CLINICAL ARTICLE
J Neurosurg 136:1307–1313, 2022
Stereotactic radiosurgery for prostate cancer cerebral
metastases: an international multicenter study
Stylianos Pikis, MD,1 Adomas Bunevicius, MD, PhD,1 Cheng-Chia Lee, MD, PhD,2
Huai-Che Yang, MD, PhD,2 Brad E. Zacharia, MD,3 Roman Liščák, MD,4 Gabriela Simonova, MD,4
Manjul Tripathi, MCh,5 Narendra Kumar, MD,6 David Mathieu, MD,7 Rémi Perron,7
Selcuk Peker, MD,8 Yavuz Samanci, MD,8 Jason Gurewitz, BA,9 Kenneth Bernstein, MS,9
Douglas Kondziolka, MD, MSc,10 Ajay Niranjan, MD, MBA,11 L. Dade Lunsford, MD,11
Nikolaos Mantziaris, MSc,12 and Jason P. Sheehan, MD, PhD1
1
Department of Neurological Surgery, University of Virginia Health System, Charlottesville, Virginia; 2Department of
Neurosurgery, School of Medicine, Neurological Institute, Taipei Veterans General Hospital, Taipei, Taiwan, and National
Yang-Ming University, Taipei, Taiwan; 3Department of Neurosurgery, Penn State College of Medicine, Hershey, Pennsylvania;
4
Department of Radiation and Stereotactic Neurosurgery, Na Homolce Hospital, Prague, Czech Republic; Departments of
5
Neurosurgery and 6Radiotherapy, Postgraduate Institute of Medical Education and Research, Chandigarh, India; 7Division
of Neurosurgery, Université de Sherbrooke, Centre de recherché du CHUS, Sherbrooke, Quebec, Canada; 8Department of
Neurosurgery, Koc University School of Medicine, Istanbul, Turkey; Departments of 9Radiation Oncology and 10Neurosurgery,
New York University Langone Medical Center, New York, New York; 11Department of Neurosurgery, University of Pittsburgh,
Pennsylvania; and 12Athens University of Economics and Business, Athens, Greece
OBJECTIVE As novel therapies improve survival for men with prostate cancer, intracranial metastatic disease has
become more common. The purpose of this multicenter study was to evaluate the safety and efficacy of stereotactic
radiosurgery (SRS) in the management of intracranial prostate cancer metastases.
METHODS Demographic data, primary tumor characteristics, SRS treatment parameters, and clinical and imaging
follow-up data of patients from nine institutions treated with SRS from July 2005 to June 2020 for cerebral metastases
from prostate carcinoma were collected and analyzed.
RESULTS Forty-six patients were treated in 51 SRS procedures for 120 prostate cancer intracranial metastases. At
SRS, the mean patient age was 68.04 ± 9.05 years, the mean time interval from prostate cancer diagnosis to SRS was
4.82 ± 4.89 years, and extracranial dissemination was noted in 34 (73.9%) patients. The median patient Karnofsky
Performance Scale (KPS) score at SRS was 80, and neurological symptoms attributed to intracranial involvement were
present prior to 39 (76%) SRS procedures. Single-fraction SRS was used in 49 procedures. Stereotactic radiotherapy
using 6 Gy in five sessions was utilized in 2 procedures. The median margin dose was 18 (range 6–28) Gy, and the
median tumor volume was 2.45 (range 0.04–45) ml. At a median radiological follow-up of 6 (range 0–156) months, local
progression was seen with 14 lesions. The median survival following SRS was 15.18 months, and the 1-year overall
intracranial progression-free survival was 44%. The KPS score at SRS was noted to be associated with improved overall
(p = 0.02) and progression-free survival (p = 0.03). Age ≥ 65 years at SRS was associated with decreased overall survival (p = 0.04). There were no serious grade 3–5 toxicities noted.
CONCLUSIONS SRS appears to be a safe, well-tolerated, and effective management option for patients with prostate
cancer intracranial metastases.
https://thejns.org/doi/abs/10.3171/2021.4.JNS21246
KEYWORDS prostate cancer; brain metastases; stereotactic radiosurgery; oncology
ABBREVIATIONS KPS = Karnofsky Performance Scale; OS = overall survival; SRS = stereotactic radiosurgery; WBRT = whole-brain radiation therapy.
