Hyperthermic Isolated Limb Perfusion for Melanoma
Hyperthermic isolated limb perfusion is a treatment used for an aggressive form of melanoma that occurs on extremities known as in transit metastases. This form of advanced disease usually presents as multiple nodules that in an area surrounding the site from where the primary melanoma was excised. Often times the lesions are black in color, but occasionally they are not. Their natural history without treatment is to increase in number and size, and the lesions often become ulcerated and foul smelling wounds. The best form of therapy is surgical excision of individual lesions when they are small; however, this approach is feasible when the total number of lesions and their scope is limited (1 - 5 lesions). Once there are more lesions than this, surgery is rarely feasible and rarely indicated because it is highly likely that additional microscopic lesions are present throughout the extremity. In this instance, it is well accepted that the most effective form of therapy is hyperthermic isolated limb perfusion, a treatment approach in which 80% of treated patients experience regression of their tumor nodules, with complete regression (complete disappearance) of the tumor nodules in half of these patients.
Hyperthermic isolated limb perfusion is an operation usually performed under general anesthesia in which the main artery and vein of the affected extremity are connected to a bypass circuit, to completely isolate the blood flow to and from the limb. The bypass circuit uses a heart-lung bypass oxygenator and cardiac bypass pump to control oxygenation, temperature, and flow of the blood in the limb. This perfusion circuitry is operated by a certified cardiopulmonary perfusionist with experience in chemotherapeutic limb perfusion.
By having the affected limb connected to a perfusion circuit and with its blood completely isolated from that of the remainder of the body, it is possible to warm the blood and the extremity to a temperature of 40.5 degrees Centigrade (105 degrees Fahrenheit) without warming the entire body. A very high dose of chemotherapy agent (Melphalan) is administered into the perfusion circuit to expose the extremity to high doses of Melphalan without exposing the entire body to the drug. The combination of heat and high dose Melphalan circulated in the extremity for one hour induces tumor regression in 80% of patients. The operation usually lasts a total of 3 to 4 hours and most patients are discharged on the second day following surgery. Subsequent regression of tumor takes place over 2 - 10 weeks. The procedure of hyperthermic isolated limb perfusion does have some risks and is not indicated in some patients, including those that have significant tumor burden in sights other than the affected extremity. The procedure cannot be used to treat in transit metastases that occur on the thorax or head/neck.