Purpose/Objective(s) Patients with brain tumors often experience fatigue after treatment that impacts their quality of life (QOL). Patient-reported outcomes (PROs) including the Brief Fatigue Inventory (BFI) can quantitatively describe the effects of radiotherapy (RT) on patient QOL. Identifying which patient and treatment characteristics predict clinically significant changes in QOL using the minimal clinically important difference (MCID) can help guide treatment decisions and thus improve quality of life. It was previously reported that the MCID of the Brief Fatigue Inventory (BFI) for patients with brain tumors undergoing radiotherapy was 1.33, which was calculated using distribution-based and anchor-based approaches to assess change from baseline to end of treatment (EOT). The purpose of this study was to develop a machine learning variable selection algorithm to determine important patient and treatment predictors of this clinically significant change. Materials/Methods Patients with primary CNS tumors were enrolled on a multi-site prospective registry. Inclusion criteria included curative radiotherapy and completion of the BFI prior to treatment and at EOT. The outcome was a binary variable that measured if a patient experienced an MCID in the negative direction (worse fatigue). The LASSO was used to select important predictors of this outcome. Ten-fold cross-validation was used to increase generalizability of the model. Results Overall, 356 patients had baseline and EOT BFI scores and non-missing values on all predictors included in the LASSO. The median age was 52.2 (range = 18.1-90.9), 55% were males, and 94% were white. Patients received photons (52.8%) or protons (47.2%) with a median dose of 57 Gy (range = 40-76 Gy) over a median of 28 fractions (range = 10-40). The LASSO selected multiple predictors. Reaching the MCID threshold (i.e. clinically worse fatigue after RT) was associated with older age, female, non-white, living in an urban area, less fatigue at baseline, greater dose per fraction, and grade 2+ adverse events (Aes) during treatment. Number of fractions, dose, and modality were not predictive. Conclusion Multiple patient and treatment characteristics were predictive of experiencing an MCID on the BFI. Baseline BFI scores were predictive of the MCID suggesting a ceiling effect such that patients with a high baseline BFI were not likely to get clinically significantly worse. Future research should further explore if other variables, particularly those that can be modified such as dose per fraction, predict clinically significant differences in fatigue and QOL for patients.

OBJECTIVE:The objective of this study was to analyze the hemorrhagic risk of melanoma brain metastases after Gamma Knife radiosurgery (GKRS). METHODS:A prospective institutional database was retrospectively queried to identify patients who underwent GKRS for melanoma brain metastases between 1990 and 2021. Lesional hemorrhage was defined as definite or possible based on radiologists' readings, and severity was graded according to Common Terminology Criteria for Adverse Events. RESULTS:Two hundred ninety-one patients with 1083 lesions treated in 419 sessions were identified. The mean (± SD) patient age was 60 ± 15 years, and 61% were male. The median follow-up period for overall survival (OS) was 11 (range 0-214) months with 581 patient-years. Definite/possible lesional hemorrhages occurred in 13% of lesions, with grade 3 hemorrhages observed in 4% of lesions. Surgical intervention was required in 2% of cases (5% of patients), and all resected lesions were pathologically consistent with melanoma. A decreased risk of definite/possible lesional hemorrhage was associated with a later time period between 2015 and 2021 (OR 0.45, 95% CI 0.266-0.75, p = 0.0021), increased marginal dose (OR 0.91, 95% CI 0.83-0.99, p = 0.037), antiplatelet use post-GKRS (OR 0.195, 95% CI 0.083-0.46, p < 0.001), and whole-brain radiotherapy (WBRT; OR 0.53, 95% CI 0.344-0.82, p = 0.0042). After 2015, more patients received anticoagulation, B-Raf proto-oncogene inhibitors, and immune checkpoint inhibitors, and fewer received bevacizumab (p < 0.001). The cumulative risk of lesional hemorrhage was 17%-20% at 36 months from GKRS, with 95%-96% of cases occurring within 12 months. The median patient OS was 11 (95% CI 9-13) months, and multivariate Cox regression analysis revealed that antiplatelet agents (hazard ratio [HR] 0.66, 95% CI 0.45-0.96, p = 0.031) and immune checkpoint inhibitors (HR 0.35, 95% CI 0.26-0.48, p < 0.001) were associated with longer OS, while WBRT (HR 1.36, 95% CI 1.02-1.81, p = 0.037) and definite/possible hemorrhage (HR 1.39, 95% CI 1.04-1.85, p = 0.024) were associated with shorter OS. CONCLUSIONS:The definite hemorrhage risk of melanoma brain metastases after GKRS was 17% in the first 3 years and 95% of the lesional hemorrhage occurred within the 1st year. Surgical intervention was needed in 5% of patients. Antiplatelet agents and immune checkpoint inhibitors were associated with improved OS, while definite/possible hemorrhage was associated with worse OS.

