The Role of Image-Guided Oncology and Local Tumor Treatments

Pech: There are indeed distinct limitations of thermal ablation such as radiofrequency ablation (RFA), despite RFA being the most frequently used local ablation tool available. However, in many cases anatomical locations with adjacent thermosensitive structures or the size of a specific lesion represent strong limitations in daily routine, requiring more efforts in the development of non-thermal ablation techniques. Ultimately, the toolbox enabling minimally traumatic local treatments will be decisive for patient outcome – in a patient selection beyond what is considered suitable for local approaches today. However, even today the combination of thermal ablation, resection, and radiation allows extensive macroscopic tumor cell count reduction in almost all patients considered ‘oligometastatic’. Local tumor ablation may strongly improve the outcome of systemic chemotherapies or targeted treatments. According to the Goldie-Coldman hypothesis from the 1970s (!), extensive local treatment (with reasonable interventional risk) reduces the mathematical probability of a chemotherapy-resistant clonal selection. Hence, local tumor ablation or local treatment in general promotes an optimal environment for simultaneous chemotherapy – it may even help to suppress resistant clones if used in between chemotherapy cycles (in biologically suitable candidates!). In the CELIM study [1], patients resected R0 or ablated completely after downstaging had almost twofold survival rates as compared to R1-resected patients. Maybe there is a selection bias in that study; however, would this result not best be explained by clonal selection pressure through complete resection? Question 2: Local tumor ablation in combination with chemotherapy would undoubtedly result in the best imaginable ‘deepness of response’. If deepness of response truly works, such as proven for colorectal metastases [2], what would you recommend to your patients if the procedural risk is low with minimally invasive ablation?