Stereotactic radiosurgery for brain metastases: a case-matched study comparing treatment results for patients 80 years of age or older versus patients 65-79 years of age.

Abstract

Recently, an increasing number of patients with brain metastases, even patients over 80 years of age, have been treated with stereotactic radiosurgery (SRS). However, there is little information on SRS treatment results for patients with brain metastases 80 years of age and older. The authors undertook this study to reappraise whether SRS treatment results for patients 80 years of age or older differ from those of patients who are 65-79 years old. This was an institutional review board-approved, retrospective cohort study. Among 2552 consecutive brain metastasis patients who underwent SRS during the 1998-2011 period, we studied 165 who were 80 years of age or older (Group A) and 1181 who were age 65-79 years old (Group B). Because of the remarkable disproportion in patient numbers between the 2 groups and considerable differences in pre-SRS clinical factors, the authors conducted a case-matched study using the propensity score matching method. Ultimately, 330 patients (165 from each group, A and B) were selected. For time-to-event outcomes, the Kaplan-Meier method was used to estimate overall survival and competing risk analysis was used to estimate other study end points, as appropriate. Although the case-matched study showed that post-SRS median survival time (MST, months) was shorter in Group A patients (5.3 months, 95% CI 3.9-7.0 months) than in Group B patients (6.9 months, 95% CI 5.0-8.1 months), this difference was not statistically significant (HR 1.147, 95% CI 0.921-1.429, p = 0.22). Incidences of neurological death and deterioration were slightly lower in Group A than in Group B patients (6.3% vs 11.8% and 8.5% vs 13.9%), but these differences did not reach statistical significance (p = 0.11 and p = 0.16). Furthermore, competing risk analyses showed that the 2 groups did not differ significantly in cumulative incidence of local recurrence (HR 0.830, 95% CI 0.268-2.573, p = 0.75), rates of repeat SRS (HR 0.738, 95% CI 0.438-1.242, p = 0.25), or incidence of SRS-related complications (HR 0.616, 95% CI 0.152-2.495, p = 0.49). Among the Group A patients, post-SRS MSTs were 11.6 months (95% CI 7.8-19.6 months), 7.9 months (95% CI 5.2-10.9 months), and 2.8 months (95% CI; 2.4-4.6 months) in patients whose disease status was modified-recursive partitioning analysis (RPA) Class(es) I+IIa, IIb, and IIc+III, respectively (p < 0.001). Our results suggest that patients 80 years of age or older are not unfavorable candidates for SRS as compared with those 65-79 years old. Particularly, even among patients 80 years and older, those with modified-RPA Class I+IIa or IIb disease are considered to be favorable candidates for more aggressive treatment of brain metastases.