How safe and effective is radiosurgical treatment for patients with 10 or more brain metastases?

We evaluated the outcome of radiosurgically treated patients with ≥10 brain metastases (BM), compared to patients <10 BM.

Patients, who underwent at least one Gamma Knife radiosurgical (GKRS) treatment for at least one BM without previous Central Nervous System (CNS) treatments, were retrospectively divided into 2 groups: (1) < 10 or (2) ≥ 10 BM.

At GKRS1, 1293 patients had <10 BM and 126 patients had ≥10 BM. The estimated median survival after GKRS1 was significantly longer in patients with <10 BM (9.9 months), compared to patients with ≥10 BM at GKRS1 (5.3 months; P < .001). Age >65 years (P < .001), male sex (P = .001), Karnofsky Performance Status Scale <80 (P < .001), presence of extracranial metastases (P = .008), presence of neurological symptoms (P = .019), a cumulative BM volume of all BM treated at GKRS1 ≥ 10 cm³ (P = .017), no concomitant immunotherapy or targeted therapy at GKRS1 (P < .001), and the number of ≥10 BM at GKRS1 (P < .001) were identified as independent prognostic factors for an increased risk of death. In patients with ≥10 BM, poor clinical condition, a cumulative BM volume of all BM treated ≥25 cm³, and no concomitant immunotherapy or targeted therapy at GKRS1 were identified as significant independent prognostic factors. The occurrence of post-radiosurgical complications and local tumor control did not differ between the groups.

In addition to BM count, multiple factors may influence survival and should be considered during the pre-radiosurgery assessment. GKRS represents a safe and effective first-line treatment method even for patients with ≥10 BM, particularly in the era of modern systemic therapies.