Focal radiation necrosis of the brain (fRNB) is a late adverse event that can occur following the treatment of benign or malignant brain lesions with stereotactic radiation therapy (SRT) or stereotactic radiosurgery (SRS). Recent studies have shown that the incidence of fRNB is higher in cancer patients who received immune checkpoint inhibitors. The use of bevacizumab (BEV), a monoclonal antibody that targets the vascular endothelial growth factor (VEGF), is an effective treatment for fRNB when given at a dose of 5–7.5 mg/kg every two weeks. In this single-center retrospective case series, we investigated the effectiveness of a low-dose regimen of BEV (400 mg loading dose followed by 100 mg every 4 weeks) in patients diagnosed with fRNB. A total of 13 patients were included in the study; twelve of them experienced improvement in their existing clinical symptoms, and all patients had a decrease in the volume of edema on MRI scans. No clinically significant treatment-related adverse effects were observed. Our preliminary findings suggest that this fixed low-dose regimen of BEV can be a well-tolerated and cost-effective alternative treatment option for patients diagnosed with fRNB, and it is deserving of further investigation.

We studied the dose–local control (LC) relationship in ablative vs. non-ablative radiotherapy in a non-radical treatment setting of “locally advanced pancreatic cancer (LAPC)” by comparing our patients (n = 89) treated with SBRT on the CyberKnife unit vs. conventional radiation between January 2005 and January 2021, and by reviewing the literature. A systematic search was performed leveraging Medline for references on SBRT use in pancreatic cancer without date terms or language restrictions. A total of 3702 references were identified and the search was then repeated in Embase and the Cochrane database. Ultimately, 12 studies were eligible for inclusion, which either compared SBRT to conventional radiation, or SBRT use in dose escalation for primary LAPC in a non-neoadjuvant setting. Our cohort’s median overall survival was 152 days (CI 95%, 118–185); including 371 days (CI 95%, 230–511) vs. 126 days (CI 95%, 90–161) favoring SBRT, p = 0.004. The median time to local progression was 170 days (48–923) for SBRT vs. 107 days (27–489) for the non-ablative group. In our SBRT patients, no local progressions were seen with BED₁₀ > 60 Gy. Even when palliating LAPC, SBRT should be considered as an alternative to conventional radiation, especially in patients with a low disease burden. BED₁₀ ≥ 60–70 Gy offers better local control without increasing toxicity rates. Less local progression may provide a better quality of life to those patients who already have a short life expectancy.

Background: Subependymal giant cell astrocytoma is a benign brain tumor that occurs in patients with tuberous sclerosis complex. Surgical removal is the traditional treatment, and expert opinion is strongly against the use of radiotherapy. Recently, success has been reported with the mTor inhibitor everolimus in reducing tumor volume, but regrowth has been observed after dose reduction or cessation. Case report: We present the case of a 40-year-old Asian female patient treated successfully for growing bilateral subependymal giant cell astrocytoma with fractionated stereotactic radiotherapy before everolimus became available. After a follow-up of 8 years, everolimus was administered for renal angiomyolipoma and the patient was followed up until 13 years after radiotherapy. Successive magnetic resonance imaging demonstrated an 80% volume reduction after radiotherapy that increased to 90% with everolimus. A review of the literature was done leveraging Medline via PubMed, and we assembled a database of 1298 article references and 780 full-text articles in search of evidence for contraindicating radiotherapy in subependymal giant cell astrocytoma. Varying results of single-fraction radiosurgery were described in a total of 13 cases. Only in two published cases was the radiation dose of fractionated radiotherapy mentioned. One single publication mentions an induced secondary brain tumor 8 years after whole-brain radiotherapy. Conclusion: There is no evidence of contraindication and exclusion of fractionated radiotherapy in treating subependymal giant cell astrocytoma. Our experience demonstrates that subependymal giant cell astrocytoma, as other benign intracranial tumors, responds slowly but progressively to radiotherapy and suggests that fractionated stereotactic radiotherapy holds promise to consolidate responses obtained with mTor inhibitors avoiding regrowth after cessation.

