Thermoablation Friend and foe of immunotherapy

Background Evidence from multiple studies have shown the potential of thermal ablative therapies to induce regression of metastases and tumors which are distant from the treated metastases-within the same organ or even in other organs-the so-called abscopal effect. Unfortunately, this effect is most often weak and not always reproducible. Recent developments in systemic therapies showed that immunomodulating drugs are of major interest in patient-tailored tumor therapy due to the fact that they are able to enhance the treatment effect of conventional chemotherapy. Furthermore, several studies and reports showed that these immunomodulating therapies are also able to enhance the response of the immune system to the tumor-if combined with local ablative therapies-and trigger a systemic antitumor response. Unfortunately, there is also evidence that effects caused by thermal ablation can hamper the immune system and, therefore, increase tumor growth and tumor spread. Objectives In this article, the effects of thermal ablation in general are described, different (thermo-)ablative techniques are presented and a perspective of combination therapies is given.