Stereotactic Radiosurgery For Brain Metastases Research Articles

Frameless Fractionated Stereotactic Radiosurgery for Brain Metastases: An Institutional Series of 89 Cases

<h3>Purpose/Objective(s)</h3> Cobalt-60 stereotactic radiosurgery (SRS) conventionally involves frame-based immobilization and single-fraction treatment. However, certain anatomical and technical factors, including large lesion size, close proximity to critical structures, and prior radiation treatment, necessitate fractionated SRS, which requires mask-based immobilization. We present a large institutional experience with mask-based fractionated SRS for large, retreated, or critically-located brain metastases. <h3>Materials/Methods</h3> All patients treated with frameless fractionated SRS for brain metastases between March 2017 and August 2021 at a single institution were identified. Patient, tumor, and treatment variables were abstracted. The primary outcome was one-year local control (LC), which was analyzed with the Kaplan-Meier method. This study was approved by the institution's IRB. <h3>Results</h3> Seventy-four patients with a total of 89 brain metastases were treated. The median follow-up time was seven months. The median age at treatment was 64 years. Sixty-two percent of patients were female. The most common primary tumors were breast (24.7%), non-small cell lung (24.7%), small-cell lung (7.9%), renal cell (6.7%), and melanoma (6.7%). For the majority (62.9%) of tumors, the indication for fractionation was retreatment; other indications were large size (21.3%), critical location (12.4%), and medical comorbidity (3.4%). For all tumors, the mean maximal linear size was 35.5 mm; for tumors fractionated due to size, the mean size was 45.8 mm. The median total dose was 2,750 cGy (range: 1,620-3,000), and the median dose per fraction was 600 cGy (range: 405-900); the most common dose-fractionations were 3,000 cGy in 600 cGy per fraction (42.7% of patients) and 2500 cGy in 500 cGy per fraction (31.5% of patients). The mean target volume was 17.6 cc (range: 0.13-120.0), and the mean maximum dose was 4,980 cGy (range: 3,240-6,000). For 91% of treatments, the prescription isodose line was 50 to 59% (mean, 54%). Target coverage was 100% in all but one case, where it was 99%. For lesions near the brainstem, mean brainstem maximum point dose (MPD) was 9.78 Gy and mean brainstem mean dose was 3.56 Gy. For lesions near the optic pathway, mean optic nerve MPD was 14.39 Gy, mean optic nerve mean dose was 6.2 Gy, mean optic chiasm MPD was 11.7 Gy, and mean optic chiasm mean dose was 5.4 Gy. LC at 12 months was 91%. Nineteen percent of patients experienced acute grade 1-2 toxicity; one patient experienced acute grade 3 fatigue, and there was no other grade 3 or higher acute toxicities. Seventeen percent of patients had grade 1-2 radiation necrosis (RN); there were no cases of grade 3 or higher RN. <h3>Conclusion</h3> Cobalt-60 frameless fractionated SRS for brain metastases offers excellent local control. This treatment modality is technically feasible, offers excellent sparing of critical structures, and has minimal toxicity. Frameless fractionated SRS should be considered for large, retreated, or critically located metastases.

Long-Term Survivors of Stereotactic Radiosurgery for Brain Metastases: Do Distant Brain Failures Reach a Plateau and what Factors are Associated with a Brain Metastasis Velocity of Zero?

