Percutaneous IRE feasible and safe for locally advanced pancreatic adenocarcinoma

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The results of a study presented at the Society of Interventional Radiology’s 37th Annual Scientific Meeting in San Francisco, USA, provide hope for individuals with inoperable locally advanced pancreatic cancer (LAPC). Irreversible electroporation has been successful in treating primary and metastatic liver cancer and is now in the first stages of implementation as a treatment for pancreatic cancer. 


The study, which set out to evaluate safety and resection rate in locally advanced pancreatic adenocarcinoma using percutaneous irreversible electroporation (IRE) found that the procedure was feasible and safe.

“We think in another 12 to 15 months we will have a lot more evidence to support the use of IRE for inoperable pancreatic cancer patients,” said Govindarajan Narayanan, chief of vascular and interventional radiology, associate professor of clinical radiology and programme director for the vascular interventional radiology fellowship at the University of Miami’s Miller School of Medicine in Miami, USA.


“If we continue to get good results, this procedure could provide a huge benefit for people who do not have a lot of choice. It could potentially change the rules of how these cases are managed,” he added.

The investigators said that persistent vascular encasement after neoadjuvant therapy for LAPC usually contraindicates resection. Neoadjuvant chemoradiation therapy can convert some patients with borderline or unresectable LAPC to resectability. Intraoperative radiofrequency ablation and microwave have been used in the past, with limited success and a high complication rate. 

Percutaneous IRE using the NanoKnife (AngioDynamics) is more versatile than other ablative modalities due to the lack of heat sink effect and morbidity associated with open surgery. “We reviewed records of eight patients with LAPC referred for IRE. The procedures were all done percutaneously under general anaesthesia using a standard protocol. The primary endpoint was safety. Secondary endpoints included survival and resection rate after procedure,” Narayanan noted.

Results

Between December 2010 and September 2011, eight patients with biopsy-proven pancreatic cancer underwent percutaneous ablation of pancreatic tumours using IRE. Median age was 53 years (range 51–72), median time from diagnosis to IRE was 8.8 months (range 2.4–29.2) and the median tumour size was 2.8cm (range 2.5–6.8). All patients had prior chemotherapy and seven had prior radiation, with a median of two lines of prior therapies (range 1–4). Immediate and 24 hour post-procedure CT with contrast demonstrated patent vasculature in the treatment zone in all patients. Two patients (25%) underwent surgery after IRE after four and five months respectively. Both had margin-negative (R0) resections and one had a pathologic complete response. Both remain disease-free at two and six months after resection, respectively. Among the six remaining patients, two were lost to follow-up; one had progressive disease after three months. One patient had a negative follow-up PET scan and surgery is planned. Two remaining patients are under follow-up to determine resectability. Complications included spontaneous pneumothorax during anesthesia (n=1) and pancreatitis (n=1). Both recovered completely.

“In our initial experience, two out of eight patients with unresectable LAPC achieved a margin negative resection after IRE. One had a pathological complete response. A prospective neoadjuvant trial in LAPC incorporating IRE is planned,” said Narayanan. “Without IRE, these people are essentially left with chemotherapy and radiation therapy. At this point the prognosis for this group is pretty dismal and they have an estimated survival of less than one year. With this procedure, there is the potential to have the tumour peeled off the blood vessels, and follow up treatment to repair the affected area of the pancreas,” he noted.

NanoKnife has received clearance from the US Food and Drug Administration for the surgical ablation of soft tissue.


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