Scientists gathered in late October for the annual meeting of the American Society for Radiation Oncology (ASTRO), held virtually this year. Among the top stories:
Stereotactic Radiation Just as Effective, With Fewer Side Effects, for Brain Metastases
A phase 3 randomized clinical trial suggests that a type of radiation therapy called stereotactic radiosurgery (SRS) should be the standard of care for treating patients in whom cancer has metastasized, or spread, to four or more sites in the brain. The study was presented October 26 at ASTRO.
A type of therapy called whole brain radiation therapy has been the traditional approach to treating cancer that has spread to several sites in the brain. However, studies on SRS — which uses precisely targeted 3D imaging to apply focused photon beams of radiation — suggest that it is as effective as whole brain radiation without causing side effects like cognitive dysfunction.
The new study found that cognitive function was better preserved in SRS patients compared with the whole brain radiation group. Four months after treatment, 6 percent of the patients in the SRS arm experienced a clinically meaningful decline in cognitive function compared with about half of the patients who received whole brain radiation.
“We believe the results from this phase 3 randomized trial strongly support the use of SRS in patients with 4 to 15 brain metastases to better preserve cognitive function to minimize interruption of systemic therapies,” said the lead author of the study Jing Li, MD, PhD, an associate professor of radiation oncology and director of gamma knife radiosurgery at The University of Texas MD Anderson Cancer Center in Houston.
Breast cancer, lung cancer, and melanoma are the most common primary cancers that tend to spread to the brain. With recent improvements in cancer treatment, patients today are living with these cancers longer, on average. But that means more are experiencing brain metastasis, said Dr. Li.
“Up to 30 percent of cancer patients develop brain metastases at some point during the disease process,” Li said. “Whole brain radiation has been around for a very long time, however it’s been known to be associated with cognitive side effects.” Recent research has looked at ways to treat the metastases without damaging the brain tissue surrounding it.
Previous research on SRS has looked at the benefits of SRS on patients with just one to three brain metastases, Li noted. However, the new study involved 72 adults who had from 4 to 15 untreated, nonmelanoma brain metastases, a number that is considered extensive.
SRS also has the advantage of being less onerous for cancer patients, Li said. Whole brain radiation is typically delivered in 10 sessions over two weeks. SRS is usually delivered in a single session.
The study also showed that patients who received SRS were able to return to other needed cancer treatments, such as chemotherapy, sooner than the patients receiving whole brain radiation.
Overall survival did not differ between the two groups, noted Sue Yom, MD, PhD, a professor of radiation oncology and otolaryngology–head and neck surgery at the University of California in San Francisco. Dr. Yom was not involved in the trial.
“The same overall survival time was maintained,” Yom said. “[SRS patients] lived as long or longer with better neurocognitive function than the patients who got conventional radiation treatment.”
More research is needed to compare SRS with a newer form of whole brain radiation therapy that is designed to spare the hippocampus — the part of the brain involved in learning and memory — from radiation.
"Both options are currently considered standard treatment, and both options have pros and cons. We need randomized data to understand which patients will benefit most from each of these treatments," Li said.
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In Other News From ASTRO
Stereotactic Body Radiation Superior for Spinal Cancer Tumor Pain
Stereotactic body radiation therapy (SBRT) reduces the pain from cancer that has spread to the spine, according to a study presented by Arjun Sahgal, MD, a professor in the departments of radiation oncology and surgery at the University of Toronto and a staff radiation oncologist at Sunnybrook Odette Cancer Centre in Toronto.
Spinal metastases are tumors that have spread from cancer that started in another part of the body. About two-thirds of cancer patients with metastasis experience tumors in the spine, according to previous research.
Spinal tumors are often painful and can cause bone instability as well as neurological symptoms such as weakness, difficulty walking, and bladder and bowel incontinence, Dr. Sahgal said.
The study involved 229 cancer patients whose cancer had spread to the spine. The patients received either SBRT — which involves fewer doses of more focused radiation — or lower-dose conventional radiation. The study found that more than twice as many patients treated with SBRT experienced enduring and complete reduction from pain compared with the conventional therapy group.
The pain relief experienced by the SBRT patients was significant, Sahgal said.
“This is the first phase 3 randomized trial that has shown an improvement with dose escalation for painful spinal lesions,” he said. “Pain deteriorates a patient’s quality of life, and nobody with advanced cancer should have to endure this kind of pain. Patients with painful spinal metastases who meet the eligibility criteria should be offered this treatment.”
Survival rates did not vary between the two groups. Both groups also experienced relatively low rates of adverse events linked to radiation treatment.
“There has been some past controversy about [spinal metastases pain relief], and this is what I consider to be a practice-changing study,” said Yom, who was not involved in the study.
The study also queried patients on the quality-of-life impact of the treatments and found that fewer treatments translated to a financial benefit for patients, Yom added.
“What I find really fascinating about this study is on the quality-of-life surveys,” she said. “Even a difference between two treatments and five treatments was a real difference in the financial orientation of a patient’s quality of life. Being able to have fewer treatments is significant to patients.”
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Proton Therapy for Lung Cancer May Reduce Risk of Heart-Damage
Using proton therapy may cut the risk of radiation-induced heart disease among patients with lung cancer, according to data from researchers at Perelman School of Medicine at the University of Pennsylvania.
Traditionally, radiation treatment for lung cancer has carried a risk of damaging the heart — a phenomenon known as cardiac toxicity. Proton therapy is a type of radiation therapy that more precisely targets the tumor, sparing healthy tissue from radiation exposure and potential damage.
The study of more than 200 patients showed that, with a median of 29 months follow-up, those who had proton therapy had fewer mini strokes and heart attacks compared with those who had standard photon-based radiation therapy.
More research is needed to compare cardiac toxicity from the two treatment methods, the researchers said. “While these findings are promising and add to growing evidence, more research and the results of the randomized trial will help us better determine and understand how treating with protons may reduce cardiac event risk,” said Timothy Kegelman, MD, PhD, chief resident in the department of radiation oncology in the Perelman School of Medicine.
An international phase 3 clinical trial is underway in patients with lung cancer.