<h3>Purpose/Objective(s)</h3> Life expectancy continues to increase for patients with brain metastases treated with stereotactic radiosurgery (SRS), and as such, questions regarding how long patients need surveillance imaging have become more relevant. The present study sought to retrospectively analyze brain metastasis patients who have survived two years or more, and assess for what factors may predict for a final brain metastasis velocity (BMV) of "zero." <h3>Materials/Methods</h3> This was a single-institution retrospective study of 300 patients treated with SRS from 2001 to 2019 for brain metastases without prior whole brain radiotherapy (WBRT) who survived greater than two years after first SRS. Clinical outcomes were determined via the Electronic Medical Record. Final BMV is calculated by summing all metastases through the observed time divided by the total time in years. A BMV of zero is defined as at least two years of imaging follow-up without distant brain failure (DBF). The cumulative incidence of DBF is via the Fine Gray Method and defined from time of first SRS to time of DBF. <h3>Results</h3> Of the 300 patients in this review, median age at first SRS is 61 (IQR: 53, 70). Primary cancers include lung cancer (50%), breast cancer (16%), melanoma (15%), GU primary (11%), GI primary (4%) and other (4%). Median number of metastases at first SRS is one (IQR: 1, 3). Median follow-up is three years (IQR: 2.3, 5.1). Kaplan-Meier estimated median overall survival is 4.9 years. In this patient population, the median Kaplan-Meier estimated time to DBF is 1.5 years (95% CI: 1.2, 2.0). Twenty-eight (9.3%) patients underwent subsequent WBRT. One hundred and one (33.7%) patients never had any further brain metastases (BMV = 0) at a median follow-up time of 3.3 years. Median BMV is 0.4 (IQR: 0, 1.4). Distant brain failures appear to reach a plateau at four years where the cumulative incidence of DBF is 82%. Seventy percent of first time DBFs have occurred by two years. Factors significantly associated with a BMV of zero include fewer brain metastases at first SRS (HR 1.1; p = 0.0004) and Caucasian race (HR 1.5; p = 0.03). <h3>Conclusion</h3> Approximately one third of brain metastasis patients who live beyond two years after initial SRS have a BMV of zero. DBFs appear to reach a plateau at four years, after which very few patients develop new brain metastases if they have not yet already. Factors significantly associated with a BMV of zero include Caucasian race and having had a single brain metastasis at first SRS.

Clinical Factors Associated with Radionecrosis Following Stereotactic Radiosurgery in the Era of Modern Systemic Therapy

<h3>Purpose/Objective(s)</h3> Stereotactic radiosurgery (SRS) is commonly utilized in the treatment of brain metastases; however, radiation necrosis (RN) is a dose-limiting toxicity. Systemic therapy has greatly improved in recent years with the advent of immunotherapy and targeted therapy leading to increased overall survival. Here, we examined the impact of clinical factors on development of RN after SRS for brain metastasis in the era of modern systemic therapy. <h3>Materials/Methods</h3> We retrospectively reviewed patients treated with Linac-based SRS at a single institution from 2015-2020. Overall survival was calculated using the Kaplan-Meier method. Univariable (UVA) and multivariable (MVA) analysis was performed using Cox proportional hazards modeling. Covariates included age, sex, race, ethnicity, ECOG, primary cancer site, neurologic deficits at diagnosis, seizures, number/size of tumors, benign vs. malignant disease, prior systemic therapy, post-op vs. intact SRS, whole brain radiotherapy before or after SRS, edema at diagnosis, receipt and timing of immunotherapy/targeted therapy. Concurrent therapy was defined as within 30 days of SRS. <h3>Results</h3> 412 patients treated with SRS to 950 lesions were identified at a median follow-up of 8 months. Median age was 63 (interquartile range [IQR] 54-70) with 90% ECOG 0-1. At presentation, 53% had neurologic deficits and 7.6% had seizures. 82% were treated for malignant disease. 30% received post-op SRS. Prior to SRS, treatment included 1-9 lines of systemic therapy (58%), immunotherapy (24%), and WBRT (7.4%). SRS was given for 1-5 lesions in 91% of patients. Median tumor diameter was 2.0 cm (IQR 1.2-2.8). Median OS was 35 months (95% confidence interval [CI] 21-50); 1- and 2-year OS were 68% (95% CI 75-84) and 54% (95% CI 63-73). 17% developed radiographic RN with a median time to RN of 10 months (95% CI 9-13). Of 68 patients who developed RN, those with clinical symptoms (65%) were successfully treated with steroids (65%), laser interstitial thermal therapy (47%), bevacizumab (10%), and craniotomy (21%). On UVA, factors predictive of time to RN included post-op SRS (HR 1.84, 95% CI 1.12-3.00, p=0.015), number of treated lesions (HR 1.11, 95% CI 1.03-1.21, p=0.011), size of largest lesion (HR 1.46, 95% CI 1.17-1.81, p=0.001), malignant tumor (HR 4.17, 95% CI 1.49-11.11, p=0.006), prior systemic therapy (HR 1.7, 95% CI 1.1-2.86, p=0.046), and vasogenic edema at diagnosis (HR 1.97, 95% CI 1.19-3.26, p=0.008). On MVA, for every 1 cm increase in diameter of the largest lesion, the likelihood of developing RN was increased 1.45-fold (95% CI 1.12-1.88, p=0.005). Timing of systemic therapy did not impact RN rate. <h3>Conclusion</h3> Our data demonstrate that RN occurs in ∼17% of patients at a median of 10 months following SRS and can be successfully managed with medical and surgical therapies. The strongest predictor of RN was the size of the treated tumor. Our findings highlight the need for continued clinical surveillance as improved systemic therapy leads to increased long-term survival.

