Radio-frequency ablation of tumors is going one step higher. Liver RFA -- usually confined to lesions 4 cm and smaller -- also works in large tumors with the aid of a special algorithm that does a better job of calculating probe placement, according to researchers in China.
Dr. Min-Hua Chen and colleagues enrolled in their study 110 patients, 69 with hepatocellular carcinomas and 41 with metastatic liver carcinomas, who were monitored for up to 26 months (mean, 11.4 months) after ablation. Their interventional protocol procured successful ablations and a low rate of recurrence.
The researchers published their findings in the July issue of Radiology.
They ablated 121 tumors ranging in size from 3.6 to 7 cm, performing a total of 536 electrode placements. The procedure's success and local recurrence rates were 87.6% and 24%, respectively. Patients' mean recurrence-free survival was 17.1 months.
Specialists rely mostly on their individual experience to determine the number and mode of ablations required to fry large tumors, which doesn't guarantee a successful procedure. Chen's protocol was based on both mathematic models and clinical expertise and designed to treat lesions larger than 3.5 cm. It determined the number of ablations, optimal mode to overlap them, and best probe placement to ablate large lesions, investigators said.
The technique validates previous reports that weighed the importance of calculating thermal injury target size to develop effective tumor ablation strategies (Dodd et al, AJR 2001; [177]: 777-782).
"It is very important to design an optimal overlapping mode of multiple ablations in RF treatment. Otherwise, there will be residual tumor after the ablation," the investigators said.
The protocol is not infallible. Accurate placement of probes is not always easy, and it requires a skilled specialist. Factors such as an abundant blood supply, undesirable location, tumor texture, and proximity of other organs and structures can contribute to a tumor ablation's failure.
Researchers blame failure in treating large tumors on the inability to determine the optimal number of ablations and the exact location of electrode placement. The suggested mathematical protocol may bring clinical benefits in addressing these problems, the study said.
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