For the treatment of metastases to the liver and the lung, interventional radiologists reported early success with two novel approaches at the Society of Interventional Radiology (SIR) 38th Annual Scientific Meeting, held recently in New Orleans.

Cryoablation of Lung Tumors

For patients with metastatic lung/pleura tumors, cryoablation provided excellent short-term local tumor control in the first results of the ECLIPSE trial, which is the first prospective multicenter study of this intervention.¹

“Cryoablation has potential as a treatment for metastatic cancer and could prolong the lives of patients who have limited options,” said David A. Woodrum, MD, PhD, of the Mayo Clinic in Rochester, Minnesota.

The ECLIPSE trial (Evaluating Cryoablation of Metastatic Lung/Pleura Tumors in Patients—Safety and Efficacy) enrolled 40 patients with pulmonary metastatic lesions (up to five lesions ≤ 3.5 cm) who were not candidates for resection. The primary tumors were mainly colon (40%) and renal cell (23%) cancers. General anesthesia was used in 67% of patients, and conscious sedation in 33%. About 15% of patients received chest tubes.

Promising Results

Cryoablation, performed under computed tomography guidance, was performed on 62 tumors, yielding a disease control rate (responses plus stable disease) of 100% at 3 months and 95% at 6 months (with one local failure). Two patients followed for 12 months are still stable, Dr. Woodrum reported.

“We think these results are very promising,” he said. “Cryoablation offers an opportunity to treat patients with few options, but we acknowledge that longer follow-up is needed.”

Adverse events (with per-procedure rates) included pneumothorax (50%), pleural effusion (21%), chest or back pain (13%), hemorrhage (8%), and cough (6%). Three grade 3 events were reported: noncardiac chest pain, pneumothorax, and arteriovenous fistula thrombosis.

Patients in the study had progressive disease while on chemotherapy, or had recurred after surgical resection, thus making them candidates for this intervention. They discontinued chemotherapy about 2 weeks prior to cryoablation, but could restart chemotherapy later. Dr. Woodrum emphasized that cryoablation is intended for patients who are not candidates for resection. He added that the side effects were mostly minor, and the recovery time was short.

Irreversible Electroporation

Other researchers at the SIR meeting reported encouraging results with irreversible electroporation, a form of tumor ablation that uses microsecond electrical pulses to create permanent holes in the cell membrane.² Strong electric fields applied across a cell can cause irreversible permeabilization of the membrane, leading to a disruption of the balance between the molecules inside and outside the cell. This results in cell death without damaging healthy adjacent tissue, according to Constantinos T. Sofocleous, MD, of Memorial Sloan-Kettering Cancer Center, New York, who presented the results at a press briefing. The study’s first author was Mikhail Silk, MD, also of Memorial Sloan-Kettering.

Irreversible electroporation is nonthermal and results in little scar tissue. It is structurally protein-sparing (ie, it allows for the healing of nerves and bile ducts in the area of ablation). Moreover, there is no “heat sink” effect (ie, the electric pulses are not affected by blood flow), and this limits the potential for recurrences for treated tumors located near blood vessels. And the mechanism of cellular killing avoids damage to the extracellular matrix, Dr. Sofocleous said.

“Unlike thermal ablation, [irreversible electroporation] can be performed in close proximity to bile ducts, major vessels, bladder, rectum, and nerves, with an acceptable safety profile. [The technique] may be especially beneficial in treating liver, lung, and pancreatic lesions, as well as lesions that are close to sensitive structures,” he said.

The procedure involves the placement of at least two parallel electrodes, spaced 1.5 to 2 cm apart, through which the energy is delivered. According to Dr. Sofocleous, while the technique is technically challenging, it is far less morbid than traditional surgery and thermal ablation.

Study Details

The study involved 28 patients with 65 metastatic lesions to the liver, soft tissue, and lung. The primary tumors originated mostly in the colon, although eight different tumor types were included. The mean tumor size was 1.9 cm (range, 1–4 cm). Most patients had exhausted all other treatment options, he said.

The interventional radiologists used irreversible electroporation instead of thermal ablation on these patients due to the location of their lesions, near critical structures that could be negatively affected by surgery or thermal ablation, Dr. Sofocleous explained.

Six months after the procedure, the rate of complete ablation was 92%. One patient has had no evidence of tumor for 778 days, and another patient has had no recurrence for 565 days, he reported. The procedure was safe, with one arrhythmia and one portal vein thrombosis occurring among the 28 patients.

Dr. Sofocleous suggested that the technique might be further enhanced by directing a lethal agent to the reversible zone that surrounds the area of irreversible electroporation, or by delivering chemotherapy or genes through the pores. ■

Disclosure: Drs. Woodrum, Sofocleous, and Silk reported no potential conflicts of interest.

References

1. De Baere T, et al: Evaluating cryoablation of metastatic lung/pleura tumors in patients. Society of Interventional Radiology. Abstract 33. Presented April 14, 2013.

2. Silk M, et al: Safety of irreversible electroporation treatment for metastatic disease in humans. Society of Interventional Radiology. Abstract 29. Presented April 14, 2013.