Outcomes of Stereotactic Radiosurgery for Brain Metastases in Patients with Small-Cell Lung Cancer

<h3>Purpose/Objective(s)</h3> Several randomized studies have established stereotactic radiosurgery (SRS) as a first-line treatment modality for limited brain metastases. However, these trials frequently excluded patients with primary small cell lung cancer (SCLC). Here, we assess clinical outcomes of patients with primary SCLC who have undergone SRS for brain metastases. <h3>Materials/Methods</h3> We identified patients with histologically-proven SCLC who underwent first-time SRS for brain metastases at our institution. Overall survival, local recurrence, and time to distant CNS failure were estimated with the Kaplan-Meier method. Univariate log-rank test and multivariate Cox regression were used to assess the significance of prognostic factors including age, sex, prior whole brain radiation, number of brain metastases, and extracranial disease control status. <h3>Results</h3> Fifty-nine patients (median age 64) with SCLC completed SRS for brain metastases at our institution from July 2007 to December 2021. 88.1% (n=52) of patients received Gamma Knife SRS, whereas the remainder received LINAC-based SRS. 61.0% (n=36) had received prior whole brain or prophylactic cranial irradiation. The median number of treated brain metastases was 2 (range 1-11) with a median tumor diameter of 1.0 cm and a marginal dose of 18 Gy. Median overall survival was 11 months. On multivariate Cox regression, both increased number of brain metastases (HR 1.22; 95% CI 1.02-1.44) and increased age (HR 1.09; 95% CI 1.03-1.16) were associated with poorer overall survival. 11.9% (n=7) of patients experienced local recurrence at a median of 5 months post-SRS (range 2-9 months). The median time to distant CNS failure was 6 months. Multivariate analysis identified extracranial disease control status as the sole significant predictor of distant failure. Log-rank test demonstrated that the patient cohort with uncontrolled extracranial disease had a lower time to distant failure compared to those with stable or well-controlled disease (4 vs. 22 months; p=0.0001). <h3>Conclusion</h3> SRS provides excellent local control of SCLC-associated brain metastases without compromising overall survival. Our institutional data support the rationale for future prospective studies to establish the role of intracranial SRS in this patient population.

5 Year Survivors from Brain Metastases Treated with Stereotactic Radiosurgery: Biology, Improving Treatments or Just Plain Luck?

<h3>Purpose/Objective(s)</h3> Improvements in therapies have led to an increasing number of long-term survivors of brain metastases. This population has not been well characterized. The present series compares a population of 5-year survivors of brain metastases to a generalized brain metastasis population to assess for factors attributable to long term survival. <h3>Materials/Methods</h3> A single institution retrospective review was performed to identify 5-year survivors of brain metastases who have received stereotactic radiosurgery (SRS). Electronic medical records were queried to characterize this population based on clinical, demographic and treatment data. A historical control population of 747 patients with brain metastases was used to assess for similarities and differences between the long-term survivor population and the general population treated with upfront SRS. Statistical analysis was performed with SAS version 9.4 using the 2-sample t test, chi squared test, and Fine Gray competing risk analysis using death as a competing risk. <h3>Results</h3> From 9/99 to 2/17 a total of 2422 patients were treated with SRS for brain metastases at a single institution, where 95 patients (3.9%) were found to have survived over 57 months. In the historical control population, 25 of 747 patients (3.3%) lived beyond 57 months. In the long-term survivor cohort, primary tumors were from lung (53%), melanoma (19%), breast (12%), renal cell (9.5%) and other histology (7.4%). Median survival of the long-term survivor cohort was 85 months, with mean number of 2.2 (SD=2.0) metastases treated and 2% receiving WBRT prior to SRS. Two-sample t-test test found no difference between long term survivors and controls with regards to age (p=0.2), primary cancer distribution (p=0.7), number of metastases (p=0.9), insurance type (p=0.1) or median income level (p=0.3). 22% of long-term survivors were receiving systemic therapy at last follow-up, and 52% showed no evidence of clinical disease at the last follow-up. Cumulative incidence of neurologic death at 6, 8 and 10 years for the long-term survivor cohort was 5%, 15%, and 15%, respectively. In the historical controls, cumulative incidence of neurologic death reached a plateau at 34% after 4.9 years. 61% of long-term survivors received further SRS (median 2, range 2-9, IQR 2.3), while 7% received post SRS WBRT. 5-year survivors received more additional SRS (P<0.0001), while historical controls received more post SRS WBRT (P=0.0008). <h3>Conclusion</h3> Five-year survivors of brain metastasis represent a diverse histologic population, suggesting that biologically, for each cancer type, a small population of oligometastatic and indolent cancers exist. While neurologic death of this long-term survivors is lower than in historical controls, these patients can still, die of neurologic death.

