Advances in breast cancer treatment: a systematic review of preoperative stereotactic body radiotherapy (SBRT) for breast cancer.

Breast conserving treatment typically involves surgical excision of tumor and adjuvant radiotherapy targeting the breast area or tumor bed. Accurately defining the tumor bed is challenging and lead to irradiation of greater volume of healthy tissues. Preoperative stereotactic body radiotherapy (SBRT) which target tumor may solves that issues. We conducted a systematic literature review to evaluates the early toxicity and cosmetic outcomes of this promising treatment approach. Secondary we reviewed pathological complete response (pCR) rates, late toxicity, patient selection criteria and radiotherapy protocols. We retrieved literature from PubMed, Scopus, Web of Science, Cochrane, ScienceDirect, and ClinicalTrials.gov. The study adhered to the PRISMA 2020 guidelines. Ten prospective clinical trials (7 phase II, 3 phase I), encompassing 188 patients (aged 18-75 years, cT1-T3 cN0-N3 cM0, primarily with ER/PgR-positive, HER2-negative status,), were analyzed. Median follow-up was 15 months (range 3-30). Treatment involved single-fraction SBRT (15-21Gy) in five studies and fractionated (19.5-31.5Gy in 3 fractions) in the rest. Time interval from SBRT to surgery was 9.5 weeks (range 1-28). Acute and late G2 toxicity occurred in 0-17% and 0-19% of patients, respectively, G3 toxicity was rarely observed. The cosmetic outcome was excellent in 85-100%, fair in 0-10% and poor in only 1 patient. pCR varied, showing higher rates (up to 42%) with longer intervals between SBRT and surgery and when combined with neoadjuvant systemic therapy (up to 90%). Preoperative SBRT significantly reduce overall treatment time, enabling to minimalize volumes. Early results indicate excellent cosmetic effects and low toxicity.

Long-term complications and outcomes of therapeutic embolization of cerebral arteriovenous malformations: a systematic review.

BACKGROUND: Embolization is a promising treatment strategy for cerebral arteriovenous malformations (AVMs). However, consensus regarding the main complications or long-term outcomes of embolization in AVMs remains lacking. OBJECTIVE: To characterize the most prevalent complications and long-term outcomes in patients with AVM undergoing therapeutic embolization. DESIGN AND SETTING: This systematic review was conducted at the Federal University of Alagoas, Arapiraca, Brazil. METHODS: This systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses criteria. Data were obtained from MEDLINE, PubMed, LILACS, and SciELO databases, which included the epidemiological profile of the population, characteristics of the proposed therapy, complications (hemorrhagic events and neurological deficits), and long-term outcomes (modified Rankin scale pre- and post-treatment, AVM recanalization, complete obliteration, and deaths). RESULTS: Overall, the analysis included 34 articles (2,799 patients). Grade III Spetzler-Martin AVMs were observed in 34.2% of cases. Notably, 39.3% of patients underwent embolization combined with radiosurgery. The most frequently reported long-term complication was hemorrhage, which occurred in 8.7% of patients at a mean follow-up period of 58.6 months. Further, 6.3% of patients exhibited neurological deficits after an average of 34.7 months. Complete obliteration was achieved in 51.4% of the cases after a mean period of 36 months. Recanalization of AVMs was observed in 3.5% of patients. Long-term death occurred in 4.0% of patients. CONCLUSION: Embolization of AVMs is an increasingly safe strategy with low long-term complications and satisfactory outcomes, especially in patients who have undergone combination therapies. SYSTEMATIC REVIEW REGISTRATION: https://www.crd.york.ac.uk/prospero/ Registration number CRD42020204867.

Quality of life and patient-reported toxicities in patients with advanced Merkel cell carcinoma treated with combined nivolumab and ipilimumab with or without stereotactic body radiation therapy.

