With escalating focus on cost containment, there is increasing scrutiny on the practice of multiple stereotactic radiosurgeries (SRSs) for patients with cerebral metastases distant to the initial tumor site. Our goal was to determine the survival patterns of patients with cerebral metastasis who underwent multiple SRSs. We retrospectively analyzed survival outcomes of 801 patients with 3683 cerebral metastases from primary breast, colorectal, lung, melanoma and renal histologies consecutively treated at the University of California, San Diego/San Diego Gamma Knife Center (UCSD/SDGKC), comparing the survival pattern of patients who underwent a single (n = 643) versus multiple SRS(s) (n = 158) for subsequent cerebral metastases. Findings were recapitulated in an independent cohort of 2472 patients, with 26,629 brain metastases treated with SRS at the Katsuta Hospital Mito GammaHouse (KHMGH). For the UCSD/SDGKC cohort, no significant difference in median survival was found for patients undergoing 1, 2, 3, or ≥4 SRS(s) (median survival of 167, 202, 129, and 127 days, respectively). Median intervals between treatments consistently ranged 140-178 days irrespective of the number of SRS(s) (interquartile range 60-300; p = 0.25). Patients who underwent >1 SRSs tend to be younger, with systemic disease control, harbor lower cumulative tumor volume but increased number of metastases, and have primary melanoma (p < 0.001, <0.001, <0.001, 0.02, and 0.009, respectively). Comparable results were found in the KHMGH cohort. Using an independent validation study design, we demonstrated comparable overall survival between judiciously selected patients who underwent a single or multiple SRS(s).
Keywords: Brain metastasis; Gamma knife surgery; Repeat treatment; Stereotactic radiosurgery.