Stereotactic Radiosurgery Best For Cancer Patients With 4+ Brain Metastases

For cancer patients with four or more brain metastases, stereotactic radiosurgery (SRS) reduces cognitive decline compared with whole-brain radiation therapy (WBRT), without compromising overall survival, according to results of a randomized controlled trial.

"This study provides strong evidence to support replacing whole-brain radiation with more focal radiation for patients with multiple brain metastases," lead author Dr. Jing Li, co-director of the Brain Metastasis Clinic at The University of Texas MD Anderson Cancer Center in Houston, said in a news release.

Up to 30% of cancer patients develop brain metastases and the incidence is rising due to prolonged survival and better imaging surveillance, Dr. Li noted in a press briefing October 26 at the American Society for Radiation Oncology (ASTRO) virtual annual meeting, where the findings were presented.

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"In patients with one to three brain metastases, SRS has replaced WBRT as the standard of care due to better preservation of patients' cognitive function, without compromising overall survival, she explained.

The current study compared SRS with WBRT in 72 adults with four to 15 untreated, non-melanoma brain metastases. Memantine was also recommended to patients in the WBRT group based on a recent study finding that the drug can delay cognitive decline in patients receiving WBRT for brain metastases.

At four months, patients in the SRS group scored higher on a standard test of memory function than they did at baseline while those in the WBRT group scored worse (average z-score change from patient's own baseline, +0.21 with SRS vs. -0.74 with WBRT; P=0.04). "We saw similar observations at one month and six months," Dr. Li said.

There was no significant difference in overall survival between the two groups (median, 7.8 months with SRS vs. 8.9 months with WBRT; P=0.59). Local control rates favored SRS, but the difference did not reach statistical significance.

Of note, said Dr. Li, the time to systemic therapy was much shorter with SRS than WBRT (1.7 weeks vs. 4.1 weeks; P=0.001).

"This finding is particularly important because patients with brain metastases oftentimes have metastases outside the brain as well and benefit from systemic therapy to control cancer outside of the brain. But when they receive whole-brain radiation, we typically hold systemic therapy for two weeks," she told the briefing.

Putting the findings in context, briefing moderator Dr. Sue Yom of the University of California, San Francisco, said there has been some "controversy over whether stereotactic radiation should be used for a patient who has numerous cancer metastases in the brain."

This study, conducted in patients with four to 15 brain metastases, "which is considered numerous, showed clearly improved results on neurocognitive testing in those patients who had stereotactic radiation instead of conventional whole-brain radiation therapy," Dr. Yom said.

Dr. Yom also noted that, "as Dr. Li pointed out, giving stereotactic treatment allowed those patients to resume their other treatments such as chemotherapy or other systemic therapies more promptly without an extended interruption, which is very important."

—Megan Brooks

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