1:46 PM Abstract No. 83 - Radiofrequency (RF) ablation of normal liver increases tumor growth of remote subcutaneous tumors in an animal tumor model

Abstract

Purpose To characterize the effect of radiofrequency (RFA) ablation of normal liver on tumor growth of remote tumors. Materials and Methods R3230 breast tumors were subcutaneously implanted into female Fisher rats (n=14). When tumors reached 10mm in diameter, animals were randomized (n=7/arm) to either receive RF to normal liver (21g electrode, 1 cm active tip, standardized to tip temperature of 70°C x 5 min via exploratory laparotomy) or to the control group (sham treatment, with needle placement in liver but no RFA). Tumor growth was measured for 7d after treatment, followed by animal sacrifice and tumor harvest to enable immunohistochemistry for proliferative index calculations (% cells positive for Ki-67 staining). Tumor growth curves before and after treatment were also analyzed. Results While tumors in RFA and sham groups were the same size at the time of treatment (11.0±0.7mm vs. 11.3±0.3mm, p=0.48), a significantly greater tumor growth rate was observed in the RFA group such that tumors were significantly larger at 7d compared to sham-treated animals (17.0±2.1mm vs. 13.2±0.8, p=0.02), representing an increase in tumor size by 34.8±0.1% vs. 13.7±0.1% (p Conclusion Although RF ablation of normal liver is necessary to achieve an ablative margin, it can stimulate the growth of tumors remote from the ablation site and external to the treated organ in at least one animal model. Additional studies are required to confirm these findings in other tumor types and clinical scenarios and to assess whether this potentially deleterious acceleration of tumor growth can be reversed through pharmacologic therapy.