If you’ve been diagnosed with advanced lung cancer, chances are radiation therapy will be part of your overall treatment plan. Radiation therapy uses high-energy radiation (such as X-rays) to destroy cancer cells or prevent them from growing.
Unfortunately, lung cancer has the highest mortality rate of all diagnosed cancers, says Dr. Gregory Videtic, staff physician and professor of medicine at the Cleveland Clinic Lerner College of Medicine. “Most [lung cancer patients] present with stage 4 cancer, which is incurable. About 50 percent of radiation therapy occurs in the palliative setting to relieve symptoms, improve patients’ quality of life and keep tumors from growing for a time. The reality is that [these treatments] provide a prolonged period of time without symptoms, but it’s not a cure,” Videtic says.
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Radiation treatment can help alleviate pain when lung cancer spreads (metastasizes) to the bone or to treat lung cancer that has spread to the brain. “In the case of brain metastases, chemotherapy doesn’t get past the blood brain barrier [which keeps foreign substances in the blood from entering the brain],” says Dr. Cardinale Smith, an associate professor at Mount Sinai Health System who specializes in hematology and medical oncology, among other topics. “So, radiation may prolong survival. And, if the tumor is blocking an airway, radiation [delivered via endoscopy] may help open it.”
When lung cancer is local — still confined to the lungs and lymph system — doctors treat it with a combination of chemotherapy, surgery and radiation, Videtic says. In these cases, radiation is part of an attempted cure.
There is a minimal role for radiation treatment in early stage lung cancers that are suitable for surgical removal, Smith says. In fact, she adds, studies show that giving radiation after surgery worsens overall survival. “The people who benefit [from radiation therapy] have positive margins,” Smith says. “Radiation helps with local control.” A positive margin means the pathologist finds cancer cells at the edge of the tissue the surgeon removed, which may indicate there are still cancer cells in your body. Radiation therapy may kill these leftover cells.
Stereotactic body radiation therapy may be helpful for people with stage 1 tumors that are less than 5 centimeters in diameter, Smith says. If you undergo SBRT, your radiologist will place you in the exact same position every day for several days and give you very large doses of radiation specifically directed at the tumor. SBRT doesn’t damage nearby healthy tissue as much as traditional radiation. “We don’t know if it’s just as effective as surgery,” Smith says. It’s an option in people who might not be able to tolerate surgery.
The biggest area of innovation in radiation therapy is in these early stage cancers, Videtic says. “[Lung cancer] is completely curable if it’s only in the lung. This accounts for 10 to 15 percent of patients and used to be the domain of surgeons only.”
Many patients have lung and heart problems in addition to lung cancer, Videtic says, and surgery may be too dangerous. Over the past 15 years, technological developments in radiotherapy now allow radiologists to pinpoint these early lung cancers and treat them without damaging other tissues. “For patients who can’t have surgery, instead of not doing anything, we send them for radiation. Stereotactic radiotherapy is not experimental anymore,” Videtic says.
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Radiation Therapy for Small Cell Lung Cancers
Small cell lung cancers account for about 15 percent of all lung cancers. Smith says SCLC patients who had a good response after chemotherapy and radiation treatment may also receive prophylactic (preventive) cranial radiation. PCR decreases the risk of recurrence of SCLC in the brain, helps manage symptoms of metastasized disease and may prolong survival. However, Smith says, it can cause difficulties with cognition, such as short- and long-term memory loss.
The Future of Radiation Therapy
Increasingly, lung cancer treatment is a multidisciplinary effort, Videtic says. It’s a complicated disease, and when the whole lung cancer team (surgeons, oncologists, radiologists and lung specialists) reviews a patient’s case, the expertise of all the specialists means better treatment decisions for patients.
Furthermore, Videtic says radiologists are increasingly finding ways of combining radiation with other treatments, such as immune therapies, which harness the power of the patient’s own immune system. In fact, in a small phase one clinical trial with 98 patients, patients receiving radiotherapy before treatment with pembrolizumab, an immunotherapy, had a 44 percent reduced risk for disease progression and a 42 percent reduced risk for death compared to those who did not receive radiotherapy. According to the researchers, it may be that radiotherapy boosts certain aspects of the immune system, like its ability to recognize tumors, and might even turn some tumors into a type that responds to immunotherapy. For now, however, these therapies are still experimental.
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