IMAGE-GUIDED
CRYOABLATION
LIVER METASTASIS
Metastatic Liver Cancer
Treatment through Cryotherapy
Surgical resection is still the treatment of choice for patients with liver tumors. Until quite recently, however, there were few treatment options available for patients presenting with cancer of the liver who were, for one reason or another, not candidates for resection surgery.
The goal of hepatic cryoablation is complete destruction of tumors for curative or palliative reasons as an alternative to resection. Cryosurgery (freezing) is a well-established technology and has been used for the treatment of many benign and malignant conditions. Cryotherapy of the liver is performed by placing one or more cryoprobes into the tumor, then cooling the tips of the probes to well below -100o C., creating an iceball that destroys the tumor. Thermal sensors may also be placed to monitor tissue temperatures during the procedure. Cryotherapy ablation has been used to treat secondary liver cancer through an open surgical or laparoscopic approach since approximately 1990. Using intra-operative ultrasound to guide placement of the cryoablation needles and to monitor iceball formation, physicians have been able to achieve complete ablation of the tumor along with an adequate margin, while minimizing the damage to normal liver tissue.
Percutaneous cryoablation is a very recent addition to the liver cancer treatment armamentarium. In the past, the relatively large size of the cryoprobes prevented safe percutaneous placement. The introduction of very thin 17g (1.5mm) cryoablation needles has removed this obstacle. MRI compatible cryoablation needles and thermal sensors are also available, allowing cryoablative treatment for liver cancer to be performed safely as a minimally-invasive procedure under CT or MRI image guidance by a physician specializing in interventional radiology. The ability to perform the procedure percutaneously may expand the patient population that can receive curative as well as palliative treatment for hepatic malignancies.
Currently, most patients who undergo liver cryotherapy are those whose disease is considered medically or technically inoperable or who refuse surgery. It is generally limited to patients whose lesions are 5cm or smaller, and no more than 4 lesions are usually treated per session. Most studies have included patients with secondary liver involvement from colorectal carcinoma. Cryoablation may be an option for patients with metastatic disease from less common primary sites such as neuroendocrine, small intestine and ovarian tumors.
Although there is currently debate on whether survival is prolonged through liver cryotherapy versus surgical resection, it is well-documented that recovery from minimally invasive procedures is often much easier for the patient. Cryotherapy offers an alternative treatment for patients with unresectable metastatic hepatic malignancies.
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