Reduced Tumor Growth with Combined Radiofrequency Ablation and Radiation Therapy in a Rat Breast Tumor Model

Abstract

Combined RF ablation and external-beam radiation therapy increased animal survival compared with that with either of the treatments alone or with no treatment.

Chemoradionuclide Therapy with186Re-labeled Liposomal Doxorubicin in Combination with Radiofrequency Ablation for Effective Treatment of Head and Neck Cancer in a Nude Rat Tumor Xenograft Model

“…Viable tumor volumes for liposomal doxorubicin plus RF ablation, EXPERIMENTAL STUDIES: Chemoradionuclide Therapy with 186 Re-labeled Liposomal Doxorubicin Soundararajan et al 186 Re-liposomal doxorubicin did not result in a signifi cant decrease in average tumor volume or viable tumor volume compared to that with 186 Re-liposomal doxorubicin alone, four of six rats showed a decreasing tumor volume at 6 weeks. Possible reasons why we did not see complete tumor control as achieved by Horkan et al ( 24 ) with a combination of radiation therapy and RF ablation are as follows: (a) The tumor diameter in our study was twice that reported by Horkan et al (2.05 cm 6 0.24 vs 1.0 cm, respectively); (b) 186 Re radiation dose rate is not constant owing to clearance and decay and, hence, could allow for repair and repopulation of tumor cells; (c) the width of the remaining pepercentage injected dose of FDG could be used to measure therapeutic effi cacy in addition to changes in tumor volume in a preclinical model.…”

“…RF ablation in combination with liposomal doxorubicin increased not only the ablation zone but also the drug accumulation in the tumor periphery, where recurrence occurs ( 19 ). Reduced tumor growth with RF ablation and external beam radiation therapy has also been reported ( 24 ) and attributed to the increased oxygenation in the peripheral tumor owing to hyperthermia, which sensitizes the tumor to radiation therapy. Considering the synergy achieved with RF ablation and chemotherapy or radiation therapy, we investigated the potential of RF ablation and chemoradionuclide therapy.…”

“…It has been diffi cult to achieve complete ablation of large or infi ltrative tumors and those adjacent to large blood vessels ( 18,34 ). New treatment strategies (eg, combination of RF ablation with chemotherapy or antiangiogenic or radiation therapy) have been developed to overcome this limitation ( 19,(22)(23)(24)36 ). RF ablation in combination with liposomal doxorubicin increased not only the ablation zone but also the drug accumulation in the tumor periphery, where recurrence occurs ( 19 ).…”

“…Increased effi cacy could be due to the deposition of high local 186 Re b radiation dose in addition to doxorubicin cytotoxicity. A study of RF ablation combined with 20-Gy external beam radiation ther apy reported that 82% of animals had complete tumor control ( 24 ). Although the addition of RF ablation to ripheral tumor is larger than the path length of the b emission of 186 Re and, hence, the distant cancer cells could not be treated; and (d) tumor vasculature was heterogeneous, leading to a heterogeneous distribution of liposomes in tumor.…”

“…A major drawback of RF ablation is the inability to completely destroy the tumor ( 18 ). To overcome this problem, RF ablation has been used in combination with liposomal doxorubicin (19)(20)(21) and other therapies (22)(23)(24)(25), resulting in larger volumes of tumor destruction.…”