A Population-Based Study On The Uptake And Utilization Of Stereotactic Radiosurgery (Srs) For Brain Metastasis In A Canadian Province

Randomized trials, and a number of recent guidelines, have recommended the use of adjuvant Stereotactic Radio-Surgery (SRS) in addition to whole brain radiation therapy (WBRT) for the treatment of brain metastases (BM) in selected patients. This study investigates the rate of utilization and the benefits of SRS in Nova Scotia (NS). The provincial cancer registry was used to identify all patients with primary cancers of the lung, breast, colon/rectum, kidney, melanoma, or ‘unknown-primary’, who had received WBRT from June 2006 through July 2010. Chart review was done for all 710 identified patients, at both the cancer centers in the province. In accordance with our institutional policy, the three criteria used to evaluate a patient's suitability for adjuvant SRS included: Karnofsky performance status (KPS) >=70, 1-3 brain metastatic lesions, and extra-cranial disease controlled or actively being treated, at the time of WBRT. A total of 283 consecutive patients with these ‘good-prognostic’ features were identified and included in the analysis. Median age was 61 years; there were 111 men and 172 women. At diagnosis, 142 (50.2%) had a KPS of >=80, 176 (62.2%) had a single BM, 66 (23.3%) had 2, and 41 (14.5%) had 3 lesions. WBRT was prescribed to a dose of 20Gy/5 (52%), 30Gy/10 (41%), 25Gy/10 (2.3%), or 37.5Gy/15 (1.9%). The majority of patients were treated with WBRT alone (n=166), 44 had WBRT and neurosurgery, and 73 had WBRT and SRS. Median survival was 7.9 months (95% CI: 4.5-9.3). On multivariate analysis, predictors for overall survival (OS) were: age <65 (p<0.05), KPS at diagnosis (p<0.001), controlled primary tumor (p=0.016) and the use of adjuvant SRS (p<0.001). Patients with single-metastasis survived longer than those with 2-3 metastasis (p=0.01). Those who received WBRT and SRS (n=73) survived longer than those treated with WBRT alone (median survival: 17.6 months vs. 4.8 months, p<0.001, 95% CI: 1.99-3.83). OS for those treated with WBRT and SRS was not significantly different from that of WBRT and Surgery (median survival: 13.7 months). Factors associated with an increased utilization rate of SRS include: female gender (p=0.022), age <65 (p=0.018), travel distance to the SRS facility of <300 km (p<0.001), and primary diagnosis of breast cancer (p=0.001). This study provides population-based outcome data for patients with brain metastasis in Nova Scotia, and supports the use and effectiveness of stereotactic radio-surgery following WBRT for selected patients. SRS is currently underutilized in the province, and there is a need to improve access to this technology. In the near future, we anticipate more referrals and increased use of SRS, and thus recommend an expansion of our SRS program.