Clinical Updates
Radiation Oncology
Lung tumors treated with precise high-dose radiation
10/01/2009
Stereotactic body radiation therapy (SBRT) for lung cancer — similar to stereotactic radiosurgery in the brain and spine — focuses high doses of radiation with extreme precision to treat cancerous tumors in just three to five sessions. Using multiple radiation beams that converge on the target area, physicians are able to safely deliver high doses of radiation with very sharp dose gradients to avoid damaging the surrounding tissue.
How SBRT differs from conventional therapy
With conventional therapy, radiation is delivered in relatively small doses over the course of several weeks, with patients receiving daily treatments during that time. With SBRT, physicians are able to deliver a greater combined dose of radiation over the course of far fewer treatments.
SBRT has shown dramatically better outcomes than conventional radiation therapy. Whereas two-year success rates for conventional treatment range from 30 to 40 percent, the success rates for SBRT range from 80 to 90 percent — comparable to those of resection surgery but with far fewer risks.
Despite the fact that SBRT delivers higher biological dosage of radiation, patients have experienced fewer side effects, including radiation pneumonia. Slight fatigue for one week following treatment is SBRT’s most common side effect. How SBRT works Planning begins with diagnostic imaging to help locate the tumor and determine the area that will be treated. This includes four-dimensional imaging that maps the target area as it moves over time with the patient’s breathing cycle.
In the only invasive part of the treatment, gold seeds, called fiducials, are sometimes implanted into the tumor before images are taken. Because the fiducials are visible in planning scans and at the time of treatment, physicians use them to ensure that the high-dose envelope of radiation is accurately overlying the tumor.
Radiation oncologists work with medical physicists to develop a radiation plan that ensures safe exposure to normal structures. Each of the treatment sessions takes 30 to 60 minutes and, unlike with more invasive therapies, the patient leaves each treatment free of significant pain or side effects. Treatments do not have to be administered on consecutive days, but the entire course of therapy is usually concluded within 10 days.
Who can benefit from SBRT
Lung cancer candidates for SBRT are patients with small tumors — five centimeters or less — who are poor candidates for surgery due to the risk of functional deficit.
Patients whose tumors are located centrally or close to airways or the heart have sometimes been considered poor candidates for SBRT due to higher complication rates. UCLA radiation oncologists have successfully treated these patients using slightly lower doses of radiation in combination with radiofrequency ablation. The two treatment modalities offer different toxicity profiles and provide good treatment of tumors with less risk to patients’ breathing function.
UCLA advantage
UCLA’s Department of Radiation Oncology faculty offer the most advanced treatments to patients whose cancers range from the relatively common to the most complex and rare in a caring, patient-focused environment.
UCLA is the first center in the area to install a new, state-of-the-art, image-guided device that provides more accurate, concentrated doses of radiation. Novalis Tx tracks the location of tumors during breathing and other movement, and delivers radiation with the highest precision. The device also shapes the radiation beam, mirroring the tumor’s size and shape.
Novalis Tx is equipped with Varian’s RapidArc radiotherapy technology, delivering precise intensity-modulated radiotherapy (IMRT) up to eight times faster than other IMRT systems. Reducing the treatment time decreases the chance that patient movement will affect the treatment.