Radiofrequency ablation is a widely used technique as an alternate minimal invasive treatment for non-surgical patients with liver metastases. Post-radiotherapy immune response has been widely studies in preclinical models and patients. It has been shown that RFA strongly modulates the immune system and increase systemic anti-tumor response, leading to “tumor re-challenge resistance” and subsequent immune modulated suppression on more distant hepatic metastasis lesions, known as the referral zone (RZ) phenomenon. It has also been demonstrated that the area surrounding the treated tumor, transitional zone (TZ), might not benefit from this systemic immune effect due to decreased vascular supply (hypoxia). Our overarching goal in this study is to establish if RFA of a single hepatic malignant lesion will focus the systemic immune response upon more distant metastatic lesions with resultant inflammatory anti-tumor effect as measured by increased uptake on the In-111 labeled leukocytes (tagged WBC) scan and change in intensity on FDG PET/CT using pre and post RFA ablation FDG PET/CT and radiolabeled WBC SPECT/CT.
20 patients with biopsy proven metastatic liver disease (more than 2 lesions) with concurrent positive FDG PET/CT who are candidates for RFA and who are naïve to liver radiotherapy will undergo tagged WBC scan before RFA procedure and tagged WBC with FDG PET/CT after RFA procedure. Uptake will be correlated to Tagged WBC and FDG PET/CT imaging, and validated to truth by WBC serum profile, histologic, and immunohistochemistry proof. Results of this pilot study may be used to design larger and more comprehensive studies examining this phenomenon.
Funding: Division of Nuclear Medicine and Molecular Imaging, Department of Radiology and Imaging Sciences
Grant Type: Internal
PI: Bital Savir-Baruch, MD
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