Radiation Treatments for Spinal Cancers
Spinal tumors can be treated in a variety of ways, and treatment will depend on several factors, including the type, location and size of the tumor as well as the patient's age and general health. Spinal tumors
can be malignant or benign, and may appear as a ‘primary’ tumor site, or as the result of a metastatic cancer, i.e. breast, lung or liver. According to the World Health Organization (WHO 2010), 60 – 84% of cancers spread to the skeletal system, most often the spine.
In some areas of the body, noncancerous tumors aren't particularly worrisome. However, a spinal tumor can cause instability and collapse of the spine, or may directly impinge on nerves – leading to pain, neurological problems and sometimes paralysis.
Surgery on spinal tumors may be used to:
- Relieve compression on the spinal cord
- In some cases, remove the tumor completely.
Radiation therapy or radiosurgery may be used:
- Following surgery to ablate any remaining cancer cells
- Or as a primary method to treat the tumor
Treatment Techniques
Spinal tumors can be treated with external beam radiation therapy (EBRT). With EBRT, the radiation is delivered by a machine called a linear accelerator, or linac, which focuses a high-energy x-ray beam into the tumor site from outside the body. External beam radiation therapy includes radiation therapy (or radiotherapy) and also radiosurgery.
External Beam Radiation Therapy
IGRT, or image-guided radiation therapy, uses sophisticated computer software to analyze a series of image scans of your tumor to create a detailed, three-dimensional picture of the site and your surrounding tissues. The scans typically are produced by computed tomography (CT scan), magnetic resonance imaging (MRI), or positron emission tomography (PET scan). Image-guidance technology enables your team to view the tumor and its position in your body before and during each treatment.
VMAT, or volumetric modulated arc therapy, uses special software and an advanced linear accelerator to deliver treatments up to eight times faster than what was previously possible with standard radiation therapy. Unlike conventional treatments, during which the machine must rotate several times around the patient, or make repeated stops to treat the tumor from a number of different angles, VMAT can deliver the dose to the entire tumor in a single rotation — in as little as two minutes.
IMRT, or intensity modulated radiation therapy, involves changing the intensity of the radiation beam at various angles. At each of these angles, the intensity of the radiation is varied (modulated) and the shape of the beam is changed to suit the shape of the tumor. This directs the prescribed amount of radiation to each part of the tumor, and minimizes exposure to the surrounding healthy tissue.
Radiosurgery is a medical procedure that allows non-invasive treatment of benign and malignant tumors. It is also known as stereotactic radiosurgery (SRS) when used to target tumors in the brain and spine, and stereotactic body radiotherapy (SBRT) when used to target tumors in the body. Radiosurgery uses similar technology to other radiation treatment techniques but differs from conventional radiation therapy treatments in two important ways:
- Rather than having treatment five days a week for 4 to 6 weeks, radiosurgery is delivered in a few very large radiation doses given in five or fewer sessions over one to two weeks.
- Because each treatment delivers very high doses of radiation, the requirement for precision and accuracy is much greater (millimeters vs centimeters) than conventional treatments. Most radiosurgery techniques to the spine are given in one session.
Until recently, radiosurgery was most often used when the patient could not undergo conventional surgery to remove the tumor(s) because of its size or location, or because the person's health was too poor for surgery. However, some physicians consider radiosurgery as the first line of treatment for some tumors.*
* Rock JP, Ryu S, Shukairy MS, Yin FF, Sharif A, Schreiber F, Abdulhak M, Kim JH, Rosenblum ML. (May;58(5):891-8. 2006)
Jin JY, Chen Q, Jin R, Rock J, Anderson J, Li S, Movsas B, Ryu S. (Apr;6(2):127-33.2007)
Benzil DL, Saboori M, Mogilner AY, Rocchio R, Moorthy CR. (Nov;101 Suppl 3:413-418. 2004)