BACKGROUND: Merkel cell carcinoma is a rare skin cancer associated with poor survival. Based on a previous Phase II trial of adults with advanced Merkel cell carcinoma by Kim and colleagues (2022), there is now a strong rationale for combination therapy (i.e., nivolumab and ipilimumab) to become a treatment option for patients with advanced Merkel cell carcinoma. The goal of this paper was to report on the secondary outcome of quality of life (QOL) among patients on this trial. METHODS: Patients receiving combined nivolumab and ipilimumab, with or without stereotactic body radiation therapy (SBRT), completed the European Organisation for Research and Treatment of Cancer (EORTC) QLQ-C30 prior to starting treatment and every 2 weeks thereafter. Changes in QOL during treatment and post-treatment were evaluated using piecewise random-effects mixed models. Exploratory analyses compared changes in QOL between study arms. The original trial was registered with ClinicalTrials.gov (NCT03071406). RESULTS: Study participants (n = 50) reported no changes in overall QOL (ps > 0.05), but emotional functioning improved during treatment (p = 0.01). Cognitive and social functioning worsened post-treatment (ps < 0.01). In general, patients treated with combination therapy only (n = 25) reported no change in QOL over time, whereas patients also treated with SBRT (n = 25) consistently demonstrated worsening QOL post-treatment. CONCLUSION: QOL is generally preserved in patients treated with combination therapy, but the addition of SBRT may worsen QOL. Combined with clinical efficacy data published previously, results support the use of combination therapy with nivolumab and ipilimumab as a treatment option for patients with advanced Merkel cell carcinoma.

Stereotactic Body Radiation Therapy (SBRT) in prostate cancer in the presence of hip prosthesis - is it a contraindication? A narrative review.

Hip replacement is a common orthopedic surgery in the aging population. With the rising incidence of prostate cancer, metallic hip prosthetics can cause considerable beam hardening and streak artifacts, leading to difficulty in identifying the target volumes and planning process for radiation treatment. The growing use of Stereotactic Body Radiation Therapy (SBRT) to treat prostate cancer is now well established. However, the use of this treatment modality in the presence of a hip prosthesis is poorly understood. There is enough literature on planning for external beam radiation treatment without any difficulties in the presence of hip prosthesis with conventional or Hypofractionated treatment. However, there is a shortage of literature on the impact of the prosthesis in SBRT planning, and there is a need for further understanding and measures to mitigate the obstacles in planning for SBRT in the presence of hip prosthesis. We present our review of the intricacies that need to be understood while considering SBRT in the presence of hip prostheses in prostate cancer treatment.

Celiac plexus radiosurgery for pain management in advanced cancer: a multicentre, single-arm, phase 2 trial.

BACKGROUND: Refractory upper abdominal pain or lower back pain (retroperitoneal pain syndrome) related to celiac plexus involvement characterises pancreatic and other upper gastrointestinal malignancies and is an unmet need. We hypothesised that ablative radiation delivered to the celiac plexus would decrease pain. METHODS: This multicentre, single-arm, phase 2 study was done at eight hospitals in five countries (Israel, Poland, Canada, the USA, and Portugal). Eligible patients aged 18 years or older with an average pain level of 5-10 on the Brief Pain Inventory short form (BPI-SF), an Eastern Cooperative Oncology Group performance status score of 0-2, and either pancreatic cancer or other tumours involving the celiac axis, received a single fraction of 25 Gy of external-beam photons to the celiac plexus. The primary endpoint was complete or partial pain response based on a reduction of the BPI-SF average pain score of 2 points or more from baseline to 3 weeks after treatment. All evaluable patients with stable pain scores were included in response assessment. The trial is registered with ClinicalTrials.gov, NCT03323489, and is complete. FINDINGS: Between Jan 3, 2018, and Dec 28, 2021, 125 patients were treated, 90 of whom were evaluable. Patients were followed up until death. Median age was 65·5 years (IQR 58·3-71·8), 50 (56%) were female and 40 (44%) were male, 83 (92%) had pancreatic cancer, and 77 (86%) had metastatic disease. Median baseline BPI-SF average pain score was 6 (IQR 5-7). Of the 90 evaluable patients at 3 weeks, 48 (53%; 95% CI 42-64) had at least a partial pain response. The most common grade 3-4 adverse events, irrespective of attribution, were abdominal pain (35 [28%] of 125) and fatigue (23 [18%]). 11 serious adverse events of grade 3 or worse were recorded. Two grade 3 serious adverse events were probably attributed to treatment by the local investigators (abdominal pain [n=1] and nausea [n=1]), and nine were possibly attributed to treatment (seven were grade 3: blood bilirubin increased [n=1], duodenal haemorrhage [n=2], abdominal pain [n=2], and progressive disease [n=2]; and two were grade 5: gastrointestinal bleed from suspected varices 24 days after treatment [n=1] and progressive disease [advanced pancreatic cancer] 89 days after treatment [n=1]). INTERPRETATION: Celiac plexus radiosurgery could potentially be a non-invasive palliative option for patients with retroperitoneal pain syndrome. Further investigation by means of a randomised comparison with conventional celiac block or neurolysis is warranted. FUNDING: Gateway for Cancer Research and the Israel Cancer Association.

