Study finds longer survival among selected lung cancer patients receiving focused brain radiation treatment.
A clinical trial involving people with small cell lung cancer that had spread to their brain found that focused radiation treatment provided longer overall survival than a modern form of whole brain radiation. Patients who received stereotactic radiosurgery lived an average of 17.4 months, compared with 8.6 months among patients who received hippocampal-avoidant whole brain radiation along with memantine, a drug used to help protect thinking and memory. The findings come from the NRG-CC009 trial, a randomized phase 3 study involving 151 people with small cell lung cancer and brain metastases, and the results were presented at the American Society for Radiation Oncology Annual Meeting this month. Researchers said the study provides new information about treatment choices for patients with this type of cancer, although the trial was not designed to prove that radiosurgery directly caused the longer survival.
Small cell lung cancer has often been treated differently from many other cancers when it spreads to the brain. Whole brain radiation has remained a common treatment because doctors have been concerned that cancer cells too small to see on brain scans could be left behind when only visible tumors are treated.
Stereotactic radiosurgery takes a different approach. Instead of treating the entire brain, the treatment sends high doses of radiation directly to known tumors while limiting radiation exposure to nearby healthy brain tissue. The method has become widely used for brain metastases from several other types of cancer. Patients with small cell lung cancer were mostly left out of earlier studies that helped establish focused radiosurgery as a standard option for other cancers. As a result, there has been less evidence about whether the same approach could safely be used for people with small cell lung cancer.
The new trial compared radiosurgery with a newer form of whole brain radiation designed to reduce some of the effects on memory and thinking. The whole brain treatment spared the hippocampus, an area involved in memory, and was given along with memantine. The main goal was to compare how long patients went before experiencing a decline in memory and other thinking skills. Researchers found no meaningful difference between the two treatment groups on that measure. The finding suggests that the newer whole brain approach may reduce some of the gap in cognitive effects that was seen with older forms of whole brain radiation.
The survival finding was different. Patients receiving stereotactic radiosurgery had a median overall survival of 17.4 months, while those receiving hippocampal-avoidant whole brain radiation and memantine had a median survival of 8.6 months. After researchers adjusted for patient and cancer-related factors, the radiosurgery group had a 40% lower risk of death. Researchers cautioned that the survival result needs further study. Although overall survival was included as a planned secondary measure, the trial was not specifically designed or large enough to establish a survival benefit from radiosurgery. There could also have been differences between patients that were not measured during the study.
The study did not find a significant difference between the groups in deaths caused by problems involving the brain. Serious side effects related to treatment were also similar between the groups. Whole brain radiation did lead to fewer cases of cancer growth in the central nervous system overall, but that difference was not statistically significant after other patient factors were taken into account. The results give both doctors and patients more information to discuss when determining whether radiation treatment for small cell lung cancer that has reached the brain is appropriate. In follow-up studies, factors such as the number and size of brain tumors, other cancer treatment and individual treatment goals can be considered when deciding between all available approaches.
Sources:
Focused radiosurgery extends survival for small cell lung cancer patients with brain metastases
Radiosurgery linked to longer survival for small cell lung cancer with brain metastases
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