What is SBRT (Stereotactic Body Radiotherapy)?

SBRT for Primary Lung Cancer and Oligometastases

doctor and nurse with patient in radiation therapy suite
How is stereotactic body radiotherapy (SBRT) used for people with lung cancer?. Istockphoto.com/Stock Photo©Trish233

Definition: SBRT (Stereotactic Body Radiotherapy)

SBRT (stereotactic body radiotherapy) is a relatively new procedure for treating lung cancer that uses high doses of radiation delivered to a precise target. By using special positioning and implanted markers in the body, radiologists are able to deliver a much higher dose of radiation to a cancer than traditional radiation therapy, while sparing healthy tissue.

Uses for Stereotactic Body Radiotherapy (SBRT) in People with Lung Cancer

At this time, there are 3 primary reasons why SBRT may be used with lung cancer.

  • With lung cancer, SBRT is typically used for early stage, small lung cancers (non-small cell lung cancer) who are unable to have surgery for some reason. A lung cancer could be considered inoperable lung cancer due to the location of the tumor, or other health conditions which could make lung cancer surgery risky.
  • For elderly patients who may be expected to do poorly with surgery or have medical conditions which may raise the risk of surgery complications.
  • For one or a few areas of spread of the lung cancer or metastasis (oligometastases.)

SBRT Procedure

Stereotactic body radiotherapy uses a high dose of radiation delivered to a very precise region of tissue.  This is in contrast to conventional radiation therapy for lung cancer which uses a much smaller dose of radiation given over time.

 Radiologists map out coordinates in 4 dimensions to accurately define the area to be treated.

Stereotactic Body Radiotherapy (SBRT) for Primary Lung Cancer

SBRT can sometimes work as effectively as surgery for some people with small non-small cell lung cancers which are otherwise inoperable, or in patients who have medical conditions which could make surgery dangerous.

SBRT has resulted in control of the disease comparable to surgery, and long-term survival has been possible in people carefully chosen for the procedure. Tumors need to be small, usually less than 5 cm (2-3 inches) in diameter, and not be too close to the airways or the heart.

Stereotactic Body Radiotherapy (SBRT) for Oligometastases

In the past, the presence of metastases limited treatment options to chemotherapy, and survival less than a year was the rule. For people that have only one or a few areas of lung cancer metastases (spread) the use of SBRT has changed that somewhat. It's been found that for people with oligometastases (oligo means literally "few') treating the metastases with SBRT has increased median survival rates and there have been some people who have survived long term due to this treatment.  

Lung cancer most commonly spreads to the brain, bones, the liver, and the adrenal glands, with SBRT used most often for people with liver metastases and brain metastases due to lung cancer.

Due to advances in the treatment of oligometastases - such as SBRT - it has become possible for some people with lung cancer to experience extended periods of disease-free survival with a better quality of life than would otherwise be possible.

Possible Complications of SBRT

There are many potential complications of SBRT for lung cancer, similar to side effects of conventional radiation therapy such as fatigue and radiation pneumonitis. Two of the more common complications of SBRT used for lung cancer include:

  • Brachial plexopathy - Radiation can damage nerves in an area called the brachial plexus.  This may result in pain in the arm or shoulder, with weakness and then numbness of the hand and wrist.
  • Chest wall pain or dysfunction - If a tumor is near the chest wall, scar tissue may cause pain and restriction.

The Future

Early results showing results with SBRT comparable to lung cancer surgery raise the hope that, for some people anyway, SBRT may be used as a less invasive alternative to lung cancer surgery in the future. It's also likely that, with better treatments of lung cancer now being approved and in clinical trials, and with initial results found with metastases, that SBRT may also be used further to remove sites of metastatic tumor.

Also Known As: stereotactic radiotherapy, stereotactic radiosurgery, stereotactic radiation therapy

Sources:

Ashworth, A., Rodriques, G., Boldt, G., and D. Palma. Is there an oligometastatic state in non-small cell lung cancer? A systematic review of the literature. Lung Cancer. 2013. 82(2):197-203.

Ashword, A., Senan, S., Palma, R. et al. An individual patient data metaanalysis of outcomes and prognostic factors after treatment of oligometastatic non-small-cell lung cancer. Clinical Lung Cancer. 2014. 15(5):346-55.

Griffoen, G., Toquri, D., Dahele, M. et al. Radical treatment of synchronous oligometastatic non-small cell lung carcinoma (NSCLC): patient outcomes and prognostic factors. Lung Cancer. 2013. 82(1):95-102.

Guerrero, E., and M. Ahmed. The role of stereotactic ablative radiotherapy (SBRT) in the management of oligometastatic non small cell lung cancer. Lung Cancer. 2015. (Epub 2015 Dec 2).

Ricardi, U., Badellino, S., and A. Filippi. Stereotactic body radiotherapy for early stage lung cancer: History and updated role. Lung Cancer. 2015. 90(3):388-96.

Salama, J., and S. Schild. Radiation therapy for oligometastatic non-small cell lung cancer. Cancer Metastasis Review. 2015. 34(2):183-93.

Continue Reading