scholarly journals The Impact of Cobalt-60 Source Age on Biologically Effective Dose in Stereotactic Radiosurgery Thalamotomy

2016 ◽  
Vol 96 (2) ◽  
pp. E563
Author(s):  
B.H. Kann ◽  
J.B. Yu ◽  
J. Bond ◽  
C. Loiselle ◽  
V.L. Chiang ◽  
...  
Keyword(s):  
Effective Dose ◽  
Stereotactic Radiosurgery ◽  
Biologically Effective Dose ◽  
The Impact

scholarly journals The Impact of Insulin-Like Growth Factor Index and Biologically Effective Dose on Outcomes After Stereotactic Radiosurgery for Acromegaly: Cohort Study

Neurosurgery ◽  
2020 ◽  
Vol 87 (3) ◽  
pp. 538-546 ◽  
Author(s):  
Christopher S Graffeo ◽  
Diane Donegan ◽  
Dana Erickson ◽  
Paul D Brown ◽  
Avital Perry ◽  
...  
Keyword(s):  
Cohort Study ◽  
Growth Factor ◽  
Effective Dose ◽  
Stereotactic Radiosurgery ◽  
Univariate Analysis ◽  
Biologically Effective Dose ◽  
Insulin Like Growth Factor ◽  
Biochemical Remission ◽  
The Impact

Abstract BACKGROUND Stereotactic radiosurgery (SRS) is a safe and effective treatment for acromegaly. OBJECTIVE To improve understanding of clinical and dosimetric factors predicting biochemical remission. METHODS A single-institution cohort study of nonsyndromic, radiation-naïve patients with growth hormone-producing pituitary adenomas (GHA) having single-fraction SRS between 1990 and 2017. Exclusions were treatment with pituitary suppressive medications at the time of SRS, or <24 mo of follow-up. The primary outcome was biochemical remission—defined as normalization of insulin-like growth factor-1 index (IGF-1i) off suppression. Biochemical remission was assessed using Cox proportional hazards. Prior studies reporting IGF-1i were assessed via systematic literature review and meta-analysis using random-effect modeling. RESULTS A total of 102 patients met study criteria. Of these, 46 patients (45%) were female. The median age was 49 yr (interquartile range [IQR] = 37-59), and the median follow-up was 63 mo (IQR = 29-100). The median pre-SRS IGF-1i was 1.66 (IQR = 1.37-3.22). The median margin dose was 25 Gy (IQR = 21-25); the median estimated biologically effective dose (BED) was 169.49 Gy (IQR = 124.95-196.00). Biochemical remission was achieved in 58 patients (57%), whereas 22 patients (22%) had medication-controlled disease. Pre-SRS IGF-1i ≥ 2.25 was the strongest predictor of treatment failure, with an unadjusted hazard ratio (HR) of 0.51 (95% CI = 0.26-0.91, P = .02). Number of isocenters, margin dose, and BED predicted remission on univariate analysis, but after adjusting for sex and baseline IGF-1i, only BED remained significant—and was independently associated with outcome in continuous (HR = 1.01, 95% CI = 1.00-1.01, P = .02) and binary models (HR = 2.27, 95% CI = 1.39-5.22, P = .002). A total of 24 patients (29%) developed new post-SRS hypopituitarism. Pooled HR for biochemical remission given subthreshold IGF-1i was 2.25 (95% CI = 1.33-3.16, P < .0001). CONCLUSION IGF-1i is a reliable predictor of biochemical remission after SRS. BED appears to predict biochemical outcome more reliably than radiation dose, but confirmatory study is needed.

The Impact of Insulin-Like Growth Factor Index and Biologically Effective Dose on Outcomes After Stereotactic Radiosurgery for Acromegaly: Cohort Study

Neurosurgery ◽  
2021 ◽  
Vol 89 (Supplement_2) ◽  
pp. S9-S9
Author(s):  
Christopher S Graffeo ◽  
Diane Donegan ◽  
Dana Erickson ◽  
Paul D Brown ◽  
Avital Perry ◽  
...  
Keyword(s):  
Cohort Study ◽  
Growth Factor ◽  
Effective Dose ◽  
Stereotactic Radiosurgery ◽  
Biologically Effective Dose ◽  
Insulin Like Growth Factor ◽  
Factor Index ◽  
The Impact

scholarly journals Biologically effective dose correlates with linear tumor volume changes after upfront single-fraction stereotactic radiosurgery for vestibular schwannomas

2021 ◽  
Author(s):  
Constantin Tuleasca ◽  
Mohamed Faouzi ◽  
Philippe Maeder ◽  
Raphael Maire ◽  
Jonathan Knisely ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Effective Dose ◽  
Stereotactic Radiosurgery ◽  
Tumor Volume ◽  
Vestibular Schwannomas ◽  
Benign Tumors ◽  
Biologically Effective Dose ◽  
Volume Changes ◽  
Single Fraction

AbstractVestibular schwannomas (VSs) are benign, slow-growing tumors. Management options include observation, surgery, and radiation. In this retrospective trial, we aimed at evaluating whether biologically effective dose (BED) plays a role in tumor volume changes after single-fraction first intention stereotactic radiosurgery (SRS) for VS. We compiled a single-institution experience (n = 159, Lausanne University Hospital, Switzerland). The indication for SRS was decided after multidisciplinary discussion. Only cases with minimum 3 years follow-up were included. The Koos grading, a reliable method for tumor classification was used. Radiosurgery was performed using Gamma Knife (GK) and a uniform marginal prescription dose of 12 Gy. Mean BED was 66.3 Gy (standard deviation 3.8, range 54.1–73.9). The mean follow-up period was 5.1 years (standard deviation 1.7, range 3–9.2). The primary outcome was changes in 3D volumes after SRS as function of BED and of integral dose received by the VS. Random-effect linear regression model showed that tumor volume significantly and linearly decreased over time with higher BED (p < 0.0001). Changes in tumor volume were also significantly associated with age, sex, number of isocenters, gradient index, and Koos grade. However, the effect of BED on tumor volume change was moderated by time after SRS and Koos grade. Lower integral doses received by the VSs were inversely correlated with BED in relationship with tumor volume changes (p < 0.0001). Six (3.4%) patients needed further intervention. For patients having uniformly received the same marginal dose prescription, higher BED linearly and significantly correlated with tumor volume changes after SRS for VSs. BED could represent a potential new treatment paradigm for patients with benign tumors, such as VSs, for attaining a desired radiobiological effect. This could further increase the efficacy and decrease the toxicity of SRS not only in benign tumors but also in other SRS indications.