Hippocampal Dosimetry and Neurocognitive Function in Patients Undergoing Stereotactic Radiosurgery for Brain Metastases

Abstract AIMS To measure neurocognitive function (NCF) and correlate with hippocampus dose in patients undergoing stereotactic radiosurgery (SRS) for 1-3 brain metastases. METHOD We conducted a prospective observational study measuring NCF before and after SRS in patients with 1-3 brain metastases and correlated changes with hippocampal dosimetry Patients underwent NCF testing at baseline, 1 month, 3 months and 6 months post SRS and quality of life was measured at each time point. NCF tests included Hopkin’s Verbal learning test, controlled oral word association test and trail making tests. Hippocampus was outlined in line with RTOG guidance and dose was collected from the treatment planning system. RESULTS 36 patients were recruited. Mean age was 64 years, median WHO performance status 1 (range 0-2). At baseline, 65% of patients displayed NCF impairment in at least 1 NCF domain and 33% didn’t exhibit any neurological symptoms. Asymptomatic patients has underlying diagnosis of non-small cell lung cancer or melanoma. NCF impairment was evident at 1, 3 and 6 months for 50%, 66% and 40% patients respectively. Decline at 1 month was associated with higher median dose to 0.1cc of hippocampus (5 Gy vs 2.35 Gy). Association with hippocampal dose and NCF impairment at 3 and 6 months was not observed. CONCLUSION A significant proportion of patients exhibited impaired NCF at baseline with greatest NCF decline seen at 1 months and subsequent recovery of NCF evident at 6 months. Dose to hippocampus 0.1cc may be associated with acute NCF toxicity. Main limitations of this study was small number of patients.

P11.45.B Improved overall survival following Stereotactic Radiosurgery for brain metastases - a single institution experience

Abstract Background Brain metastases are increasingly common due to longer survival associated with advancements in treatment. Approximately 40% of cancer patients are diagnosed with brain metastases at some point during their disease. Stereotactic radiosurgery (SRS) avoids the neuro-cognitive toxicity associated with whole brain radiotherapy and has been increasingly offered as a treatment alternative for brain metastases. Combined with developments in systemic treatments, this approach has resulted in improved overall survival (OS). This study reviewed patients treated with single fraction SRS at our institution with a primary endpoint of overall survival. Material and Methods A retrospective review determined overall survival for 237 patients who received single fraction SRS for 451 brain metastases from solid tumours between 1st January 2017 and 31st December 2021. Primary tumour sites were classified as breast, kidney, colorectal, melanoma, lung or other. SPSS v.27 was used for Kaplan Meier OS determination. The median follow up was 10.3 months. Cox regression analysis assessed the association between Gross Tumour Volume (GTV) and OS. Results In this patient cohort, 60% (N=142) were female and 40% (N=95) were male, with a median age of 63 [32-85]. 63.7% (N = 151) had a solitary metastasis. Patients received a single fraction of 15, 17.5 or 20 Gy (prescribed to 80% isodose) dependent on the planning target volume (PTV) size and whether it was initial treatment or re-treatment. 71% of all patients were alive at 6 months with median OS of 12.0 months [10.6-13.4]. Primary tumour site significantly affected OS (Log rank, Chi squared 15.656, p0.008) with breast cancer patients (N=58) surviving longest with a median OS 16.0 months [13.6-18.4] followed by melanoma median OS 15.0 months [7.6-22.4], kidney cancer patients (N = 24) median OS 12.0 months [8.3-15.7] and lung patients (N=87) median OS 10.0 months [8.9-11.3]. The lowest median OS was for colorectal patients at 7.0 months [1.4-12.6]. However, considering the small sample size, N = 15, more data is needed to confirm the significance. The larger the GTV volume the lower the survival time (Chi squared 8.692, p 0.003). Conclusion 71% of patients had an OS of 6.0 months or more with a median of 12.0 months. As expected, primary tumour site has a significant impact on OS, with breast cancer patients living longest. In addition, increasing GTV size is associated with significantly worse survival. Given the improved survival for these patients, the avoidance of neuro cognitive decline remains of paramount importance and outcomes for these patients need to be reported in future work.

