Small cell lung cancer (SCLC) patients with brain metastases who receive focused stereotactic radiosurgery (SRS) live longer than those who receive whole-brain radiation therapy (WBRT), according to research presented this week at the American Society for Radiation Oncology annual meeting in Boston.
In an unexpected secondary finding from a randomized phase 3 clinical trial to compare treatment approaches in this patient population, patients receiving stereotactic surgery lived a median of 17.4 months following treatment. Those who were treated with WBRT lived a median of 8.6 months.
“Although stereotactic radiosurgery is the preferred treatment for brain metastases caused by most other tumors, small cell lung cancer has been an exception where whole brain radiotherapy has remained standard of care” said Chad Rusthoven, MD, co-principal investigator of the trial and a radiation oncologist at the University of Colorado Anschutz School of Medicine in Aurora, Colo. “Our findings suggest that patients can now have a more individualized discussion about whether focused radiosurgery or whole brain treatment is right for them.”
The trial (NRG-CC009) tested SRS against hippocampal-avoidant (HA)-WBRT, a modern, cognitive-sparing form of whole brain that spares the structures involved in memory and was combined with memantine to help protect cognitive function.
“Advances in radiation therapy have fundamentally changed the options for patients with brain metastases,” said Vinai Gondi, MD, lead principal investigator of the trial and director of radiation oncology at the Northwestern Medicine West Region and Proton Center in Warrenville, Ill. “NRG-CC009 reflects how far both approaches have come. For patients with small cell lung cancer, we now have two modern radiation therapy strategies to consider and randomized evidence to help us understand how best to use them.”
After adjustment for patient and disease characteristics, radiosurgery was associated with a 40% lower risk of death, according to the researchers. However, they also cautioned that the trial was not designed or specifically powered to prove a survival benefit.
“At this point, we need to be cautious about assigning a specific cause to the observed differences in survival,” Rusthoven said in an ASTRO statement. “The baseline prognostic factors were well balanced between the treatment arms, but there is always a possibility of imbalances in unmeasured variables. It is also possible that SRS and HA-WBRT may have differential downstream effects on the disease course that affect survival. Further investigation into these areas is needed.”
The researchers noted that radiosurgery did not improve the primary endpoint of time to neurocognitive decline, but also found no significant differences in neurologic death or serious treatment-related side effects.
“Although no differences were observed in neurocognitive function between the treatment arms, the improved survival with SRS addresses a fundamental historical concern with SCLC – that omission of WBRT might lead to worse survival” Gondi said. “Overall, these results support SRS as a reasonable option for patients with brain metastases from SCLC.”
Patients with SCLC have largely been left out of the randomized trials that established radiosurgery as a standard treatment for patients with brain metastases, commented Charles Simone II, MD, Chair of ASTRO’s Lung Cancer Resource Panel and a radiation oncologist at New York Proton Center and Memorial Sloan Kettering Cancer Center.
“This study begins to close that evidence gap and gives clinicians much greater confidence that focused treatment can be a reasonable option for appropriately selected patients,” he said. “The long-term goal is to give each patient the treatment that best fits their disease and priorities rather than defaulting to one approach based on diagnosis alone.”
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