Minimally Invasive Tumor Therapy (MITT)

Department of Radiology, Charité – Universitätsmedizin Berlin

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References

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    Semin Intervent Radiol. 2013 Jun;30(2):141-150. Review
  3. Sharma A, Abtin F, Shepard JA. Image-guided ablative therapies for lung cancer.
    Radiol Clin North Am. 2012 Sep;50(5):975-99. doi: 10.1016/j.rcl.2012.06.004. Review
  4. Crocetti L, Lencioni R. Radiofrequency ablation of pulmonary tumors. Eur J Radiol. 2010 Jul;75(1):23-7. doi: 10.1016/j.ejrad.2010.04.011. Epub 2010 May 10

 

Radiofrequency Ablation (RFA) for the Treatment of Lung Tumors

 

Surgical removal (resection) is the best treatment choice for patients with an isolated lung metastasis or early, locally confined lung cancer. However, many patients are not surgical candidates because they have poor lung function, high surgical risk, or other severe diseases. Traditional treatment options for these patients include radiotherapy and systemic (whole body) chemotherapy.

 

Radiotherapy and chemotherapy have some beneficial effect, but they also tend to have unwanted toxic effects. These side effects are especially dangerous for patients with impaired lung function or other serious health problems.

 

These drawbacks of traditional therapies have led to the development of different types of minimally invasive ablation treatment over the last two decades. The new interventional treatments play an increasing role in the integrated care of cancer patients. In 1995, physicians at Harvard University in America were the first to use minimally invasive radiofrequency ablation (RFA) for the treatment of inoperable lung tumors. RFA treatment of lung tumors has since attracted much attention. Many studies performed in recent years have provided scientific evidence that RFA is a safe and effective treatment option. Today, it is considered a valid alternative treatment for patients with primary and secondary lung tumors that cannot be removed by surgery. .

 

How Does RFA Work?

 

RFA uses heat to destroy cancer cells. The heat is generated within the tumor using a needle-like electrode (RFA probe) with a diameter of about 3 mm. The electrode is advanced through the skin (percutaneously) into the tumor using computed tomography (CT) for guidance. This allows the radiologist to see the electrode inside the patient’s body. Once the electrode has been positioned, the generator is activated to produce the radiofrequency energy necessary to destroy the tumor. The tumor tissue around the electrode tip is heated to a temperature of up to about 100°C. The heat causes cell death and destroys the tumor by a process known as coagulation necrosis (Figure 1).

 

Figure 1: Mechanism of radiofrequency ablation (RFA). A thin needle-like electrode (RFA probe) placed within the tumor (red) is used to deliver a high-frequency alternating current (400 - 500 kHz). This radiofrequency energy causes agitation of charged particles (ions), generating frictional heat around the electrode tip. The heat destroys the tumor cells.

 

Radiofrequency energy is applied for 15 – 30 minutes. At the end of ablation, the electrode is removed, and the tract is sealed with tissue glue. RFA treatment is minimally invasive because it requires no large skin incisions (cuts). Most patients tolerate the procedure very well with local anesthesia and a strong intravenous painkiller. General anesthesia is usually not required. Many small lung tumors can be treated in a single session. We do not use RFA to treat tumors more than 5 cm in size. Patients who develop new lung tumors after their first RFA may be considered for repeat RFA treatment.

 

What are Possible Complications of RFA?

 

The risk of complications with RFA is low. Some possible complications are related to the percutaneous insertion and positioning of the RFA probe. The most common complication of RFA of a lung tumor is the escape of air into the space around the lung, causing a part or all of the lung to collapse (pneumothorax). The air can be drained by inserting a chest tube (also known as a Bülau drain). The drain will be removed after a couple of days. Patients should be aware that they may cough up blood (hemoptysis) for a few days. As with RFA elsewhere in the body, there is a risk of burn or other injuries to nearby organs, including the bronchi, the trachea, the heart, the liver, the diaphragm, the esophagus, and the nerves. However, these complications can usually be avoided because the radiologist uses CT scans to guide the electrode into the right position and to watch the procedure while applying the ablation energy. Some patients may develop an infection with abscess or bleeding at the treatment site.

 

Advantages and Disadvantages of RFA

 

RFA is a safe and effective treatment option with a low complication rate for patients with primary or secondary lung tumors. RFA is well tolerated by most patients because no large incisions are required and the use of image guidance for insertion and positioning of the RFA electrode within the tumor minimizes complications. Therefore, it is a good option for patients who have had lung surgery before or who cannot have repeat surgery due to other health problems.

 

The effectiveness and safety of RFA treatment varies with the size of the tumor and its location within the lung. With the currently available RFA probes, we can effectively treat lung tumors with a size of up to 4 cm, at most 5 cm. The effectiveness of heat treatment also depends on where a tumor is located within the lung. RFA is less effective when a tumor is located close to a large blood vessel because the blood carries away the heat too fast, and the treatment temperature may be too low to effectively destroy the tumor cells. Therefore, most lung tumors located in the neighborhood of large blood vessels cannot be treated by RFA. When a lung tumor is close to heat-sensitive structures (like the windpipe and bronchi), the risk of damaging these structures by the heat necessary to kill the tumor cells may be too high, and RFA should not be used.

 

For these reasons, RFA is not used to treat lung tumors that are larger than 3 cm or that are located near the hilum, or root of the lung.

 

Aftercare

 

A patient scheduled for RFA of a lung tumor will be admitted to our ward for about 2- 4 days. You should have a follow-up computed tomography (CT) examination of the chest as an outpatient 6 – 8 weeks after treatment and then every 3 months. Ideally, the CT scans should be performed with contrast. Follow-up imaging is performed to assess the success of RFA and to rule out new lung tumors. You can have follow-up CT as an outpatient in our department or elsewhere. If the CT scan is done at another site, we kindly ask you to send us a CD with the images.

 

For further information on RFA of lung tumors, please do not hesitate to contact us. We will be happy to answer any questions you may have.

 

  • Contact:

Minimally Invasive Tumor Therapy (MITT)

Charité, Campus Virchow-Klinikum

Department of Radiology

Augustenburger Platz 1

13353 Berlin, Germany

Phone: +49 (0)30/450-557309

Fax: +49 (0)30/450-557947

minimal-invasive-ambulanz@charite.de oder mia@charite.de

 

 

Case Example

 

Figure 2: This case illustrates the use of RFA in a patient with a single lung metastasis. The CT scan (first image) obtained before treatment shows a single metastasis (arrow) in the lung. Treatment begins with placement of the RFA probe using CT fluoroscopy for guidance. This allows the radiologist to watch the probe while it is advanced into the tumor. Once the probe has been positioned properly, the interventional radiologist starts to apply the radiofrequency energy (second image). The follow-up CT scan (third image) obtained 2 years after RFA treatment shows scar tissue at the site of ablation.