A Multi-institutional Prospective Observational Study of Stereotactic Radiosurgery for Patients With Multiple Brain Metastases (JLGK0901 Study Update): Irradiation-related Complications and Long-term Maintenance of Mini-Mental State Examination Scores.

PURPOSE: The JLGK0901 study showed the noninferiority of stereotactic radiosurgery (SRS) alone as initial treatment of 5 to 10 brain metastases (BMs) compared with 2 to 4 BMs in terms of overall survival and most secondary endpoints (Lancet Oncol 2014;15:387-95). However, observation periods were not long enough to allow confirmation of the long-term safety of SRS alone in patients with 5 to 10 BMs.

METHODS AND MATERIALS: This was a prospective observational study of Gamma Knife SRS-treated patients with 1 to 10 newly diagnosed BMs enrolled at 23 facilities between March 1, 2009, and February 15, 2012.

RESULTS: The 1194 eligible patients were categorized into the following groups: group A, 1 tumor (n=455); group B, 2 to 4 tumors (n=531); and group C, 5 to 10 tumors (n=208). Cumulative rates of Mini-Mental State Examination (MMSE) score maintenance (MMSE score decrease <3 from baseline) determined with a competing risk analysis of groups A, B, and C were 93%, 91%, and 92%, respectively, at the 12th month after SRS; 91%, 89%, and 91%, respectively, at the 24th month; 89%, 88%, and 89%, respectively, at the 36th month; and 87%, 86%, and 89%, respectively, at the 48th month (hazard ratio [HR] of group A vs group B, 0.719; 95% confidence interval [CI], 0.437-1.172; P=.18; HR of group B vs group C, 1.280; 95% CI, 0.696-2.508; P=.43). During observations ranging from 0.3 to 67.5 months (median, 12.0 months; interquartile range, 5.8-26.5 months), as of December 2014, 145 patients (12.1%) had SRS-induced complications. Cumulative complication incidences by competing risk analysis for groups A, B, and C were 7%, 8%, and 6%, respectively, at the 12th month after SRS; 10%, 11%, and 11%, respectively, at the 24th month; 11%, 11%, and 12%, respectively, at the 36th month; and 12%, 12%, and 13%, respectively, at the 48th month (HR of group A vs group B, 0.850; 95% CI, 0.592-1.220; P=.38; HR of group B vs group C, 1.052; 95% CI, 0.666-1.662, P=.83). Leukoencephalopathy occurred in 12 of the 1074 patients (1.1%) with follow-up magnetic resonance imaging and was detected after salvage whole-brain radiation therapy in 11 of these 12 patients. In these 11 patients, leukoencephalopathy was detected by magnetic resonance imaging 5.2 to 21.2 months (median, 11.0 months; interquartile range, 7.0-14.4 months) after whole-brain radiation therapy.

CONCLUSIONS: Neither MMSE score maintenance nor post-SRS complication incidence differed among groups A, B, and C. This longer-term follow-up study further supports the already-reported noninferiority hypothesis of SRS alone for patients with 5 to 10 BMs versus 2 to 4 BMs.