Impact of Margin-accentuation IRE in Pancreatic Cancer

Pancreatic cancer is the fourth leading cause of cancer deaths overall and second after colon and rectum cancer among gastrointestinal cancers in Western countries. In Switzerland, 1,172 new pancreatic cancer patients were diagnosed in 2012. Unfortunately, only about 20% of pancreatic cancer patients present at a disease state that allows surgical resection while 30% have locally advanced, unresectable disease and 50% show distant metastases. While the latter two are currently treated in a palliative setting with median survival of at most 6-12 months, patients who undergo tumor resection with curative intentions also achieve only 5-year survival rates of 20-25% in best hands. The reasons for this poor outcome are thought to be chemoresistance, early establishment of metastatic disease, and importantly, high rates of R1 resections. Up to 80% of pancreatic resections have positive resection margins which are often found within the vascular groove and/or at the retroperitoneal margin, close to the superior mesenteric artery. This high rate of positive margins is only found after meticulous pathological work-up and is normally not detected after standard assessment of the specimen. However, the clinical importance of the high positivity of resection margin is even more highlighted as patients undergoing portal vein resection despite negativity of portal vein invasion after regular pathological work-up show significantly better survival compared to patients without portal vein resection. In sum, given the overall poor prognosis despite tumor resection, auxiliary treatment strategies to improve long-term outcomes are desperately needed. Over the last 5 years, irreversible electroporation (IRE) emerged as a non-thermal ablative modality that allows local tumor destruction with sparing vital structures like arteries, venous vessels, as well as the bile and pancreatic duct. There is increasing evidence that IRE for locally unresectable pancreatic cancer is effective with an increase in local progression free survival , distant progression free survival and overall survival compared to historic controls.Data on margin accentuation IRE are sparse while in a recent study published by Martin et al showed that margin accentuation among patients with borderline resectable disease can be performed safe and efficacious if the treatment can be performed "with a high degree of technical ability and skill set".