SUBMITTED January 29, 2021. ACCEPTED April 20, 2021.
INCLUDE WHEN CITING Published online October 1, 2021; DOI: 10.3171/2021.4.JNS21246.
©AANS 2022, except where prohibited by US copyright law
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P
rostate cancer accounted for an estimated 1,100,000
new cases and 300,000 deaths in 2012, and globally
it is the second most common malignancy among
men.1 The natural history of prostate cancer is variable,
and when metastatic it most commonly involves the regional lymph nodes, bones, liver, or lungs.2,3
Intracranial dissemination is considered a rare event,
estimated to occur in 0.63% of prostate cancer patients.4
However, with the introduction of new therapies, an increase in the frequency of prostate cancer brain metastases from 0.8% to 2.8% has been reported.5 This increase
was postulated to be related to increasing survival of those
with advanced cancer5 and the inability of new therapies
like docetaxel to cross the blood-brain barrier.6,7
Historically, patients with intracranial prostate metastases have been treated with whole-brain radiation therapy
(WBRT) alone,4,8,9 resulting in a median survival of 4–9
months,4,9 or resection and WBRT, with a mean survival
of 9.2 months reported.10 Nevertheless, intracranial dissemination of prostate cancer usually occurs late in the
disease, and resection of a brain metastasis in prostate
cancer patients may not convey a favorable benefit-to-risk
profile for many such patients. Stereotactic radiosurgery
(SRS) has been proven to be a safe and effective management option for brain metastases from other more common primary malignancies, including melanoma, lung,
and breast. Moreover, SRS has shown promise in extending the overall survival (OS) of patients with intracranial
metastases from prostate cancer, with three small studies
reporting survivals of 9–13 months.4,11,12 However, there
have been no large studies to date investigating the role of
SRS for brain metastasis from prostate cancer.4,11,12
In this international multicenter study, we investigated the safety and efficacy of SRS in the management of
prostate cancer brain metastases. Prognostic factors and
treatment outcomes were also determined following SRS
treatment.
Methods
Data were collected for patients from nine institutions
treated with SRS using the Gamma Knife (Elekta AB) for
cerebral metastases from prostate carcinoma from July
2005 to June 2020. All centers obtained local institutional review board approval to participate in the study, and
patient or next of kin consent was obtained when required.
The pooled data were then de-identified and logged in a
spreadsheet. An International Gamma Knife Research
Foundation (IGKRF) coordinator verified data completeness and compliance with patient protection. The data
were then sent to the institution of the first and last author
for further analysis. Inconsistencies in the data were addressed by the participating centers.
Inclusion criteria for the study included the following:
1) diagnosis of prostate cancer, 2) age > 18 years, 3) no
other malignancy, and 4) SRS of brain metastases.
Clinical Assessment
Data collected included patient demographics and primary tumor characteristics, including prostate cancer histology, date of diagnosis, and treatments received. Regard1308
ing the intracranial metastatic disease, data were collected
on the time from prostate cancer diagnosis to intracranial
dissemination diagnosis; the presence of neurological signs
and symptoms; the patient Karnofsky Performance Scale
(KPS) score and extent of extracranial disease at SRS; the
number, volume, and maximum diameter of intracranial
metastases treated; and prior or concurrent treatments, including concurrent systemic therapy, and WBRT.
SRS Technique
All patients were treated using either frame-based SRS
or a mask-based, frameless stereotactic radiotherapy approach. Radiosurgery was delivered via a Gamma Knife
platform (Elekta AB), although the Gamma Knife model
depended on the year of treatment and availability at each
institution. Prior to treatment, all plans were reviewed and
approved by the radiosurgery team at each participating
institution.
The SRS treatment plans were reviewed, and radiosurgical treatment parameters were collected, including margin dose, maximum dose, number of fractions, and time
interval between fractions.
