Tumor abolition and antitumor immunostimulation by physico-chemical tumor ablation

Tumor ablation by thermal, chemical and radiological sources has received substantial attention for the treatment of many localized malignancies. The primary goal of most ablation procedures is to eradicate all viable malignant cells within a designated target volume through the application of energy or chemicals. Methods such as radiotherapy, chemical and biological ablation, photodynamic therapy, cryoablation, high-temperature ablation (radiofrequency, microwave, laser, and ultrasound), and electric-based ablation have been developed for focal malignancies. In recent years a large volume of data emerged on the effect of in situ tumor destruction (ablation) on inflammatory and immune components resulting in systemic anti-tumor reactions. It is evident that in situ tumor ablation can involve tumor antigen release, cross presentation and the release of DAMPS and make the tumor its own cellular vaccine. Tumor tissue destruction by in situ ablation may stimulate antigen-specific cellular immunity engendered by an inflammatory milieu. Dendritic cells (DCs) attracted to this microenvironment, will undergo maturation after internalizing cellular debris containing tumor antigens and will be exposed to damage associated molecular pattern (DAMP). Mature DCs can mediate antigen-specific cellular immunity via presentation of processed antigens to T cells. The immunomodulatory properties, exhibited by in situ ablation could portend a future collaboration with immunotherapeutic measures. In this review are summarized and discuss the preclinical and clinical studies pertinent to the phenomena of stimulation of specific anti-tumor immunity by various ablation modalities and the immunology related measures used to boost this response.