Stereotactic Radiosurgery Keeps Brain Metastases at Bay

Findings from two clinical trials indicate that stereotactic radiosurgery (SRS) following surgical removal of brain metastases decreases the risk of recurrence and, compared with whole-brain radiotherapy (WBRT), offers patients a better quality of life. As such, postoperative SRS should be considered a new standard of care for patients whose cancer has spread to the brain, according to data presented during the American Society for Radiation Oncology's annual meeting in Boston, MA, September 25–28.

In one multi-institution phase III study, 194 patients whose brain metastases had been resected were randomized to receive SRS or WBRT. According to lead investigator Paul Brown, MD, a radiation oncologist at the Mayo Clinic in Rochester, MN, surgery followed by WBRT to improve intracranial tumor control has been the standard of care for nearly two decades. However, WBRT involves considerable side effects, including complete hair loss that can be permanent, lingering fatigue, and cognitive decline.

With SRS, “we can focus high-dose radiation beams on the surgical cavity with millimeter precision, with minimal damage to surrounding tissue,” he said. “It's an increasingly favored postoperative procedure, despite the lack of clinical trials to substantiate its efficacy, so we decided to directly compare both methods.”

Brown reported that the median overall survival (OS) for patients who received WBRT was 11.5 months compared with 11.8 months for patients who received SRS, which was not statistically significant. Intracranial tumor control was higher with WBRT: The rate at 6 months was 90%, versus 74% with SRS. However, he noted that these patients experienced worse immediate recall and attention than those given SRS, along with a significant decline in physical well-being.

“Given that survival is equivalent whether a patient receives WBRT or SRS, but cognitive function and quality of life are better preserved with the latter, SRS should be considered a less toxic alternative to the historic standard of care,” Brown said.

In a separate prospective clinical trial, Anita Mahajan, MD, a radiation oncologist at The University of Texas MD Anderson Cancer Center in Houston, and colleagues assessed whether surgery is sufficient to control brain metastases, or if postoperative SRS is warranted. In her study, 131 patients were randomized to either an observation-only or an SRS arm after their brain lesions had been removed. Follow-up radiation significantly improved intracranial tumor control, she reported: At 12 months, the rate was 45% in the observation arm, versus 72% with SRS. The median time to local recurrence was 7.6 months for the observation group, and not reached among patients given SRS. There was no difference in the median OS (17 months) between the groups.

“Our results show that postoperative SRS does decrease the likelihood of local recurrence,” Mahajan said. This is especially important for patients who are otherwise responding well to systemic therapy for their disease, she added, because the reappearance of brain metastases would necessitate further surgery, disrupting their clinical management.

“These two studies not only affirm the role of radiation therapy in controlling brain metastases, but also validate the use of SRS, which has a much more favorable toxicity profile” than WBRT, said George Rodrigues, MD, PhD, of the London Health Sciences Center in Ontario, Canada. “As a radiation oncologist, it's good that I'll be better able to inform my next patient about the trade-offs involved with each option.” –Alissa Poh