Radiological and Clinical Follow-Up
Patients were followed clinically and radiographically
at approximately 2- to 3-month intervals after SRS. Neuroimaging was evaluated by the treating neurosurgeon or a
neuroradiologist. Follow-up data collected included local
control, date of local or distant brain metastatic disease
progression, salvage therapy, OS, date of last imaging and
clinical follow-up, date and cause of death, and toxicity
such as radionecrosis. The Common Terminology Criteria for Adverse Events (CTCAE) version 5.0 definitions
were used for scoring radionecrosis.13 OS was defined as
the time period from the day of prostate cancer diagnosis
to last follow-up or death. Intracranial progression-free
survival was measured from the day of first SRS treatment to progression of intracranial disease or death or last
follow-up. Local tumor control was defined as the period
from SRS to neuroimaging-documented progression of
the treated lesion, and local SRS failure was defined as a
radiographic increase in tumor size > 10% after SRS.
Statistical Analysis
Data for continuous variables are presented as median
and range or mean ± SD and for categorical variables as
frequencies and percentages. Kaplan-Meier plots of overall and progression-free survival from the date of SRS
were constructed. Log-rank tests were used to investigate
possible differences between these curves after stratification by various known prognostic factors such as age and
KPS at SRS, number of intracranial metastases, active extracranial disease and presence and location of extracranial metastases, and margin dose. In addition, we analyzed
for an association between clinical outcomes and potential
prognostic factors using univariate and multivariate analysis by Cox regression analysis. Statistical significance was
defined as p < 0.05, and statistics were calculated using
R programming (R Core Team [2016]; R Foundation for
Statistical Computing, https://www.R-project.org).
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Pikis et al.
TABLE 1. Patient demographics and primary tumor
characteristics
Value
No. of pts
Pt age at initial prostate cancer diagnosis, yrs
Pt age at SRS, yrs
Time from initial diagnosis to SRS treatment, yrs
KPS score at SRS
Neurological symptoms present before each SRS
session
Prostate cancer histopathology
Adenocarcinoma
Nonadenocarcinoma
Neuroendocrine carcinoma
Small cell carcinoma
Unknown type
46
62.82 ± 8.95
68.04 ± 9.05
4.82 ± 4.59
80 (50–90)
39 (76.47%)
33 (71.74%)
2 (4.35%)
1 (2.17%)
1 (2.17%)
11 (23.91%)
Pt = patient.
Values are presented as number (%) of patients, mean ± SD, or median
(range) unless otherwise indicated.
Results
Patient and Cancer Attributes
A total of 46 patients were treated in 51 SRS procedures for 120 prostate cancer intracranial metastases. All
patients had a tissue diagnosis of prostate cancer. The histological type of the primary prostate cancer was available
for 35 patients and included 33 adenocarcinomas, 1 tumor
of neuroendocrine histology, and 1 small cell carcinoma.
The mean patient age at the time of prostate cancer diagnosis was 62.82 ± 8.95 years. The mean patient age at
radiosurgery was 68.04 ± 9.05 years, and the mean time
interval from prostate cancer diagnosis to SRS was 4.82 ±
4.89 years (Table 1). Data on extracranial disease activity
at SRS were available for 42 (91.3%) patients. The primary
prostate cancer was reported to be well controlled in 8
(17.4%) patients. At SRS, extracranial dissemination was
noted in 34 (73.9%) patients, including 24 with single-organ involvement (18 patients with osseous, 5 with pulmonary, and 1 with hepatic involvement) and 8 patients with
involvement of two organ systems (7 patients with osseous and pulmonary metastases and 1 patient with hepatic
and osseous metastases). The median patient KPS score
at SRS was 80 (range 50–90), and neurological symptoms
attributed to intracranial involvement were present prior to
39 (76%) SRS procedures (Table 1).