Clinical and radiological effects of Bevacizumab for the treatment of radionecrosis after stereotactic brain radiotherapy.

PURPOSE: The purpose of this multicenter retrospective study was to analyze the clinical and radiological effects of bevacizumab (BV) on radionecrosis (RN) that developed after stereotactic radiotherapy (SRT) for brain metastasis. METHODS: Forty patients with SRT related symptomatic brain RN treated in 10 radiation oncology centers were analyzed. The clinical response to BV treatment was categorized as follows: complete (no additional treatment required), partial (requiring either steroids or repeat BV), and unresponsive (requiring surgery). The radiological features of brain RN were analyzed in 10 patients whose serial MRI scans were available after corticosteroid and BV treatments. RESULTS: BV was used as a first line treatment in 11 (27.5%) and as a second line treatment in 29 (72.5%) of patients. The neurological symptoms regressed in 77.5% of patients after treatment with BV (45% complete response, 32.5% partial response). The median edema volume increased from 75.9 cc (range: 5.9-125.8 cc) at RN to 113.65 cc (range: 1.5-382.1 cc) after use of corticosteroids, representing a rate of 39.8% increase (p = 0.074). However, after BV treatment the median volume of edema decreased to 19.5 cc (range: 0-163.3 cc) which represents a difference of 62.2% (p = 0.041) from RN. CONCLUSION: The use of BV caused clinical response rate of 77.5% and a good radiological response in corticosteroid unresponsive patients. The role of BV should be further investigated in prospective studies.

Stereotactic Body Radiotherapy for Oligoprogression in Castration-Resistant Prostate Cancer: Early Toxicity Analysis of the TRAP Trial.

AIMS: To assess toxicity and patient quality of life after stereotactic body radiotherapy (SBRT) to oligoprogressive disease (OPD) in patients with metastatic castrate-resistant prostate cancer (CRPC) on androgen receptor targeted agents (ARTA). MATERIAL AND METHODS: This phase II trial enrolled patients with metastatic CRPC with ≤ 2 oligoprogressive lesions in bone, lymph node, lung, or prostate. All patients were receiving systemic treatment with abiraterone or enzalutamide at the time of oligoprogression. All patients received SBRT to the OPD site(s) and continued the current ARTA. Patients received 30 Gy in 5 fractions (alternate days) to the OPD site. The primary endpoint of the trial is to assess if SBRT to OPD sites results in progression free survival of >6 months. The primary endpoint for this toxicity analysis is the rate of grade 3 or higher adverse events at any timepoint up to 6 months after SBRT. Secondary endpoints included comparing pre- and post-SBRT patient-related outcomes reported using visual analogue scale scores and EQ-5D health questionnaire. RESULTS: Forty enrolled patients had at least 6 months of follow-up at the time of analysis. Grade 3 or higher toxicity from any cause recorded using common terminology criteria for adverse events and radiation therapy oncology group was found in 8/40 (20%) of patients, but only 1/40 (2.5%) was deemed possibly related to SBRT. There was no significant difference in mean EQ5D visual analogue scale score from baseline to each timepoint after SBRT (p = 0.449). CONCLUSION: In this prospective phase II clinical trial for OPD whilst on ARTA in the CRPC setting, we report low grade ≥ 3 toxicity after SBRT. There is no discernible change in patient-reported quality of life due to SBRT treatment. The final results of progression-free survival and toxicity of SBRT treatment will be reported once further follow-up is complete.