PL01.6.A Radiomics outperforms semantic features for prediction of response to stereotactic radiosurgery in brain metastases

Abstract Background Brain metastases show different patterns of contrast enhancement, potentially reflecting hypoxic and necrotic tumor regions with reduced radiosensitivity. An objective evaluation of these patterns might allow a prediction of response to radiotherapy. We therefore investigated the potential of MRI radiomics in comparison with the visual assessment of semantic features to predict early response to stereotactic radiosurgery in patients with brain metastases. Material and Methods In this retrospective study, 150 patients with 308 brain metastases from solid tumors (NSCLC in 53% of patients) treated by stereotactic radiosurgery (single dose of 17-20 Gy) were evaluated. The response of each metastasis (partial or complete remission vs. stabilization or progression) was assessed within 180 days after radiosurgery. Patterns of contrast enhancement in the pre-treatment T1-weighted MR images were either visually classified (homogenous, heterogeneous, necrotic ring-like) or subjected to a radiomics analysis. Random forest models were optimized by cross-validation and evaluated in a hold-out test data set (30% of metastases). Results In total, 221/308 metastases (72%) responded to radiosurgery. The optimal radiomics model comprised 10 features and outperformed the model solely based on semantic features in the test data set (AUC, 0.71 vs. 0.56; accuracy, 69% vs. 54%). The diagnostic performance could be further improved by combining semantic and radiomics features resulting in an AUC of 0.74 and an accuracy of 75% in the test data set. Conclusion The developed radiomics model allowed prediction of early response to radiosurgery in patients with brain metastases and outperformed the visual assessment of patterns of contrast enhancement.

P11.11.B Stereotactic radiosurgery for brain metastases;outcome and prognostic factors in patients treated with single-fraction and multiple-fractions