PURPOSE:When radiation therapy is medically necessary for pregnant patients, photon-based treatments (XRT) have traditionally been used, whereas proton radiation therapy (PRT) is avoided due to concerns about neutron dose. This retrospective study analyzes pregnant patients treated with XRT and models the equivalent dose that would have been delivered to the fetus with proton radiation compared with XRT. The purpose of this work is to provide a comprehensive analysis of pencil beam scanning proton therapy (PBS-PRT) for pregnant patients and to evaluate whether PBS-PRT should be the new standard of practice for treating pregnant patients with brain and head and neck cancers. METHODS AND MATERIALS:PBS-PRT plans were made for seven pregnant patients who received XRT: four treated for brain tumors and three for head and neck tumors. Measurements were performed with the patient plans using an anthropomorphic phantom and Wendi-2 meter placed at the phantom's abdomen. Patient-specific measurements were used to determine the total fetal equivalent dose from PBS-PRT compared with XRT. Imaging dose was also evaluated with a Fluke 451 dose meter. RESULTS:The average measured fetal equivalent dose, accounting for photons and neutrons, for the brain plans was 0.4 mSv for PBS-PRT and 7 mSv for XRT. For the head and neck plans, it was 6 mSv and 90 mSv for PBS-PRT and XRT, respectively. The PBS-PRT plans were preferred by the physicians for both tumor coverage and normal-tissue sparing. Daily imaging added between 0.05 and 1.5 mSv to the total dose. CONCLUSIONS:This retrospective study showed that when treating brain or head and neck cancers in pregnant patients, fetal equivalent dose is reduced by approximately a factor of 10 with PBS-PRT compared with XRT without making any compromises in treatment planning objectives. These results support a change of practice to using PBS-PRT as the new standard for treating pregnant patients with brain or head and neck tumors compared with XRT.

OBJECTIVE:The supplemented Spetzler-Martin (Supp-SM) grading system was developed to improve the predictive accuracy of surgical risk for patients with brain arteriovenous malformations (AVMs). The aim of this study was to apply the Supp-SM grading system to patients having stereotactic radiosurgery (SRS) for Spetzler-Martin (SM) intermediate- (grade III) or high-grade (grade IV-V) AVMs to enable comparison with published microsurgical series.METHODS:In 219 patients who underwent SRS during the period from 1990 to 2016, the Supp-SM grade was calculated for SM grade III (n = 154) or SM grade IV-V (n = 65) AVMs. The Supp-SM grades in these patients were 4 (n = 14, 6%), 5 (n = 36, 16%), 6 (n = 67, 31%), 7 (n = 76, 35%), and 8-9 (n = 26, 12%). Sixty patients (27%) had deep AVMs (basal ganglia, thalamus, or brainstem). Thirty-nine patients (18%) had volume-staged SRS; 41 patients (19%) underwent repeat SRS. The median follow-up period was 69 months for SM grade III AVMs and 113 months for SM grade IV-V AVMs.RESULTS:AVM obliteration was confirmed in 163 patients (74%) at a median of 38 months after initial SRS. The obliteration rates at 4 and 8 years were 59% and 76%, respectively. Thirty-one patients (14%) had post-SRS deficits from hemorrhage (n = 7, 3%) or radiation injury (n = 24, 11%). Six patients (3%) died after SRS (hemorrhage, n = 5; radiation injury, n = 1). The rates of neurological decline or death at 4 and 8 years were 11% and 18%, respectively. Factors predictive of nonobliteration were deep location (HR 0.57, 95% CI 0.39-0.82, p = 0.003) and increasing AVM volume (HR 0.96, 95% CI 0.93-0.99, p = 0.002). Increasing AVM volume was the only factor associated with neurological decline (HR 1.05, 95% CI 1.02-1.08, p = 0.002). The Supp-SM grading score did not correlate with either obliteration (HR 0.94, 95% CI 0.82-1.09, p = 0.43) or neurological decline (HR 1.15, 95% CI 0.84-1.56, p = 0.38).CONCLUSIONS:The Supp-SM grading system was not predictive of outcomes after SRS of intermediate- or high-grade AVM. In a cohort that included a high percentage (47%) of "inoperable" AVMs according to Supp-SM grade (≥ 7), most patients had obliteration after SRS, although there was a high risk of neurological decline.