Gamma Knife radiosurgery for multiple sclerosis-associated trigeminal neuralgia.

BACKGROUND: Gamma Knife radiosurgery (GKRS) has well-known efficacy in the treatment of idiopathic trigeminal neuralgia (TN). However, few studies have evaluated the effects of GKRS in the treatment of multiple sclerosis (MS)-related TN. This study analyzed the efficacy and complications of GKRS for MS-related TN. METHODS: This retrospective study included 28 MS-related TN patients who underwent GKRS with a median follow-up of 27 (range, 12-181) months. The cisternal segment of the trigeminal nerve was targeted with a median radiation dose of 80 (80-90) Gy. Pain intensity was assessed using Barrow Neurological Institute (BNI)-Pain Intensity Scores (BNI-PIS). Before GKRS, all patients suffered from BNI pain levels of 4 or 5. A reduction in pain to BNI 3b or below was deemed as adequate pain relief. RESULTS: The initial proportion of patients who experienced adequate pain relief was 71.4%, with a median interval of 21 (1-45) days. At the final follow-up, 50% of patients had achieved adequate pain relief. Ten patients (35.7%) suffered from complications, including four with facial sensorial dysfunctions, four with a decline in their corneal reflexes, and two with jaw weakness. Among the 20 initial responders, six (30%) patients suffered pain recurrence after a median interval of 35 (12-180) months. CONCLUSIONS: GKRS is an effective means of pain relief in MS-related TN, but has side effects that are relevant to other ablative treatments. The benefits and risks of GKRS should be discussed with patients who wish to avoid surgery or when previous treatments fail.

Severe pneumocranium after gamma knife stereotactic radiosurgery for brain metastasis: A case report and literature review.

RATIONALE: Gamma knife stereotactic radiosurgery (GKRS) is a recognized safe and effective treatment for brain metastasis; however, some complications can present significant clinical challenges. This case report highlights a rare occurrence of cerebrospinal fluid (CSF) leakage and pneumocranium following GKRS, emphasizing the need for awareness and prompt management of these complications. PATIENT CONCERNS: A 35-year-old male with a history of malignant neoplasm of the lip in 2015 and perineural spread of malignancy into the left cavernous sinus was treated with GKRS in 2017. The patient was admitted emergently 39 days after discharge due to persistent headache and dizziness. DIAGNOSES: Brain computed tomography (CT) revealed diffuse bilateral pneumocranium alongside an observation of CSF leakage. INTERVENTIONS: A surgical procedure involving a left frontal-temporal craniotomy was performed to excise a residual skull base tumor and repair the dura, guided by a navigator system. The conclusive pathological assessment revealed the presence of squamous cell carcinoma markers. OUTCOMES: The patient exhibited excellent tolerance to the entire procedure and experienced a prompt and uneventful recovery process. After surgery, the symptoms alleviated and CSF leak stopped. The follow-up image showed the pneumocranium resolved. LESSONS: Pneumocranium due to early-stage post-GKRS is uncommon. The rapid tumor shrinkage and timing of brain metastasis spreading through the dura can lead to CSF leak and pneumocranium. We reviewed current treatment options and presented a successful craniotomy-based dura repair case.

