If you have early stage lung cancer, you may undergo a special type of high-energy radiation therapy to treat your cancer.
“Stereotactic body radiation therapy uses very high doses of radiation to a small area of the lungs as a curative treatment for early stage lung cancer,” says Dr. John Cuaron, a radiation oncologist at Memorial Sloan Kettering Cancer Center in New York. Cuaron says that due to lung cancer screening for people at high risk of lung cancers (those with a history of heavy smoking), doctors are finding very small cancers that are amenable to treatment with SBRT.
The standard of care for early stage lung cancer is to surgically remove the tumor. Now, SBRT is also an option for some patients. Cuaron says there are no data from head-to-head clinical trials to compare the two treatment options, although trials are currently underway. However, he says, based on what radiation oncologists know so far, there doesn’t appear to be a big difference in outcomes between the two therapies. “SBRT works about as well as surgery for local control,” he says.
SBRT is a type of external beam radiation therapy, which means it’s delivered from equipment outside of the body (some types of radiation are delivered from radioactive material placed near the tumor). It uses high doses of radiation, targeted precisely at the tumor, which helps spare nearby healthy tissue. SBRT is relatively new technology and has been refined over the past 10 years, says Dr. Terence Williams, a radiation oncologist at The Ohio State University Comprehensive Cancer Center.
[See: 7 Things You Didn’t Know About Lung Cancer.]
Who Is a Candidate for SBRT?
Williams says the classic candidate is someone with a stage 1 lung cancer tumor that’s less than or equal to 5 centimeters in diameter and has not spread to the lymph nodes or other tissue. Sometimes, these patients aren’t good candidates for surgery because they have co-existing medical conditions, such as heart problems. Or, they have limited lung function and wouldn’t do well if a surgeon removed their lung or part of their lung.
SBRT is better for peripheral tumors, those on the external edges of the lungs, because they’re not as close to areas at risk for damage from radiation. “We have to be careful with tumors that are close to the center of the chest,” Cuaron says. SBRT can cause serious risk of damage to nearby structures (for example, the heart), so radiation oncologists will use a gentler dose of radiation. “It’s still safe to treat [tumors centrally located],” he says.
Given a choice, Cuaron says, many patients prefer to have the tumor removed surgically. “It’s a one-time procedure and it’s taken care of,” he says. “I encourage patients to do surgery if they are able to tolerate it until we have definitive trial data to prove SBRT is as good as or better than surgery.”
[See: What Not to Say to Someone With Lung Cancer.]
What Happens During SBRT?
The typical course of SBRT is three to eight treatments every other day for a couple weeks. Each session lasts about 30 to 45 minutes. “The decision regarding the number of treatments is up to the radiation oncologist, who evaluates where the tumor is, what structures are close by and the patient’s overall lung function,” Cuaron says.
Treating lung cancer with radiation therapy is challenging. Every time a patient breathes, the lungs move. This means the tumor is a moving target, as well. Cuaron says part of the prep work before beginning SBRT is to map out the respiratory cycle to determine the volume of lung to target with radiation. Cuaron says that at Memorial Sloan Kettering Cancer Center, doctors use GPS beacons inserted around the tumors so the radiation oncologist knows where the tumor is in space at all times. This makes it possible to be more accurate with treatment and to reduce side effects, he says.
Patients must also be immobilized during treatment with a custom device created during the planning phase. This device keeps them still during their radiation sessions.
Most patients tolerate SBRT well, Williams says; the main side effects are tiredness and a little bit of a cough. They may also have some skin redness or a sore throat. Williams says long-term side effects include scarring of the lungs; radiation pneumonia (which may occur months or years later); and damage to other organs, including the heart, esophagus, spinal cord and nerves. “The risk of developing these side effects is low,” Williams says. “[They impact] less than a few percent of patients. I feel the benefits [of SBRT] outweigh the risks.”
[See: 7 Innovations in Cancer Therapy.]
Lung cancers are deadly, Williams says. Without treatment, they limit patients’ lives. “We know treatment with surgery or radiation benefits patients. SBRT is non-invasive and well tolerated,” he says. “It’s definitely a curative treatment [for early stage lung cancers].”
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What Is SBRT, and When Is It Used for Lung Cancer? originally appeared on usnews.com