Abstract Background Stereotactic radiosurgery (SRS) is preferred to whole brain radiotherapy (WBRT) for the treatment of patients with a limited number of brain metastases, both as primary treatment and after surgery. SRS can be delivered in a single fraction (SF) or in multiple fractions (MF) depending on tumor size and location. The aim of this single-center retrospective study was to evaluate intracranial control and overall survival (OS) in patients who received SF and MF SRS for brain metastases. Material and Methods All patients treated with primary SRS for brain metastases at Aarhus University Hospital between 2015 and 2020 were identified. Independent of undergoing surgery, SF SRS (20 Gy) was administered for targets (gross tumor volume) &amp;lt;2 cm in diameter and MF SRS (24-27 Gy in 3 fractions) for targets &amp;gt;2 cm. SRS was not combined with WBRT. Treatment response was evaluated by 3-monthly MRI-scan. To evaluate intracranial control, first events were scored as local-only failure (tumor progression at the SRS treatment site), distant failure (tumor progression not at the SRS site), and combined failure (local and distant failure). Actuarial incidence of local failure (local-only and combined) and OS were estimated using the Kaplan-Meier method. To analyze the association of SF and MF SRS with local failure and OS, multivariable Cox regression analyses were used. Results The consecutive cohort consisted of 196 patients treated for 275 brain metastases. The most frequent primary disease was non-small cell lung cancer (NSCLC n=96), followed by renal cell carcinoma (n=26) and breast cancer (n=22). SRS was delivered to 1 (n=133), 2 (n=49), 3 (n=12), and 4 (n=2) targets per patient. SF and MF SRS was used in 99 (51%) and 97 (49%) patients, respectively. In 40 patients, SRS was administered after surgery (SF n=7, MF n=33). At a median (range) follow-up of 10 (0-93) months, 111 (57%) patients had intracranial progression, and 159 (81%) patients died. Local-only/distant/combined failure rate was 23 and 42%/59 and 35%/18 and 23%, in SF and MF SRS respectively. The median time to local failure was respective 9.0 (95% CI 5.4-12.6) and 6.0 (95% CI 5.0-7.0) months in the SF and MF SRS group. SF SRS and surgery were independently associated with a longer time to local failure. Salvage WBRT, SRS, and re-operation were performed in respective 36, 13, and 26 patients. Histopathological radiation necrosis was observed in 5 patients. All patients with necrosis had a primary diagnosis of NSCLC, and 4/5 patients were treated with SF SRS. For the total group, the median OS was 10.0 (95% CI 8.0 - 12.0) months. PS&amp;lt;2, surgery, stable extracranial disease and SF SRS were associated with a longer survival. Conclusion MF SRS was associated with a higher rate of and shorter time to local failure, and was a poor prognostic factor for survival, which is in line with the selection of patients with more unfavorable brain metastases for this treatment.

LOCL-10 EVOLUTION OF FUNCTIONAL OUTCOMES AFTER LASER INTERSTITIAL THERMAL THERAPY (LITT) VERSUS RESECTION IN THE TREATMENT OF LESIONS IN OR NEAR THE PRIMARY MOTOR CORTEX

Laser interstitial thermal therapy (LITT) has become increasingly common, particularly in the treatment of progressive lesions after stereotactic radiosurgery for brain metastases. Previous work has illustrated the sensitivity to its use near critical structures, including the corticospinal white matter tracts. A single-surgeon retrospective study was performed of patients who underwent LITT or open resection for lesions located in or near the primary motor cortex, with functional outcomes graded relative to pre-treatment symptoms at 30, 90, and 180 days. Forty patients met inclusion criteria, with median age 64 years (57-72), and estimated baseline KPS 80 (80-90). Nineteen (47.5%) received LITT and 21 (42.5%) resections with intra-operative motor mapping. LITT patients trended towards smaller maximum diameters (2.1 cm vs 2.8 cm, p<0.01), with shorter ICU (0 vs 1 day, p<0.01) and hospital stays (1 vs. 2 days, p<0.01). At 30 days after treatment, 88.9% of resected patients had stable or improved symptoms compared to 35.3% of the LITT cohort (p<0.01). At 90 days, the difference was 87.5% to 50% (p=0.04), and at 180 days 100% to 85.7% (p=0.3684). When separated by new vs. progressive lesions, steroid responsiveness, and lesion histology, similar though not statistically significant trends were identified. In summary, LITT and resection provided similar functional outcomes in the treatment of lesions in or near the primary motor cortex for patients who survived at least 180 days post-treatment. Patients who received resection tended to have better functional outcomes in the nearer term. These differences are likely due to transient, expected post-LITT edema that subsides with time.

Zero Setup Margin Mask versus Frame Immobilization during Gamma Knife® Icon™ Stereotactic Radiosurgery for Brain Metastases.

