Background: The aim of this study was to evaluate the influence of in situ ablation and hepatic resection of experimental liver metastases on residual intrahepatic tumour growth and macroscopic peritoneal tumour spread.
Methods: Two colonic carcinomas (CC 531) were implanted into 90 WAG rat livers, one in the right liver lobe (untreated tumour) and one in the left liver lobe (treated tumour) of each rat. The animals were randomized into two test groups and a sham-operated control group. Animals in group 1 received in situ ablation (laser-induced thermotherapy) of the treated tumour. Rats in group 2 were submitted to partial hepatectomy. Untreated tumour volumes were calculated and the incidence of macroscopic peritoneal spread was determined at different times.
Results: After 21 days median (95 per cent confidence interval) volumes of untreated tumours were 507 (282) mm(3) in group 1, 2096 (994) mm(3) in group 2 and 1896 (755) mm(3) in group 3. Compared with values obtained before treatment, growth of the untreated tumours had increased significantly after 4 days in group 2, after 7 days in group 3 and after 10 days in group 1. Macroscopic peritoneal tumour spread was detected in six of 30 animals in group 1 (laser), in 20 of 30 in group 2, and in 24 of 30 in group 3.
Conclusion: Compared with hepatic resection, in situ ablation of experimental liver metastases delays and reduces residual intrahepatic tumour growth and macroscopic peritoneal tumour spread.