The effects of hepatic cryosurgery on tumor growth in the liver.

BACKGROUND

The effects of hepatic cryosurgery on residual hepatic tumor growth, and on tumor immunity, have not been determined.

MATERIALS AND METHODS

Two experiments were performed. In both, animals (n = 10 per group) had solitary left lobe hepatomas established, and underwent left lobectomy, cryoablation, or control laparotomy. Experiment I: immediately after tumor treatment, intraportal challenge of hepatoma cells was performed to evaluate for the effects of treatment on residual hepatic tumor growth. Experiment II: animals were challenged 14 days after tumor treatment, and splenocyte cytotoxicity assays were performed to evaluate for tumor immunity. Hepatic tumor nodules were counted 3 weeks after challenge in both experiments.

RESULTS

In animals challenged immediately after tumor treatment, the mean number of liver nodules at 3 weeks was similar between control and cryoablation groups (65 +/- 13 vs 115 +/- 38, P = 0.17). Animals that had undergone resection, however, had a significant increase in the mean number of nodules as compared to cryoablation (278 +/- 74 vs 115 +/- 38, P = 0. 04) and control (278 +/- 74 vs 65 +/- 13, P = 0.002) animals. In addition, only resection animals had elevation in serum levels of the growth factor FGF-basic, 48 h after treatment (mean = 30 +/- 14 pg/ml). In animals challenged 14 days following treatment, all groups had similar numbers of nodules (resection vs cryoablation, P = 0.8). Splenocyte cytotoxicity was not increased after cryosurgical treatment.

CONCLUSIONS

Unlike partial hepatectomy, cryoablation of hepatomas in rats does not accelerate residual tumor growth in the liver or result in production of the growth factor FGF-basic. We did not find evidence for the development of tumor immunity following cryosurgery.