments sessions consisted of injection of one prefilled syringe of the smallest embospheres (40 to 120-micron diameter). Five tumors required a single session with larger sized particles (100 to 300 microns), while a few large HCCs were treated with one or two doses of 500 to 700-micron embospheres.

"I usually use the smallest embospheres because I like to embolize the tumor as deep as possible," Takahashi said.

No patients reported pain or discomfort during the procedure. More than half developed low- to high-grade fever for several days after treatment but had no associated reduction in liver function. Mild to moderate elevation of liver enzyme (five cases) and bilirubin (four cases) occurred only in patients with large masses.

Contrast-enhanced dynamic MR performed two weeks after treatment showed complete embolization (no tumor enhancement) in 29 tumors. Repeat MR follow-up found reenhancement in 10 of these lesions two to nine months later. The four nodules showing incomplete TAE from the start had either presented with extrahepatic supply or were quite large, Takahashi said.

Combining TAE and RFA is another promising option. The use of chemoembolization together with thermal ablation could be particularly helpful in treating large tumors or multiple lesions, said Dr. Hyo Lim, a radiologist at the Samsung Medical Center at Sungkyunkwan University in Seoul.

Interventional radiologists at the Mount Elizabeth Hospital in Singapore are also conducting trials on the combined approach. Mount Elizabeth radiologists use RFA to treat HCC lesions smaller than 3 cm in diameter and TAE followed by RFA for tumors up to 10 cm.

"Prior treatment with chemoembolization alters blood flow to the tumor. This reduces heat loss, increasing the area of ablation," said radiologist Dr. Peter Goh Yu-Tang. "Chemoembolization will also attack parts of the tumor not dealt with by RFA."

TAE is generally used alone for an HCC larger than 10 cm, although members of the interventional team are beginning to debulk these lesions with RFA before embolization.