Stereotactic Body Radiotherapy Reirradiation Is Safe in Patients With Lung Cancer With In-Field Enlarged Tumor Recurrence.

Introduction: Recurrence after stage III lung cancer treatment usually appears with a poor prognosis, and salvage therapy for these patients is challenging, with limited data for reirradiation. Materials and Methods: Fifteen patients with recurrent stage III lung cancer treated with stereotactic body radiotherapy (SABR) between October 2013 and December 2017 were retrospectively evaluated for local control as a first endpoint; overall survival, disease-free survival, and treatment-related toxicity were secondary endpoints. Results: The median age was 68 (IQR: 50-71) years, and the median tumor size was 3.3 cm (IQR: 3.0-4.5). The radiation field was all within the previous radiation (previous 80%-90% isodose line), and the median dose was 66 Gy/(2 Gy × 33 standard fractionation). For SABR, the median biologically effective dose at an α/ß ratio of 10 (BED10) was 60.0 Gy (IQR: 39.38-85.0) and given in 3 to 5 fractions. Three patients experienced grade 3 or 4 toxicity but none experienced grade 5. The median follow-up period was 14 (IQR: 10-23) months. The local control rate was found as 86.7% in the first year, 80% in the second year, and 80% in the third year. The median disease-free survival was 8 (IQR: 6-20) months and the median overall survival was 14 (IQR: 10-23) months. The rate of overall survival was 66.6% for the first year and 33.3% for the second and third years. The disease-free survival rate was 46.6% for the first year and 40% for the second and third years. Nine patients who received doses of BED10 ≥ 50 Gy developed no local recurrence (P = .044). Discussion: In local local-regional recurrence of lung cancer, radiosurgery as reirradiation can be used at doses of BED10 ≥ 50 Gy and above to provide local control for radical or palliative purposes. SABR is an important and relatively safe treatment option in such recurrences.

Stereotactic body radiation therapy for primary renal cell carcinoma: A review on behalf of the CC-AFU.

INTRODUCTION: The incidence of localized renal cell carcinoma (RCC) is on the rise among individuals aged 70 and older. While the gold standard for treatment remains surgical resection, some elderly and frail patients with comorbidities are not eligible for this procedure. In selected cases, percutaneous thermal ablation, such as cryotherapy, microwave and radiofrequency, offers less invasive options. General anesthesia is sometimes necessary for such treatments, but most of the procedures can be conducted using mild or deep conscious sedation. This approach is preferably recommended for small cT1a tumors situated at a distance from the renal hilum and/or ureter. Active surveillance remains an alternative in the case of small low grade RCC although it may induce anxiety in certain patients. Recent research has highlighted the potentials of stereotactic ablative body radiotherapy (SABR) as a noninvasive, well-tolerated, and effective treatment for small renal tumors. This narrative review aims to explore recent advances in SABR for localized RCC, including appropriate patient selection, treatment modalities and administration, as well as efficacy and tolerance assessment. MATERIAL AND METHODS: We conducted a literature review using the terms [kidney cancer], [renal cell carcinoma], [stereotactic radiotherapy], [SBRT], and [SABR] in the Medline, PubMed, and Embase databases, focusing on prospective and relevant retrospective studies published in English. RESULTS: Studies report local control rates ranging from 70% to 100% with SABR, highlighting its efficacy in treating RCC. The decline in glomerular filtration rate (GFR) is approximately -5 to -17mL/min over the years following SABR. Common toxicities are rare, primarily CTCAE grade 1, include fatigue, nausea, chest or back pain, diarrhea, or gastritis. CONCLUSION: Stereotactic ablative body radiotherapy (SABR) may be considered as a viable option for patients with localized RCC who are not suitable candidates for surgery with a high local control rate and a favorable safety profile. This approach should be discussed in a multidisciplinary meeting and results from ongoing clinical trials are awaited.

