Cryotherapy by FNEC (Freezing Nitrogen Ethanol Composite) is a new-developing cryotherapy technique by Taipei Veterans General Hospital.
Some of the bone tumors such as aggressive benign bone tumors, low-grade malignant bone tumor and bony metastasis are easily cause local recurrence. Even by intensive intralesional tumor removal and radiotherapy, there is still 12% to 50% local recurrence rate. To decrease the risk of post-curettage recurrence, several types of local adjuvant treatments, for instance the use of polymethylmethacrylate, phenol, or liquid nitrogen, have been considered. Since the 1960s, cryotherapy by use of liquid nitrogen as the cryogenic source has been used in adjuvant treatment of some musculoskeletal tumors, including GCT, and showed that it is useful in reducing recurrence but is associated with complications related to the freezing.
The mechanisms of cryoablation-mediated cell death have been studied. In brief, rapid freezing induces intracellular ice crystallization and propagation of ice mediates mechanical stress, which causes damage to cellular organelles. The resulting ice recrystallization is accompanied by slow thawing that mediates further damaging stress. The ultimate goal is to eradicate tumor cells without damage to the adjacent healthy tissues. Directly pouring a cryogenic source such as liquid nitrogen into the surgical bone cavity was first introduced by Marcove. However, this treatment is associated with local complications like fracture in as many as 42% of patients; less commonly, skin necrosis and nerve palsy have been reported. These problems have caused investigators to question the merits of this approach. Complications of liquid nitrogen treatment may be caused directly by spills or overflow of the liquid, or by liquid nitrogen’s profound freezing effect ( 196° C) damaging the adjacent normal tissues. To avoid some of the disadvantages associated with the use of directly pouring liquid nitrogen into a tumor cavity after curettage, we explored the development of a novel cryogenic material, freezing nitrogen ethanol.
The surgical technique was performed under tourniquet control. After exposure of the involved bone tissue, a cortical window the size of the longest longitudinal dimension of the tumor was made. After exposure the tumor, the gross tumor was then removed by hand curettes carefully. After that, followed by high-speed burring to remove the tumor invasive into the peripheral area. To further kill all the possible residual tumor nearby, cryotherapy could be applied. We used a warm water-perfused gauze pad to insulate the normal tissues adjacent to the surgical lesions. The freshly prepared semisolid freezing nitrogen ethanol composite was scooped into the lesion cavity. The exterior surface of the freezing nitrogen ethanol composite preparation may melt faster. The melted freezing nitrogen ethanol composite was removed and additional fresh freezing nitrogen ethanol composite was added to ensure a consistent semisolid status. At least 5 minutes of exposure to freezing nitrogen ethanol composite was ensured for the entire bone cavity. Finally, the freezing nitrogen ethanol composite-treated tissue was thawed for 15 minutes. After thawing, bone defect reconstruction was conducted using bone grafts (artificial bone grafts or allografts) and internal fixation by osteosynthesis was dictated by the nature of the lesions.
There are possible risks and complications associated with the surgery, including:
1. infection requiring antibiotics or surgical debridement.
2. Nerve, vessel injury during tumor resection.
The procedure cost is about 150,000 to 300,000 NTD, prices are subject to change without prior notice, need to pay in accordance with the actual medical expenses.