Other Therapies for Extracranial and Intracranial Prostate
Cancer
Eighteen of 46 patients in our series underwent prostatectomy, 11 of whom received adjuvant radiation therapy
to the prostate, while radiation therapy alone was administered to 11 patients. In our series, prior to SRS, 10 patients
underwent craniotomy and resection of a metastatic lesion
and 1 patient underwent transnasal biopsy of a parasellar metastasis. Three patients received WBRT prior to and
2 patients received a WBRT boost immediately after the
TABLE 2. SRS treatment parameters, intracranial metastatic
tumor characteristics, and response of metastases to
radiosurgery and other treatments
Value
Intracranial metastases treated per SRS
session
≤4
>4
Metastasis characteristics
Total no. treated
Diameter, mm
Vol, ml
Radiation dose per metastasis treated, Gy
Margin
Max
Lesion response to SRS at last follow-up
Lesions w/ radiologically observed response
Size unchanged (<10% variance)
Size decreased
Size increased
Lesions w/ unknown response
Op, no. of pts
Craniotomy & resection of metastatic lesion
Biopsy
WBRT timing relative to SRS, no. of pts
Before
After
46 (90.20%)
5 (9.80%)
120
18.39 ± 13.43
5.50 ± 7.41
18 (6–28)
36 (20–75)
82/120 (68.3%)
12/82 (14.63%)
56/82 (68.29%)
14/82 (17.07%)
38/120 (31.66%)
10
1
3
2
Values are presented as number (%) of metastases, mean ± SD, or median
(range) unless otherwise indicated. Local SRS failure was defined as a radiographic increase in tumor size > 10% after SRS.
SRS procedure (Table 2). Antiandrogen therapies (ADTs)
were administered at some point of the disease to 24 patients. At SRS, 11 patients were reported to have castration-resistant prostate cancer, 9 were receiving ADTs, and
4 were receiving systemic chemotherapy.
SRS Parameters
Single-session SRS was utilized in all but 2 patients. Of
these, 1 patient was managed with 5-fraction SRS (margin
dose 6 Gy/fraction). The second patient underwent treatment three times, including one single-session SRS procedure, one 3-fraction SRS procedure (margin dose 9 Gy/
fraction), and one 5-fraction procedure for 4 metastases
(margin dose 6 Gy/fraction). The median diameter of the
120 treated lesions was 17 (range 0.32–60) mm. The median maximum dose was 36 (range 20–75) Gy, and the
median margin dose was 18 (range 6–28) Gy (Table 2).
Local Tumor Response
The radiological response to SRS was available for 82
(68.3%) of 120 treated metastatic lesions (Table 2). The
mean radiological follow-up duration was 16.12 ± 28.97
months, and the median radiological follow-up was 6
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FIG. 1. Kaplan-Meier curve demonstrating the time period of local control per lesion from SRS treatment.
(range 0–156) months. For the 82 lesions with available
radiological response at the last imaging follow-up, 56
(68.29%) decreased in size and 12 (14.63%) remained
stable (Table 2). Thus, local control defined as tumor decrease or stability was achieved in 82.92% of tumors (Fig.
1). The post-SRS 1-year intracranial progression-free survival probability was 44.1% (95% CI 28.2%–69.2%) (Fig.
2). At the last imaging follow-up, 11 patients were noted
to have local progression of 14 (17.07%) lesions. Prior to
SRS, neurological symptoms attributed to the metastases
were present in 10 (90.91%) of 11 and active extracranial
disease was noted in 7 (63.64%) of 11 of these patients.
The mean diameter of these lesions was 15.07 ± 11.74 mm,
and the mean lesion volume was 3.19 ± 4.47 ml. The mean
margin dose to lesions that progressed after SRS was 16.53
± 4.53 Gy. Local progression of the 14 (17.07%) treated lesions was subsequently managed with repeat SRS (n = 11),
WBRT (n = 2), or systemic therapy (n = 1).
Clinical Outcomes After SRS
Clinical follow-up data were available for 41 patients.
The mean clinical follow-up was 19.6 ± 29.62 months,
and the median follow-up was 6 (range 0–156) months.
Neurological symptoms attributed to the target lesion(s)
were reported prior to 39 SRS procedures. According
to Kaplan-Meier calculations, the median OS from time
of prostate cancer diagnosis was 75.3 (range 29.9–169.1)
months, and the median survival following SRS was 15.18
(range 6.51–43.04) months (Fig. 3).
