Radiosurgery for brainstem metastases with and without whole brain radiotherapy: clinical series and literature review

Abstract

ObjectiveThe objective of this study was to investigate outcomes for patients with brainstem metastases treated with stereotactic radiosurgery (SRS).MethodsPatients with brainstem metastases treated with SRS between April 2006 and June 2012 were identified from a prospective database. Patient and treatment-related factors were recorded. Kaplan-Meier analysis was used to calculate survival and freedom from local and distant brain progression. Univariate and multivariate Cox regression was used to identify factors important for overall survival.ResultsIn total, 44 patients received SRS for 48 brainstem metastases of whom 33 (75 %) also received whole brain radiotherapy (WBRT): 23 patients (52 %) WBRT prior to SRS, 6 (13.6 %) WBRT concurrently with SRS and 4 (9.0 %) WBRT after SRS. Eight patients received a second course of WBRT at further progression. Median target volume was 1.33 cc (range 0.04–12.17) and median prescribed marginal dose was 15 Gy (range 10–22). There were four cases of local failure, and 6-month and 1-year freedom from local failure was 84.6 and 76.9 %, respectively. Median overall survival (OS) was 5.4 months. There were four cases of radionecrosis, 2 (4.8 %) of which were symptomatic. The absence of external beam brain radiotherapy (predominantly WBRT) showed a trend towards improved OS on univariate analysis. Neither local nor distant brain failure significantly impacted OS.ConclusionThis retrospective series of patients treated with SRS for brainstem metastases, largely in combination with at least one course of WBRT, demonstrates that this approach is safe and results in good local control. In this cohort, no variables significantly impacted OS, including intracranial control.Electronic supplementary materialThe online version of this article (doi:10.1007/s13566-016-0281-4) contains supplementary material, which is available to authorized users.

Toxicity of Radiosurgery for Brainstem Metastases

“…Despite the promising results of SRS with respect to local control and survival, toxicity due to radiation is always a concern, with severe to life threatening toxicities being reported in 0-9.5% of patients with BSM treated with SRS [2][3][4][5][6][7][8][9][10][12][13][14][16][17][18][20][21][22][23][24][25][26][27][28][30][31][32] . Majority of papers have not analyzed the impact of location on toxicity or volume of lesions on toxicity 2-10,12-14,16-18,20-28,30-32 . Due to a relatively small sample size, the preferred dose to treat BSM remains controversial with literature varying on the dosing strategies [2][3][4][5][6][7][8][9][10][12][13][14][16][17][18][20][21][22][23]…”

“…To analyze location based toxicity 1979 cases reviewed, 84 were excluded because there was no comment on location 10,18 and 644 were excluded for lack of location associated with toxicity 17,22 . This resulted in 1251 cases that commented on both location and toxicity.…”

“…To compare treatment and tumor characteristics amongst the substructures, seven reports were examined that commented on both toxicity and location, with patient level data available for 260 cases (of 1251 possible) 6,[15][16][17]21,28,31 . One report was missing tumor volume data for 3 To compare the volumes of the lesions with and without toxicity the same seven reports from the previous paragraph were used.…”

“…One report was missing tumor volume data for 3 To compare the volumes of the lesions with and without toxicity the same seven reports from the previous paragraph were used. This resulted in 260 possible patients that could be analyzed based on patient level data available and development of toxicity 6,[15][16][17]21,28,31 . For the lesions that developed toxicity (n=10) this resulted in a mean volume of 1.6 ± 1.0 cc.…”

“…The reported 79 cases with toxicity were reviewed to summarize patient and treatment factors potentially associated with toxicity. Only 35 of the 79 toxicity cases reported in the literature were described in more detail 2,4,[6][7][8][9]13,14,17,18,21,23,25,27,28,30 . The details of the 35 cases are summarized in Table 3.…”