Background: Stereotactic body radiotherapy (SBRT) for pancreatic cancer is limited by the proximity of tumors to gastrointestinal (GI) organs, increasing the risk of toxicity. Magnetic resonance‐guided radiotherapy (MRgRT) offers potential advantages through superior soft tissue visualization, real‐time tumor tracking, and online adaptive planning. This study aimed to quantitatively compare dosimetric outcomes of pancreatic cancer SBRT using online adaptive MRgRT versus conventional computed tomography‐based image‐guided radiotherapy (CT‐IGRT). Methods: A retrospective dosimetric analysis was conducted on 100 plans from 10 patients with primary ( n = 3) or recurrent ( n = 7) pancreatic adenocarcinoma treated between July 2021 and December 2022 at UZ Brussel. Treatment included 80 adaptive MRgRT fractions, 10 initial MR plans, and 10 CT‐based volumetric‐modulated arc therapy (VMAT) plans using an internal target volume (ITV) approach. All patients were treated on the MRIdian system with daily online adaptation and real‐time beam gating. Dosimetric endpoints included target coverage, plan quality metrics, and organ‐at‐risk (OAR) doses. Statistical comparisons were performed using Wilcoxon signed‐rank tests. Results: MRgRT significantly reduced target volumes compared to CT‐IGRT (median gross tumor volume (GTV): 40.65 cc vs. 62.56 cc; p = 0.005; median planning target volume (PTV): 64.4 cc vs. 94.4 cc; p = 0.005) and improved dose coverage of both GTV and PTV. Intermediate dose spillage (R50%) was also lower with MRgRT (5.18 vs. 6.56, p = 0.04). MRgRT plans provided superior sparing of critical GI OARs, with median D _5cc relative dose reductions of 42% to the small bowel ( p = 0.02), 23% to the duodenum ( p = 0.02), and 13% to the stomach ( p = 0.01). No significant differences were observed for the liver, kidneys, or large bowel. Treatment was well tolerated, with only grade I–II toxicities reported. Conclusions: MR‐guided adaptive SBRT demonstrated dosimetric superiority over CT‐IGRT in pancreatic cancer, with improved target coverage and enhanced GI OAR sparing. These findings support the use of MRgRT to expand the therapeutic window for safe dose escalation. Prospective studies are warranted to confirm clinical benefits.

Background Subependymal giant cell astrocytoma is a deep-seated benign but life-threatening brain tumor that occurs in patients with the tuberous sclerosis complex. Resection is the traditional treatment and expert opinion is strongly against the use of radiotherapy. Systematic epidemiological studies, however, demonstrate high rates of complications and recurrences. The need for efficient non-surgical treatment is best illustrated by the considerable enthusiasm about the activity of the mTOR inhibitor everolimus in reducing tumor volume. Unfortunately regrowth is frequent after dose reduction or cessation and continued tumor control requires continued administration of the drug, leading to concerns about its metabolic and immunosuppressive side effects and cost of treatment. Results We successfully treated a case with growing bilateral subependymal giant cell astrocytoma with fractionated stereotactic radiotherapy before everolimus became available. After a follow-up of 8 years, everolimus was administered for renal angiomyolipoma and the patient was followed up until 13 years after radiotherapy. Successive MRI's demonstrated an 80% volume reduction after radiotherapy that further increased to 90% during everolimus administration. In order to review the basis for the strong expert opinion against radiotherapy, we performed an exhaustive literature study regarding efficiency, potential dangers and side effects of radiation. 1298 article references and 780 full-text articles in search of evidence for contra-indicating radiotherapy. Varying short-term tumor control of single-fraction radiosurgery were described in a total of 13 cases. Only in two published cases the radiation dose of fractionated radiotherapy was mentioned. A single publication mentions an induced secondary brain tumor 8 years after total brain irradiation. Conclusion There is no evidence for contra-indicating fractionated radiotherapy in subependymal giant cell astrocytoma. Our experience demonstrates that these tumors, as other benign intracranial tumors, responds slowly to radiotherapy and suggests that fractionated stereotactic radiotherapy holds promise to consolidate responses obtained with mTOR inhibitors avoiding regrowth after cessation. This combined treatment would avoid costs and complications of long-term treatment with everolimus and deserves to be studied as a definitive non-surgical treatment.

We studied the use of palliative radiotherapy (RT) among patients with primary, non-curable, locally advanced pancreatic cancer. In this subset of patients, with very poor survival, various palliative RT dose fractionation schemes are used; but, in the absence of a guideline, practice patterns vary, and dose choice is mainly based on the physician’s intuition. We divided the patients into three groups, according to the dose fractionation schedules received: low (A), intermediate (B), and high (C) dose groups, to study the potential differences in outcome between the different dose prescriptions. Cohort: n = 184. Median age: 69 years. Male: n = 105 (57%), female: n = 79 (43%). Stage IV: n = 117 (64%). T4: n = 127 (69%). Tumor location: head: n = 109 (59%), body: n = 37 (20%), tail: n = 25 (14%), neck: n = 11 (6%), and uncinate: n = 2 (1%). Prior systemic therapy: n = 66 (36%). Most common dose fractionations received: 20 Gy in five fractions n = 67 (36%), 30 Gy in 10 fractions n = 49 (27%), and 8 Gy in one fraction n = 23 (13%). Group A: n = 33 (18%), median overall survival (OS) 19 days (95% CI 4–33). Group B: n = 84 (46%), median OS 52 days (95% CI 43–60). Group C: n = 67 (36%), median OS 126 days (95% CI 77–174). Median days to in-field progression: Group A 59 days (range 7–109), Group B 96 days (range 19–173), and Group C 97 days (range 13–475). To our knowledge, this is the largest reported retrospective cohort of patients receiving non-ablative palliative RT to treat their primary pancreatic tumors. Most patients had metastatic disease, T4 tumors of the pancreatic head and had not received prior systemic therapy. A significant survival benefit was seen favoring the high dose/longer RT fractionation group, presumably due to appropriate patient selection rather than an RT effect. Despite the relatively short median overall survival, one fifth of the patients were found to experience an in-field progression following RT.