An improved KPS score at SRS was noted in univariate
analysis (p = 0.0009) and multivariate analysis (p = 0.02)
to be associated with improved OS and progression-free
1310
survival (p = 0.03). In multivariate analysis, age ≥ 65 years
at SRS was noted to be associated with decreased OS (p =
0.04). SRS was well tolerated and no grade 3–5 toxicities
were noted. One patient required steroid treatment due to
grade 2 radiation toxicity manifesting as fluctuating mental status. At the last follow-up, 29 (63%) patients had died.
Causes of death included progressive systemic disease in
14 (48.3%), progressive neurological disease in 3 (10.3%),
and sepsis in 2 (6.9%) patients. The cause of death for 10
(34.4%) patients was unknown (Table 3).
Discussion
Brain metastases were historically reported to occur
in < 1% of prostate cancer patients.4,5 However, since the
introduction of docetaxel, which was followed by the chemotherapeutic agent cabazitaxel, the androgen deprivation
agent abiraterone,14 the androgen receptor blocker enzalutamide,15 the vaccine Sipuleucel-T,16 and radium-223,17 the
incidence of prostate cancer brain metastases is expected
to increase as patients have more years at risk with their
disease. Indeed, an increase in the frequency of prostate
cancer brain metastases from 0.8% in the pre-docetaxel
era to 2.8% in the post-docetaxel era was noted in an Italian study.5
Prostate cancer intracranial dissemination usually occurs at the late phase of the disease. It most commonly
involves the epidural space as a result of local invasion
from skull metastases.10 However, since the dura serves as
a barrier to cancer cell dissemination, intradural dissemination is most likely the result of hematogenous spread
with two main potential mechanisms suggested. First,
intradural metastases occur as a single-step process in
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FIG. 2. Kaplan-Meier curve demonstrating patient intracranial progression-free survival from SRS treatment to last follow-up or
death.
FIG. 3. Kaplan-Meier curve demonstrating OS from SRS treatment.
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TABLE 3. Patient outcomes
Value
Pretreatment neurological symptoms post-SRS
(n = 39 SRS sessions)
Resolved
Remained
Unknown
Post-SRS follow-up & survival rates
Clinical follow-up, mos
Radiological follow-up, mos
1-yr post-SRS survival rate (n = 41 pts)
Cause of death (n = 29 pts)
Progressive neurological disease
Progressive systemic disease
Sepsis
Unknown
16 (41.03%)
15 (38.46%)
8 (20.51%)
19.6 ± 29.62
16.12 ± 28.97
23 (56.1%)
3 (10.34%)
14 (48.29%)
2 (6.9%)
10 (34.48%)
Values are presented as number (%) or mean ± SD.
which metastatic prostate cancer cells gain access to the
intradural compartment via the paravertebral venous plexus. Second, spread to the intradural compartment occurs
due to secondary hematogenous spread from a primary
osseous or pulmonary metastasis. The latter mechanism is
supported by the development of intradural metastases late
in the disease and the presence of active systemic disease
in most prostate cancer patients at the time of brain metastasis diagnosis.10 Thus, due to poor OS and evidence of
active extracranial disease, the majority of prostate cancer
patients presenting with brain metastases do not undergo
open cranial resection.18 Without treatment, a median survival of 1 month was reported in a series of prostate cancer
patients with brain metastasis.4 WBRT is associated with
improved outcomes, with one systemic review reporting a
median survival ranging from 4 to 9 months.18
SRS is a minimally invasive procedure that has been
proven to be safe and effective in the management of brain
metastases from cancer types that more commonly metastasize to the brain. However, data concerning the treatment
of prostate cancer brain metastasis with SRS are limited
to three small studies4,11,12 (Table 4). In an analysis from
the Cleveland Clinic, 5 patients with prostate cancer brain
metastases treated with SRS were reported.11 Four had a
single metastasis, while 1 patient had 4 metastases. Three
patients received SRS alone, 1 received both WBRT and
SRS, and 1 patient received a combination of surgery,
WBRT, and SRS. All patients were initially symptomatic, but all improved neurologically and in KPS score at 3
