Objective: Percutaneous microwave coagulation was performed with a modified system in animal experiments and in a clinical study to evaluate this technique as a treatment option for liver cancer.
Subjects and methods: As an in vitro study, a microwave electrode was inserted 5-6 cm into separated egg white, homogenate of pig liver, and pig liver, with different power outputs and different lengths of inner conductors. In the animal experiment, the sonographically guided coagulation was performed percutaneously nine times and at laparotomy 43 times on 17 adult dogs. The thermal needles were placed parallel to and 5 mm, 8-12 mm, and 15 mm from the electrode. Clinically, 41 patients with hepatocellular carcinoma and 10 patients with hepatic metastases were treated with a 60-W microwave emission for 240-300 sec.
Results: Microwave coagulation using the modified system at 60 W for 300 sec produced a necrosis volume of 3.7 x 2.6 x 2.6 cm. The coagulated volume was elliptic when the exposed inner conductor of the electrode was 27 mm. The temperature at the periphery was 62.0 +/- 5.8 degrees C. During a mean follow-up period of 23 months, in 41 patients with hepatocellular carcinoma, 79% (46/58) of lesions became smaller, and the intratumoral blood flow disappeared in 89% (47/53). All tumors showed decreased density on unenhanced CT, and 84% (32/38) of tumors showed no enhancement on contrast-enhanced CT. In 21 patients with an elevated alpha-fetoprotein level, the level decreased in all 21 and was normalized in 17. A second biopsy on 19 patients showed complete destruction of tumor in 18. In 10 patients with hepatic metastases, the mean follow-up period was 13 months. Shrinkage of lesions occurred in 84% (21/25), and the blood flow inside the tumor disappeared in 75% (12/16) of lesions. Seventy-three percent (8/11) of the nodules showed no enhancement. A second biopsy on six patients showed complete necrosis in five.
Conclusion: Sonographically guided microwave coagulation performed with this modified system was an effective and safe treatment for liver cancer.