scholarly journals The Impact of Insulin-like Growth Factor Index and Biological Effective Dose on Outcomes After Stereotactic Radiosurgery for Acromegaly

Neurosurgery ◽  
2019 ◽  
Vol 66 (Supplement_1) ◽  
Author(s):  
Christopher S Graffeo ◽  
Diane Donegan ◽  
Dana Erickson ◽  
Paul D Brown ◽  
Avital Perry ◽  
...  
Keyword(s):  
Growth Factor ◽  
Effective Dose ◽  
Stereotactic Radiosurgery ◽  
Univariate Analysis ◽  
Cox Proportional Hazards ◽  
Insulin Like Growth Factor ◽  
Biological Effective Dose ◽  
Biochemical Remission ◽  
The Impact

Abstract INTRODUCTION Stereotactic radiosurgery (SRS) is a safe and effective adjuvant treatment for acromegaly. Clinical and dosimetric factors predicting biochemical remission are incompletely understood. METHODS A single-institution cohort study of non-syndromic, radiation-naïve patients with growth hormone producing pituitary adenomas (GHA) having single-fraction SRS between 1990 and 2017. Patients were excluded if they were receiving pituitary suppressive medications at the time of SRS or if they had < 24 mo of follow-up. The primary outcome was biochemical remission defined as normalization of insulin-like growth factor-1 index (IGF-1i) off suppressive medications. Biochemical remission was assessed using Cox proportional hazards. RESULTS A total of 102 patients met study criteria. Forty-six (45%) were female, median age was 49 yr (IQR = 37–59), median follow-up was 63 mo (IQR = 29–100). Median pre-SRS IGF-1i was 1.66 (IQR = 1.37–3.22). Median margin dose was 25 Gy (IQR = 21–25); median estimated biological effective dose (BED) was 169.49 Gy (IQR = 124.95–196.00). Biochemical remission was achieved in 58 (57%) patients, whereas 22 patients (22%) had medication-controlled disease. IGF-1i was the strongest independent predictor of remission, with an unadjusted hazard ratio (HR) of 0.53 (95% CI = 0.36–0.75, P < .0001). Number of isocenters, margin dose, and BED predicted remission on univariate analysis, but after adjusting for sex and baseline IGF-1i, only BED remained independently associated with outcome in both continuous (HR = 1.01, 95% CI = 1.00–1.01, P = .02) and binary models (HR = 2.27, 95% CI = 1.39–5.22, P = .002). Twenty-four (29%) developed new post-SRS hypopituitarism. CONCLUSION IGF-1i is a better predictor of biochemical remission after SRS than IGF-1 level. BED appears to predict biochemical outcome more reliably than radiation dose, but confirmatory study is needed.

Progressive Vestibular Schwannoma following Subtotal or Near-Total Resection: Dose-Escalated versus Standard-Dose Salvage Stereotactic Radiosurgery

2020 ◽  
Author(s):  
Alexander D. Sherry ◽  
Mohamed H. Khattab ◽  
Nauman Manzoor ◽  
Douglas J. Totten ◽  
Guozhen Luo ◽  
...  
Keyword(s):  
Effective Dose ◽  
Stereotactic Radiosurgery ◽  
Local Control ◽  
Vestibular Schwannoma ◽  
Standard Dose ◽  
Binary Logistic Regression ◽  
Biologically Effective Dose ◽  
Total Resection ◽  
Dose Cohort ◽  
Neurologic Sequelae

Abstract Objectives Local failure of incompletely resected vestibular schwannoma (VS) following salvage stereotactic radiosurgery (SRS) using standard doses of 12 to 13 Gy is common. We hypothesized that dose-escalated SRS, corrected for biologically effective dose, would have superior local control of high-grade VS progressing after subtotal or near-total resection compared with standard-dose SRS. Design Retrospective cohort study. Setting Tertiary academic referral center. Participants Adult patients treated with linear accelerator-based SRS for progressive VS following subtotal or near-total resection. Main Outcome Measures Dose-escalated SRS was defined by a biologically effective dose exceeding a single-fraction 13-Gy regimen. Study outcomes were local control and neurologic sequelae of SRS. Binary logistic regression was used to evaluate predictors of study outcomes. Results A total of 18 patients with progressive disease following subtotal (71%) and near-total (39%) resection of Koos grade IV disease (94%) were enrolled. Of the 18 patients, 7 were treated with dose-escalated SRS and 11 with standard-dose SRS. Over a median follow-up of 32 months after SRS, local control was 100% in the dose-escalated cohort and 91% in the standard-dose cohort (p = 0.95). Neurologic sequelae occurred in 28% of patients, including 60% of dose-escalated cohort and 40% of the standard-dose cohort (p = 0.12), although permanent neurologic sequelae were low at 6%. Conclusions Dose-escalated SRS has similar local control of recurrent VS following progression after subtotal or near-total resection and does not appear to have higher neurologic sequalae. Larger studies are needed.

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