months post-SRS. In this small case series, local intracranial control was 100%, with no new intracranial lesions reported. The same series also reported a mean OS of 10.0 ±
6.7 months, with 2 patients dying from conditions unrelated to prostate cancer, 2 dying from systemic progression,
and 1 patient alive and asymptomatic at last follow-up.11
The second published study included 10 patients with intracranial metastatic prostate cancer treated with SRS.12 In
total, 15 brain metastases were treated: 9 dural-based and
6 parenchymal. Six patients had a single metastasis and 4
patients had multiple metastases. Eight patients carried the
diagnosis of adenocarcinoma, while a subset of 2 patients
had small cell carcinoma. The patients received a combination of SRS, partial brain radiation therapy, WBRT, and
surgery. A median margin SRS dose of 16 Gy yielded a
local control rate of 85%, which included patients receiving upfront and boost SRS, as well as those undergoing
salvage SRS. In 2 patients, disease progressed despite fractionated partial brain radiation therapy. One of 3 patients
subsequently developed new distant brain metastases, and
1 patient needed repeat SRS for recurrence. Overall, the
median survival in that series was 13 months.12 TremontLukats et al. reported a median survival of 9 months in
a small series of 5 patients managed with SRS for brain
metastatic disease from prostate cancer.4
Our study is the largest and only multicenter SRS study
for prostate cancer patients with brain metastasis. It confirms the reported effectiveness of SRS in the management
of prostate cancer patients with brain metastases. The median patient survival in our series was 15.18 (range 6.51–
43.04) months, and at last follow-up, local tumor control
was seen in 82.9% (68/82) of the treated lesions. A KPS
score > 70 was noted to be associated with improved OS
(p = 0.02) and improved local control of the treated lesion
(p = 0.03). Age ≥ 65 years at SRS (p = 0.04) and active
extracranial disease (p = 0.03) were associated with decreased OS and distant intracranial disease progression,
TABLE 4. Series of patients treated with radiosurgery for prostate cancer brain metastases
Authors
& Year
No. of
Pts
Histology
Total Brain
Mean Tumor
Median
12-Mo Local
Overall
Severe Toxicity
Metastases Treated
Vol
Margin Dose
Control
Survival (mos) (grade 3–5)
Tremont-Lukats et al.,
20034
Kim et al., 200811
Flannery et al., 201012
5
NR
NR
NR
NR
NR
9*
None
5
10
8
15
3.1 ml
7.7 ml
NR
16 Gy
100%
85%
10†
13*
None
None
Present study
46
AD
8 AD, 2 small cell
carcinoma
33 AD, 2 non-AD
120
5.50 ml
18 Gy
83%
15*
None
AD = adenocarcinoma; NR = not reported.
* Median OS.
† Mean OS.
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Pikis et al.
respectively. SRS for brain metastases from prostate cancer appears to be a safe and well-tolerated procedure with
a low risk of complications reported in the literature.4,11,12
In our series, there was 1 patient who developed grade 2
radiation toxicity that was managed with corticosteroids.
As novel systemic therapies are more regularly employed, brain metastases from prostate cancer will likely
increase in frequency. SRS appears to be a safe, well-tolerated, and overall effective management option for patients
with prostate cancer intracranial metastases. A median
survival of 15 months and local intracranial control were
achieved in the vast majority of brain metastases treated
with SRS. There were no serious grade 3–5 toxicities noted. Further, well-designed studies evaluating the efficacy
of SRS in combination with adjuvant treatments are necessary to improve outcomes of patients with intracranial
dissemination from prostate cancer.
9. Lawton A, Sudakoff G, Dezelan LC, Davis N. Presentation,
treatment, and outcomes of dural metastases in men with
metastatic castrate-resistant prostate cancer:a case series.
J Palliat Med. 2010;13(9):1125–1129.
10. Salvati M, Frati A, Russo N, et al. Brain metastasis from
prostate cancer. Report of 13 cases and critical analysis of the
literature. J Exp Clin Cancer Res. 2005;24(2):203–207.
11. Kim SH, Chao ST, Toms SA, et al. Stereotactic radiosurgical treatment of parenchymal brain metastases from prostate
adenocarcinoma. Surg Neurol. 2008;69(6):641–646.