Efficacy and safety of SBRT combined with sintilimab and IBI305 in patients with advanced HCC and previously failed immunotherapy: study protocol of a phase 2 clinical trial.

INTRODUCTION: Hepatocellular carcinoma (HCC) is a leading cause of cancer-related death in China. The combination of immune checkpoint inhibitors (ICIs) and antiangiogenic drugs, such as bevacizumab and tyrosine kinase inhibitors, has been recommended as first-line treatment for advanced HCC. However, two-thirds of patients did not benefit from this form of immunotherapy. Currently, data on the subsequent regimen for patients previously treated with ICIs are lacking. Studies have shown that the combination of radiotherapy (RT) and ICIs is a potentially effective second-line therapy for HCC. This study aims to assess the efficacy and safety of combined therapy with stereotactic body RT (SBRT), sintilimab and IBI305 (a biosimilar of bevacizumab) in patients with HCC following the progression of first-line ICI therapy. METHODS AND ANALYSIS: This study is an open-label, single-arm, single-centre, phase 2 trial of 21 patients with advanced HCC in whom previous ICI therapy has failed. Participants will receive approximately 30-40 Gy/5-8F SBRT, followed by 200 mg sintilimab and 15 mg/kg IBI305 intravenously every 3 weeks. Treatment will continue until the development of unacceptable toxicity or disease progression. We will use Simon's two-stage design, with the objective response rate (ORR) as the primary endpoint. Secondary endpoints include ORR of lesions without RT, disease control rate, progression-free survival, overall survival and safety. ETHICS AND DISSEMINATION: The study was authorised by the Medical Ethics Committee. Dissemination of results will occur via a peer-reviewed publication and other relevant media. TRIAL REGISTRATION NUMBER: ChiCTR2200056068.

Myonecrosis as a rare side effect of stereotactic body radiotherapy for bone metastases: Report of two cases and a comprehensive literature review.

Stereotactic body radiotherapy is a highly effective form of radiation therapy for palliation of bone metastases, but it can also lead to rare but severe side effects, such as myonecrosis. According to the literature, the incidence of myonecrosis after stereotactic body radiotherapy is low and mostly dose dependent. It is crucial to consider the potential impact of immunotherapy and other systemic therapies in the assessment. The course of radiation myonecrosis can vary, and corticosteroids or vascular endothelial growth factor inhibitors may potentially play a role in its treatment. Herein, we report two patients presenting with myonecrosis after stereotactic body radiotherapy for bone metastasis.

Radiation Maculopathy in Patients with Malignant Melanoma of the Corpus Ciliare and Choroidea Following One-Day Session of Stereotactic Radiosurgery.

The aim of the thesis is to present the case of a patient in whom bilateral calcification of the hydrophilic intraocular lens (IOL) Lentis M+ LS-313 MF30 (Oculentis) has developed. Due to the negative effect on visual functions, explantation and replacement of the artificial lens was necessary in both eyes. Case Report: An overview of the available literature summarized the diagnostics, current examination methods and possibilities of the surgical solution of calcification of the bifocal hydrophilic lens Lentis M+ LS-313 MF30 (Oculentis). The specific solution is described in a case report of a patient in whom calcification of both lenses developed 6 years after implantation of the IOL. In 2015, the patient underwent uncomplicated cataract surgery of both eyes with the implantation of an artificial intraocular lens into the capsule. In September 2021, an 82-year-old man was examined at our outpatient clinic for deterioration of visual acuity and changes in the material of the artificial IOL which were perceptible during a clinical examination, on the recommendation of a local ophthalmologist. Blurred vision predominated. A diagnosis of intraocular lens opacification was confirmed and documented using a Scheimpflug camera (OCULUS Pentacam HR) and anterior OCT (Avanti RTVue XR Optovue,). The patient was indicated for explantation and replacement of the opacified intraocular lens in the left and subsequently in the right eye- The same type of IOL was used for reimplantation with good functional results. Conclusion: Since 2010, multifocal lens implantation has been on an upward trend worldwide. This type of MF IOL has also been used in thousands of implantations. A number of other explantations can be expected in the coming years. The optimal solution is the correct replacement of the calcified IOL with the same construction made of safer hydrophobic material.

