RFA and SBRT Treatment of Lung Cancer
Treatment for primary lung cancer and lung metastases may consist of the surgical removal of the cancer, radiation therapy, or systemic treatment with chemotherapy, immunotherapy, or precision cancer medicines. When a non-lung cancer spreads to the lungs from other sites in the body doctors say it has “metastasized”. Lung metastases are common among patients diagnosed with advanced breast, colon, and prostate cancers as well as melanoma and other solid tumors.
Some patients that might benefit from surgical removal of the cancer are not able to undergo surgery because they are too elderly, suffer from other medical conditions such as heart disease, or have diminished lung capacity making it difficult to withstand surgery. These patients are often offered radiation therapy alone as treatment for their cancer. Unfortunately, radiation therapy can cause severe side effects which can further compromise lung function.
Image guided therapies that deliver radiation directly to the cancer, while sparing healthy tissue from destruction have been developed and may be used to treat early-stage NSCLC patients ineligible for surgery and isolated lung metastases. The most widely used approaches are Stereotactic body radiation therapy (SBRT) and Radiofrequency ablation (RFA).1-7
Stereotactic body radiation therapy (SBRT) utilizes precisely targeted radiation delivered to the cancer while minimizing radiation to adjacent normal tissue. Treatment is delivered over 3-5 days. This targeting allows treatment of small- or moderate-sized tumors in either a single or limited number of dose fractions.
Radiofrequency ablation (RFA) is a minimally invasive technique that uses heat to destroy cancer cells. During RFA, an electrode is placed directly into the tumor; the procedure is guided by a CT scan, ultrasound, or laparoscopy. The electrode’s high frequency radio waves create intense heat, which destroys the cancer cells.
Surgery vs Radiation Therapy
Although SBRT allows individuals who are poor surgical candidates to receive effective treatment, surgery may still be preferred over radiation therapy as treatment for early-stage NSCLC. Analyses presented at the 2023 meeting of the American Association for Thoracic Surgery suggests individuals who are good surgical candidates have a five-year survival rate that’s 15 percentage points lower if they are treated with radiation instead of surgery.
Researchers analyzed data on more than 30,000 individuals with early-stage NSCLC who treated between 2012 and 2018 and compared the outcomes of 24,700 patients treated with surgical resection with nearly 6,000 who underwent targeted stereotactic body radiation therapy (SBRT).8
Three months after treatment surgical or radiation therapy outcomes were similar but the overall five-year survival rates were 71% for people treated with surgery compared with only 42% for those who were treated with radiation. Individuals often choose radiation therapy because they are too frail to undergo surgery, so the researchers analyzed a subgroup of 528 patients who were healthy enough to undergo surgery but elected radiation therapy instead. Their five-year survival rate compared to those who got surgery was 56% significantly worse than the 71% achieved with surgery.
Clinical trials directly comparing surgery versus radiation are ongoing in individuals with early-stage NSCLC.
The RAPTURE clinical study initially evaluated the use of RFA in 106 patients with either NSCLC or lung metastases, with the site of cancer within the lung measuring 3.5 centimeters in diameter or smaller. All patients were considered ineligible for treatment with chemotherapy or radiation therapy. Patients underwent RFA and were followed for two years.6
- Completion of therapy was achieved in 99% of patients.
- There were no treatment-related deaths
- 88% of patients achieved a complete disappearance of cancer at the site of RFA, which lasted for at least one year.
- Overall survival at one year was 70%, 89%, and 92%, respectively, for patients with NSCLC, patients with lung metastases from colorectal cancer, and those with metastases from other sites.
- Overall survival at two years was 48%, 66%, and 64%, respectively, for patients with NSCLC, those with lung metastases from colorectal cancer, and those with metastases from other sites.
- Only 8% of patients diagnosed with Stage I NSCLC died from their cancer at two years.
Both SBRT and RFA appear to produce similar outcomes. Researchers have compared the effectiveness of RFA and SBRT in 6,195 stage IA NSCLC patients who were ineligible for surgery and received SBRT or RFA between 2004 and 2015. The one, three, and five-year survival rates were 83%, 48%and 29%. Patients receiving RFA seemed to have slightly better survival than those receiving SBRT if their cancers were very small (<1cm in diameter).7
Radiofrequency Ablation (RFA)
Radiofrequency ablation (RFA) uses heat made by radio waves to treat cancer. RFA is delivered in the imaging department of the hospital, and it takes about 30 minutes.
The doctor will inject a local anesthetic into the chest wall so that the area is numb. A CT scanner is used to show the position of the cancer and then the doctor puts a small probe (like a needle) through the chest wall directly into the cancer. An electrode in the probe creates radiofrequency energy to produce heat and destroy the cancer.
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Side Effect of RFA
Soreness and pain may occur at the RFA site. Some patients will experience fatigue. A potential complication of the procedure is a collapsed lung (pneumothorax). This can occur when air or gas leaks into the space around the lung. and make it collapse. The main symptom is shortness of breath. A pneumothorax can resolve on its own or your doctor can put in a small tube to expand the lung again.
