Sequential pathological and immunologic analysis of percutaneous microwave coagulation therapy of hepatocellular carcinoma.

PURPOSE: To evaluate sequential pathologic and immunologic changes and their prognostic significance after percutaneous microwave coagulation therapy (PMCT) of hepatocellular carcinoma (HCC).
METHODS: Eighty-nine nodules in 82 consecutive patients were studied. The 89 nodules were divided into two groups: a treatment group, with 82 primary nodules (average dimension was 3.4 +/- 1.2 cm) in 82 patients, and a control group, of seven nodules (average dimension was 1.4 +/- 0.6 cm) in seven patients. The criteria for a nodule's inclusion in the control group was that the nodule was one of two nodules in the same patient and that the two nodules were located in different liver lobes. This guarantees that while one nodule is treated by PMCT, the distant one will not be directly affected by the microwave thermal field. The control group nodules were treated after the study was completed. Specimens were taken with ultrasound-guided liver biopsy from the treated nodule and the control nodule, pre- and post-PMCT. Infiltration by T-lymphocytes, B-lymphocytes, NK cells and macrophages in the tumour tissue were observed immunohistochemically using a panel of monoclonal antibodies against CD3, CD45RO, CD20, CD56 and CD68. The extent of immune cell infiltration was compared both before and after PMCT, as well as between the treated and control nodules. The relationship between the prognosis and the extent of immunocyte infiltration was analysed.
RESULTS: The patients were followed for 2-26 months (mean 14.6 +/- 6.3) post-treatment. The recurrence rates at 1 and 2 years were 20.4% and 28.1% within the liver in treatment group, respectively. The survival rates at 1 and 2 years were 92.5% and 75.3% for the treatment group. T-cells, NK cells and macrophages increased significantly in both treated and untreated nodules after PMCT, albeit less markedly within untreated nodules when compared to the treated ones. There is a statistically significant correlation between survival outcome and the extent of immunocyte infiltration.
CONCLUSIONS: For inoperable HCC patients, PMCT is one of the treatment choices shown to be effective. Apart from its tissue coagulation effect, an increased systemic immune response directed against the tumour may also play an important role in improved survival.