12. Flannery T, Kano H, Niranjan A, et al. Stereotactic radiosurgery as a therapeutic strategy for intracranial metastatic
prostate carcinoma. J Neurooncol. 2010;96(3):369–374.
13. National Cancer Institute. Common Terminology Criteria
for Adverse Events (CTCAE). Version 5.0. Accessed June
3, 2021. https://ctep.cancer.gov/protocolDevelopment/
electronic_applications/docs/CTCAE_v5_Quick_Reference_
8.5x11.pdf
14. Fizazi K, Scher HI, Molina A, et al. Abiraterone acetate for
treatment of metastatic castration-resistant prostate cancer:
final overall survival analysis of the COU-AA-301 randomised, double-blind, placebo-controlled phase 3 study.
Lancet Oncol. 2012;13(10):983–992.
15. Scher HI, Fizazi K, Saad F, et al. Increased survival with
enzalutamide in prostate cancer after chemotherapy. N Engl J
Med. 2012;367(13):1187–1197.
16. Kantoff PW, Higano CS, Shore ND, et al. Sipuleucel-T immunotherapy for castration-resistant prostate cancer. N Engl
J Med. 2010;363(5):411–422.
17. Parker C, Nilsson S, Heinrich D, et al. Alpha emitter radium-223 and survival in metastatic prostate cancer. N Engl J
Med. 2013;369(3):213–223.
18. Sita TL, Petras KG, Wafford QE, et al. Radiotherapy for cranial and brain metastases from prostate cancer:a systematic
review. J Neurooncol. 2017;133(3):531–538.
Acknowledgments
Disclosures
References
Author Contributions
Study Limitations
Limitations of this multicenter study include its retrospective nature, patient selection bias, and limited statistical power. The lack of imaging follow-up for 38 of
120 SRS-treated cerebral metastases represents another
limitation of our study. Nevertheless, clinical and imaging
follow-up were available for 41 (89%) of 46 patients and
for 82 cerebral metastases, respectively. Thus, the current
study represents the largest to date in a relatively rare cancer histology for brain metastasis formation.
Conclusions
This research study (IRRF-02-04-2020) was supported by a
grant from the International Radiosurgery Research Foundation
(IRRF).
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4. Tremont-Lukats IW, Bobustuc G, Lagos GK, et al. Brain
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5. Caffo O, Veccia A, Fellin G, et al. Frequency of brain metastases from prostate cancer:an 18-year single-institution
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6. van der Veldt AA, Hendrikse NH, Smit EF, et al. Biodistribution and radiation dosimetry of 11C-labelled docetaxel in
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Dr. Zacharia: speakers bureau, NICO Corp.; consultant,
Medtronic. Dr. Lunsford: direct stock ownership, Elekta AB; consultant, Insightec Data Safety Monitoring Board.
Conception and design: Sheehan. Acquisition of data: Pikis,
Bunevicius, Lee, Yang, Zacharia, Liščák, Simonova, Tripathi,
Kumar, Mathieu, Perron, Peker, Samanci, Gurewitz, Bernstein,
Kondziolka, Niranjan. Analysis and interpretation of data:
Sheehan, Pikis, Bunevicius, Mantziaris. Drafting the article:
Sheehan, Pikis. Critically revising the article: Sheehan, Pikis,
Lee, Yang, Zacharia, Liščák, Simonova, Tripathi, Mathieu, Peker,
Kondziolka, Niranjan, Lunsford. Reviewed submitted version of
manuscript: Sheehan, Pikis, Bunevicius, Lee, Yang, Zacharia,
Liščák, Simonova, Tripathi, Kumar, Mathieu, Peker, Samanci,
Gurewitz, Bernstein, Kondziolka, Niranjan, Lunsford. Approved
the final version of the manuscript on behalf of all authors:
Sheehan. Statistical analysis: Mantziaris. Study supervision:
Sheehan.
Correspondence
Jason P. Sheehan: University of Virginia Health System,
Charlottesville, VA. jsheehan@virginia.edu.
J Neurosurg Volume 136 • May 2022
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