Stereotactic body radiation therapy (SBRT)
Stereotactic radiosurgery uses many precisely focused radiation beams to treat tumors. It is not surgery in the traditional sense because there's no incision. Instead, stereotactic radiosurgery uses 3D imaging to target high doses of radiation to the affected area with minimal impact on the surrounding healthy tissue.
Like other forms of radiation, stereotactic radiosurgery works by damaging the DNA of the targeted cells. The affected cells then lose the ability to reproduce, which causes tumors to shrink.
Doctors use three types of technology to deliver radiation during stereotactic radiosurgery in the brain and other parts of the body:
- Linear accelerator (LINAC) machines use X-rays (photons) to treat cancerous and noncancerous abnormalities in the brain and other parts of the body. LINAC machines are also known by the brand name of the manufacturer, such as CyberKnife and TrueBeam. These machines can perform stereotactic radiosurgery (SRS) in a single session or over three to five sessions for larger tumors, which is called fractionated stereotactic radiotherapy.
- Gamma Knife machines use 192 or 201 small beams of gamma rays to target and treat cancerous and noncancerous brain abnormalities. Gamma Knife machines are less common than LINAC machines and are used primarily for small to medium tumors and lesions in the brain associated with a variety of conditions.
- Proton beam therapy (charged particle radiosurgery) is the newest type of stereotactic radiosurgery and is available in only a few research centers in the U.S, although the number of centers offering proton beam therapy has greatly increased in the last few years. Proton beam therapy can treat brain cancers in a single session using stereotactic radiosurgery, or it can use fractionated stereotactic radiotherapy to treat body tumors over several sessions.
Preparing for SBRT
Before SBRT can be delivered some patients will need to undergo placement of gold or other type of metal markers called fiducials (fih-DOO-shul). Fiducials are about the size of a grain of rice and are used to mark the tumor. They can be seen on an x-ray and act as a tracking device for the treatment machine to follow.
A thoracic surgeon will use a needle to place the fiducial(s) in your lung under local anesthesia 1 to 3 weeks before radiosurgery treatment. Typically, from 1 to 4 fiducials are placed. They cannot be felt, are not magnetic or radioactive and cannot be removed.
Treatment planning: About 1 week after consultation and/or placement of the fiducials, patients have a treatment-planning CT scan. A custom-molded “cradle” is made so the patient can lie motionless during treatment.
The CT scan is done with you in the cradle and/or vest. The CT images are sent to the planning computer. Once the CT scan is complete, the radiation oncologist and thoracic surgeon develop a custom plan according to information in the computer regarding your tumor. Planning your treatment may take 1 to 2 weeks.
During the treatment the therapist will positions you on the treatment table in your vest and/or cradle. The therapist will leave the room and watch you closely on a monitor. The treatment can take up to 1 1/2 hours.
SBRT Side effects
There are minimal side effects associated with SBRT treatment for lung cancer. The most common side effects are fatigue and a dry cough which can result from irritation of the airway. The cough usually goes away within 1 month after the last treatment.
Temporary changes to the skin in the area that was treated may occur. Changes may include redness, dryness, scaling, and itchiness of the treated area. These skin changes usually occur 1 to 2 days after your treatment and lasts 1 to 2 weeks after your treatment.
References:
- de Baere T, Palussiere J, Auperin A, et al. Midterm Local Efficacy and Survival after Radiofrequency Ablation of Lung Tumors with Minimum Follow-up of 1 Year: Prospective Evaluation. Radiology. 2006; 240:587-596.
- Ambrogi M, Lencioni R, Fontanini G, et al. Percutaneous radiofrequency ablation of primary NSCLC. Proceedings from the 11th World Conference on Lung Cancer, Barcelona, Spain. 2005; Abstract #Pr1.
- Belfiore G, Moggio G, Tedeschi E, et al. CT-Guided Radiofrequency Ablation: A Potential Complementary Therapy for Patients with Unresectable Primary Lung Cancer-A Preliminary Report of 33 Patients. American Journal of Roentgenology. 2004; 183: 1003-1011.
- Nguyen CL, Scott WJ, Young NA et al. Radiofrequency Ablation of Primary Lung Cancer. Chest. 2005;128:3507-3511.
- Lencioni R, Crocetti L, Cioni R, et al. Response to radiofrequency ablation of pulmonary tumours: a prospective, intention-to-treat, multicentre clinical trial (the RAPTURE study. Lancet Oncology. 2008; 9:621-628.
- Iyengar P, Kavanagh B, WArdak Z, et al. Phase II Trial of Stereotactic Body Radiation Therapy Combined With Erlotinib for Patients With Limited but Progressive Metastatic Non–Small-Cell Lung Cancer. Journal of Clin Oncol. Published online before print October 27, 2014, doi: 10.1200/JCO.2014.56.7412
- https://pubmed.ncbi.nlm.nih.gov/33854605
- https://ww2.aievolution.com/aats/index.cfm?do=abs.viewAbs&abs=4104
