Unveiling the Wizards of Ablation: The Impact on The Immune System

• Identify the immunological effects of various ablative therapies, including new techniques such as histotripsy


•      Assess the potential synergy between ablative therapies and immunotherapy in cancer treatment

Ablation is essential in cancer treatment for its precise tumor destruction while preserving the surrounding healthy tissue, making it ideal for patients with inoperable tumors or those ineligible for more invasive surgeries. This includes thermal methods – such as microwave ablation (MWA), radiofrequency ablation (RFA), laser-induced thermotherapy (LITT), cryoablation (CA), and high-intensity focused ultrasound (HIFU) – and non-thermal methods like histotripsy and irreversible electroporation (IRE). These techniques varies from non-invasive (histotripsy and HIFU) to minimally invasive. Recent studies are investigating how these methods impact the immune system and potential to enhance immunotherapy, underscoring the evolving role of ablation in comprehensive cancer care.


Clinical Findings/Procedure Details:

Recent research highlights the abscopal effect with histotripsy in a patient with metastatic colorectal cancer to the liver {1}. Similar effects have been observed with other ablative approaches, including MWA for lung metastasis from renal cancer {2} and advanced non-small cell lung cancer {3}. Historical data from nearly five decades ago suggested potential immune infiltration in prostate cancer following CA {4}, and recent research indicates a strong immune response in renal cell carcinoma treated with CA {5}, supporting the use of adjuvant therapies. It is stil unclear whether histotripsy produces a distinc effect on the immune system due to its non-thermal mechanism. However, many ablative methods have been shown to trigger a robust immune response, suggesting possible synergy with systemic therapies. For instance, RFA combined with systemic chemotherapy demonstrated improved outcomes compared chemotherapy alone {6}. Additionally, combining IRE with anti-PD-1 antibody in pancreatic cancer increased cytotoxic and helper T cells while reducing Treg cells, potentially shifting the tumor from a “cold” to a “hot” phenotype {7}.


Conclusion and/or Teaching Points:

The abscopal effect has been observed with numerous ablative techniques, demonstrating their potential to induce a strong immune response. Combining these ablative approaches with systemic therapies, such as immune checkpoint inhibitors, could synergistically enhance the immune response and lead to better patient outcomes.