Local ablation of pancreatic tumors: State of the art and future perspectives

BACKGROUND Currently,the technologies most commonly used to treat locally advanced pancreatic cancer are radiofrequency ablation(RFA),microwave ablation,and irreversible(IRE)or reversible electroporation combined with low doses of chemotherapeutic drugs.AIM To report an overview and updates on ablative techniques in pancreatic cancer.METHODS Several electronic databases were searched.The search covered the years from January 2000 to January 2021.Moreover,the reference lists of the found papers were analysed for papers not indexed in the electronic databases.All titles and abstracts were analysed.RESULTS We found 30 studies(14 studies for RFA,3 for microwave therapy,10 for IRE,and 3 for electrochemotherapy),comprising 1047 patients,which were analysed further.Two randomized trials were found for IRE.Percutaneous and laparotomy approaches were performed.In the assessed patients,the median maximal diameter of the lesions was in the range of 2.8 to 4.5 cm.All series included patients unfit for surgical treatment,but Martin et al assessed a subgroup of patients with borderline resectable tumours who underwent resection with margin attenuation with IRE.Most studies administered chemotherapy prior to ablative therapies.However,several studies suggest that the key determinant of improved survival is attributable to ablative treatment alone.Nevertheless,the authors suggested chemotherapy before local therapies for several reasons.This strategy may not only downstage a subgroup of patients to curative-intent surgery but also support to recognize patients with biologically unfavourable tumours who would likely not benefit from ablation treatments.Ablation therapies seem safe based on the 1047 patients assessed in this review.The mortality rate ranged from 1.8%to 2%.However,despite the low mortality,the reported rates of severe post procedural complications ranged from 0%-42%.Most reported complications have been self-limiting and manageable.Median overall survival varied between 6.0 and 33 mo.Regarding the technical success rate,assessed papers reported an estimated rate in the range of 85%to 100%.However,the authors reported early recurrence after treatment.A distinct consideration should be made on whether local treatments induce an immune response in the ablated area.Preclinical and clinical studies have shown that RFA is a promising mechanism for inducing antigen-presenting cell infiltration and enhancing the systemic antitumour T-cell immune response and tumour regression.CONCLUSION In the management of patients with pancreatic cancer,the possibility of a multimodal approach should be considered,and conceptually,the combination of RFA with immunotherapy represents a novel angle of attack against this tumour.