Simple SummaryThe Gamma Knife® Icon™ allows for mask immobilization for stereotactic radiosurgery (SRS) as an alternative to frame immobilization. However, standardized recommendations for setup margins (SM) to create the planning target volume (PTV) with the mask immobilization do not exist and, therefore, practice patterns vary. Adding a SM might be the correct approach, if the possibility of significant intrafraction motion exists; on the other hand, it may be unnecessary as it increases the risk of radiation necrosis. This study, comprising 150 patients with 453 brain metastases (BM) treated for a median of 15 months of follow up, demonstrates that zero-SM mask immobilization had comparable clinical outcomes compared to a control group of similar patients undergoing frame immobilization SRS. There was no difference in freedom from local failure (FFLF) between the mask and frame immobilization groups on univariable or multivariable analysis. The initial findings support omitting a SM when using mask immobilization with this treatment approach on a GK Icon™.We compared the clinical outcomes of BM treated with mask immobilization with zero-SM (i.e., zero-PTV) to standard zero-SM frame immobilization SRS. Consecutive patients with BM, 0.5–2.0 cm in maximal diameter, treated with single-fraction SRS (22–24 Gy) during March 2019–February 2021 were included. Univariable and multivariable analysis were performed using the Kaplan–Meier method and Cox proportional hazards regression. A total of 150 patients with 453 BM met inclusion criteria. A total of 129 (28.5%) lesions were treated with a zero-SM mask immobilization and 324 (71.5%) with zero-SM frame immobilization. Frame immobilization treatments were associated with a higher proportion of gastrointestinal and fewer breast-cancer metastases (p = 0.024), and a higher number of treated lesions per SRS course (median 7 vs. 3; p < 0.001). With a median follow up of 15 months, there was no difference in FFLF between the mask and frame immobilization groups on univariable (p = 0.29) or multivariable analysis (p = 0.518). Actuarial FFLF at 1 year was 90.5% for mask and 92% for frame immobilization (p = 0.272). Radiation necrosis rates at 1 year were 12.5% for mask and 4.1% for frame immobilization (p = 0.502). For BM 0.5–2.0 cm in maximal diameter treated with single-fraction SRS using 22–24 Gy, mask immobilization with zero SM produces comparable clinical outcomes to frame immobilization. The initial findings support omitting a SM when using mask immobilization with this treatment approach on a Gamma Knife® Icon™.

Health related quality of life trajectories after stereotactic radiosurgery for brain metastases: a systematic review.

Health related quality of life (HRQoL) is often used as an outcome measure of cancer treatment. Stereotactic radiosurgery (SRS) is a mainstay treatment of brain metastases (BMs) with constantly improving treatment envelope. The goal of this systematic review was to evaluated HRQoL trajectories after SRS, identify important predictors of HRQoL after SRS, and to evaluate clinical importance of post-SRS HRQoL trajectories of BM patients treated with SRS. A systematic literature review according to the PRISMA guidelines analyzing HRQoL trajectories after SRS for BM published in the Pubmed/MEDLINE database before January, 2022. We identified 18 studies that evaluated HRQoL before and at least once after SRS for BMs. The majority of studies were single-institution retrospective series and included patients with different cancer types. Different instruments were used to assess HRQoL. In the majority of studies (n = 10) at group level, there was no significant change in global HRQoL after SRS. Stability, improvement, and deterioration of HRQoL global and subscale scores at individual patient level were common. Post-SRS HRQoL deterioration was predicted by worse functional status, greater number of BMs, delayed SRS, symptomatic BMs, and presence of seizures and cognitive impairment. Shorter post-SRS survival and adverse radiation effects (AREs) were associated with worse HRQoL. SRS for BMs is often associated with sustained preservation of HRQoL. Individual variation of HRQoL domains after SRS is common. Shorter survival and AREs are associated with worse HRQoL. Worse functional status and greater disease burden predict unfavorable HRQoL trajectories after SRS for BMs.

Using a fixed-jaw technique to achieve superior delivery accuracy and plan quality in single-isocenter multiple-target stereotactic radiosurgery for brain metastases

To quantify the influence of the minimum dynamic leaf gap (DLG) on delivery accuracy and plan quality and determine whether the fixed-jaw technique can be used to reduce the adverse effects of DLG in single-isocenter volumetric modulated arc therapy (VMAT) stereotactic radiosurgery (SRS) for multiple brain metastases (BMs). Twelve patients, each with two BMs, were enrolled in this study. For each patient, five simulated cases were generated by adjusting the intertarget distance (ITD; range, 1–5 cm). For each case, two single-isocenter VMAT SRS plans with and without the fixed-jaw technique were designed. For the plan without the fixed-jaw technique, the jaw positions were automatically set to cover two targets (AJ-VMAT). For the other plan, the jaw was fixed to cover one lesion when another lesion was irradiated (FJ-VMAT). Dosimetric parameters and delivery parameters of two plans were compared. FJ-VMAT plans achieved similar target conformity, lower dose spillages (V10%, V25%), and lower normal brain tissue (NBT) mean dose, and better gradient index than AJ-VMAT plans regardless of ITD but with more monitor units and longer beam-on time (P < 0.05). For ITD ≥2 cm, FJ-VMAT plans also yielded lower V50% and 12-Gy isodose volume for NBT compared to AJ-VMAT, and the reduction became more distinct as the ITD increased. In addition, FJ-VMAT generated a significantly higher gamma passing rate for each criterion (P < 0.05), especially for larger ITDs (≥2 cm) and tighter criteria (2%/1 mm) with a 4% improvement. Compared to conventional AJ-VMAT, FJ-VMAT could reduce the adverse effects from minimum DLG with superior delivery accuracy and plan quality in single-isocenter VMAT SRS for multiple BMs.