Radiation-Induced DNA Damage in Uveal Melanoma Is Influenced by Dose Delivery and Chromosome 3 Status.

Purpose: The purpose of this study was to analyze the extent of DNA breaks in primary uveal melanoma (UM) with regard to radiotherapy dose delivery (single-dose versus fractionated) and monosomy 3 status. Methods: A total of 54 patients with UM were included. Stereotactic radiotherapy (SRT) was performed in 23 patients, with 8 undergoing single-dose SRT (sdSRT) treatment and 15 receiving fractionated SRT (fSRT). DNA breaks in the enucleated or endoresected tumors were visualized by a TUNEL assay and quantified by measuring the TUNEL-positive area. Protein expression was analyzed by immunohistochemistry. Co-detection of chromosome 3 with proteins was performed by immuno-fluorescent in situ hybridization. Results: The amount of DNA breaks in the total irradiated group was increased by 2.7-fold (P < 0.001) compared to non-irradiated tissue. Tumors treated with fSRT were affected more severely, showing 2.1-fold more DNA damage (P = 0.007) compared to the cases after single (high) dose irradiation (sdSRT). Monosomy 3 tumors showed less DNA breaks compared to disomy 3 samples (P = 0.004). The presence of metastases after radiotherapy correlated with monosomy 3 and less DNA breaks compared to patients with non-metastatic cancer in the combined group with fSRT and sdSRT (P < 0.05). Conclusions: Fractionated irradiation led to more DNA damage than single-dose treatment in primary UM. As tumors with monosomy 3 showed less DNA breaks than those with disomy 3, this may indicate that they are less radiosensitive, which may influence the efficacy of irradiation.

The incidence and predictive factors of secondary epilepsy in patients with supratentorial brain metastases (st-BMs) after stereotactic radiosurgery: A multicenter retrospective study.

OBJECTIVE: To evaluate the incidence and the independent risk factors of SRS-related epilepsy in patients with supratentorial brain metastases (st-BMs), providing evidences for prevention or reduction secondary epilepsy after SRS. METHODS: Patients with st-BMs from four gamma knife centers who developed secondary epilepsy after SRS were retrospectively studied between January 1, 2017 and June 31, 2023. The incidence and clinical characteristics of the patients with secondary epilepsy were analyzed. The predictive role of baseline clinical-demographic variables was evaluated according to univariate and multivariate logistic regression model. The impact of secondary epilepsy on patients' OS was evaluated as well by log-rank test. RESULTS: 11.3 % (126/1120) of the patients with totally 158 st-BMs experienced secondary epilepsy after SRS in median 21 days. 61.9 % (78/126) of the patients experienced simple partial seizures. 91.3 % (115/126) patients achieved good seizure control after received 1-2 kinds of AEDs for median 90 days, while 7.1 % (9/126) of the patients suffered from refractory epilepsy. Patients had higher risk of secondary epilepsy if the tumor located in cortex and/or hippocampus, peri-tumor edema larger than 20.3 cm3 before SRS, had epilepsy history, and failed to receive bevacizumab prior to SRS. There was no difference in the OS of patients who experience secondary epilepsy or not after SRS. CONCLUSIONS: The incidence of SRS-related secondary epilepsy is 11.3 % in patients with st-BMs in this retrospective study. The risk of secondary epilepsy is higher in patients with st-BM located in cortex and/or hippocampus area, peri-tumor edema larger than 20.3 cm3 before SRS, and epilepsy history. Bevacizumab is suggested prior to SRS therapy, as it could be used for the control of peri-tumor edema and SRS-related damage, hence reduce the risk of secondary epilepsy. However, whether or not patients suffered from secondary epilepsy after SRS does not affect their OS.