Author: PQ Wu, MD, PHD
The indications of cancer combined with multiple bone metastasis include the uncontrollable medical pain from bone metastasis, close-to or occurred pathological fractures, and bone metastasized tumors that compress the spinal nerves.

As mentioned in our article- ‘Adjuvant therapy after tumor removal - reduces the recurrence significantly’, since intralesional curettage cannot remove the tumor completely, some of the more active tumors may recur after surgery. Hence, to reduce tumor recurrence, physicians will often arrange four to six weeks of radiotherapy for patients after surgery. Radiotherapy does have the opportunity to help control tumors, but similarly, there are some costs that the patients have to bear, including: 
 
  1. Wound infection, non-healing
  2. Stiff joints
  3. A second malignant tumor may develop many years after
  4. Multiple commutes to and from the hospital
 
Therefore, where feasible, if the orthopedic surgeon gives adjuvant therapy, e.g., cryotherapy, after surgery, the residual tumor can be eliminated, and the need for radiotherapy is reduced
 
Additional reading: Adjuvant therapy after tumor removal - reduces the recurrence significantly
 
However, how do we use liquid nitrogen for cryotherapy during surgery? We have two common methods.  
 
1. Direct Pouring
 

One: Direct Pouring, as the name suggests, pours liquid nitrogen into the bone cavity. This method was invented by Dr. Marcove of Sloan-Kettering Hospital in New York in the 1960s. Pour liquid nitrogen directly into the bone to kill the tumor, just like boiling ice water. The effectiveness is quite good, but the orthopedic surgeon must be quite careful to protect nearby skins before freezing and have considerable experience! Therefore, although the effectiveness of this tumor treatment is quite good, complications could easily occur. Hence, it’s not really popular in the orthopedic community.
 

 
 
II. Liquid Nitrogen Spray System


Liquid nitrogen was loaded into a special spray gun, aimed at the treatment target, and sprayed in the form of gas. Compared to the direct pouring method, the spray system is relatively safe. However, it takes a longer time and has a limited applicable range since the sprays can only freeze smaller areas.
 

Liquid nitrogen spray system produced by Brymill Corporation from the United States

The use of the liquid nitrogen spray system to treat the giant cell tumor at the thigh

 
III. FNEC (Freezing Ethanol Composite)

To improve the shortcomings of the cryotherapy mentioned above, our new cryotherapy technology, FNEC, has been developed. We mix ethanol and liquid nitrogen at a certain ratio to obtain an FNEC of minus 114 degrees Celsius. The FNEC can then be placed in the bone tumor site for cryotherapy with considerable easiness. We are currently working on the application for new medical technologies at the Ministry of Health and Welfare. 

With the cryotherapies mentioned above, we expect a great reduction of tumor recurrence rate and better quality of life to patients!
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