PO-1140 Survival after stereotactic radiosurgery for brain metastases – A single-institution experience

PO-1140 Survival after stereotactic radiosurgery for brain metastases – A single-institution experience

MO-0723 Outcomes and patterns of recurrence following stereotactic radiosurgery for brain metastases

MO-0723 Outcomes and patterns of recurrence following stereotactic radiosurgery for brain metastases

PO-1142 Clinical outcomes following Stereotactic Radiosurgery for Brain Metastases from Ovarian Carcinoma

PO-1142 Clinical outcomes following Stereotactic Radiosurgery for Brain Metastases from Ovarian Carcinoma

Commentary: Time to Steroid Independence After Laser Interstitial Thermal Therapy vs Medical Management for Treatment of Biopsy-Proven Radiation Necrosis Secondary to Stereotactic Radiosurgery for Brain Metastasis.

Commentary: Time to Steroid Independence After Laser Interstitial Thermal Therapy vs Medical Management for Treatment of Biopsy-Proven Radiation Necrosis Secondary to Stereotactic Radiosurgery for Brain Metastasis.

Commentary: From Postoperative to Preoperative: A Case Series of Hypofractionated and Single-Fraction Neoadjuvant Stereotactic Radiosurgery for Brain Metastases.

Commentary: From Postoperative to Preoperative: A Case Series of Hypofractionated and Single-Fraction Neoadjuvant Stereotactic Radiosurgery for Brain Metastases.

Time to Steroid Independence After Laser Interstitial Thermal Therapy vs Medical Management for Treatment of Biopsy-Proven Radiation Necrosis Secondary to Stereotactic Radiosurgery for Brain Metastasis.

Radiation necrosis (RN) after stereotactic radiosurgery (SRS) for brain metastases (BM) can result in significant morbidity, compounded by the effects of extended steroid therapy. Laser interstitial thermal therapy (LITT) is a minimally invasive procedure that can offer definitive treatment for RN while potentially obviating the need for prolonged steroid use. To compare LITT vs medical management (MM) in the treatment of RN. A multicenter, retrospective study was performed of SRS-treated patients with BM who developed biopsy-proven RN and were treated with LITT or MM. Clinical outcome data were compared by treatment modality. Seventy-two patients met criteria with a median follow-up of 10.0 months (4.2-25.1), and 57 patients (79%) underwent LITT. Four MM (27%) and 3 LITT patients (5%) demonstrated radiographic progression (P = .031) at a median of 5.3 and 4.0 months (P = .40). There was no significant difference in overall survival (LITT median of 15.2 vs 11.6 months, P = .60) or freedom from local progression (13.6 vs 7.06 months, P = .40). Patients stopped steroid therapy earlier in the LITT cohort at a median of 37 days compared with 245 days (P < .001). When controlled for follow-up duration, patients treated with LITT were 3 times more likely to be weaned off steroids before the study end point (P = .003). These data suggest that LITT for treatment of biopsy-proven RN after SRS for BM significantly decreases time to steroid independence. Prospective trials should be designed to further validate the utility of LITT for RN and its impact on steroid-induced morbidity.

How Useful are 3-monthly MRI Surveillance Scans after Stereotactic Radiosurgery for Brain Metastases? A Single Institution Experience

An estimated 20-40% of patients diagnosed with a primary cancer will develop brain metastases during the course of their disease [1]. This number is increasing due to the development of novel systemic therapies that improve patient survival.