This retrospective study showed that when treating brain or head and neck tumors in pregnant patients, the equivalent dose a fetus would receive with PRT is approximately a factor of 10 less than XRT without making any compromises in treatment planning. These results support changing the standard of practice to utilizing spot scanning PRT as the preferred method for treating pregnant patients with brain or head and neck tumors when available instead of XRT. We have brought this process to clinic at our center.

INTRODUCTION: The Supplemented Spetzler-Martin (Supp-SM) grading system is predictive of surgical risk for patients with brain arteriovenous malformations (AVM). METHODS: 219 patients had SRS from 1990 to 2016 for SM III (n = 154) or SM IV-V (n = 65) AVM. The Supp-SM grades were 4 (n = 14, 6%), 5 (n = 36, 16%), 6 (n = 67, 31%), 7 (n = 76, 35%), and 8-9 (n = 26, 12%). 60 patients (27%) had deep AVM (basal ganglia, thalamus, or brainstem). 39 patients (18%) had volume-staged SRS; 41 (19%) underwent repeat SRS. The median follow-up was 69 months for grade III AVM and 113 months for grade IV-V AVM. RESULTS: 163 patients (74%) had obliteration at a median of 38 months after initial SRS. The obliteration rates at 4 and 8 years were 59% and 76%, respectively. 31 patients (14%) had post-SRS deficits from hemorrhage (n = 7, 3%) or radiation injury (n = 24, 11%). 6 patients (3%) died after SRS (hemorrhage, n = 5; radiation injury, n = 1). The rates of neurologic decline or death at 4 and 8 years were 11% and 18%, respectively. Factors predictive of non-obliteration were deep location (HR 0.57, 95% CI 0.39-0.82, p = 0.003) and increasing AVM volume (HR 0.96, 95% CI 0.93-0.99, p = 0.002). Increasing AVM volume was the only factor associated with neurologic decline (HR 1.05, 95% CI 1.02-1.08, p = 0.002). The Supp-SM grading system did not correlate with obliteration (HR 0.94, 95% CI 0.82-1.09, p = 0.43) or neurologic decline (HR 1.15, 95% CI 0.84-1.56, p = 0.38). CONCLUSIONS: The Supp-SM grading system was not predictive of outcomes after SRS of intermediate or high-grade AVM. In a cohort which included a high percentage (47%) of “inoperable” AVM (Supp-SM ≥7), most patients had obliteration after SRS, although the chance of neurologic decline was significant.

Purpose Describe a case of intraocular plasmacytoma in a patient with multiple myeloma successfully treated with photon irradiation. Observations A 61-year-old man with a history of relapsing/refractory multiple myeloma and left frontal bone plasmacytoma treated with monthly belantamab mafodotin salvage chemotherapy developed bilateral treatment-related corneal keratopathy. An iris mass was incidentally noted in the right eye during a follow-up examination. The mass was amelanotic with diffuse intrinsic vasculature involving the pupillary margin from 1:30 to 10:30. Fundus examination showed an irregularly shaped amelanotic superotemporal scleral lesion in the right eye and two smaller amelanotic scleral lesions in the left eye. Given known systemic multiple myeloma and history of left frontal bone plasmacytoma, a presumed diagnosis of iris and scleral plasmacytoma was made. Due to rapid progression of the iris plasmacytoma despite systemic chemotherapy, the patient was treated with 20 Gy photon irradiation to the anterior and posterior segments of both eyes. One month after photon irradiation, there was complete regression of the iris plasmacytoma, and the scleral lesions in both eyes also appeared to be regressing despite systemic progression of multiple myeloma. Conclusions and importance Intraocular plasmacytoma is rare and can occur in isolation but typically occurs as a manifestation of systemic multiple myeloma. Intraocular plasmacytoma can be successfully treated with photon irradiation in patients with multiple myeloma who progress on systemic chemotherapy.

Outcomes of patients with stage I-II Hodgkin lymphoma who had uniform

Optic nerve sheath meningiomas (ONSMs) are rare and benign tumors that affect the optic nerve. Although surgical decompression may be used for large tumors that cause mass effect on the surrounding structures, the mainstay of treatment is radiotherapy. We report the case of a 54-year-old female patient who presented with progressive vision loss due to a recurrent right ONSM despite fractionated radiotherapy eight years prior and the subsequent interval regression of the tumor. The optical coherence tomography at the time of recurrence revealed thinning of the right retinal nerve fiber layer. She underwent salvage stereotactic radiosurgery using a marginal dose of 15 Gy. At six months post-radiosurgery, the patient had a dramatic improvement in visual acuity and visual fields despite persistent thinning of the retinal nerve fiber layer. This case illustrates how salvage radiosurgery can be a useful treatment modality in these challenging situations. This tumor’s exophytic growth and the steep dose fall-off of Gamma Knife radiosurgery might favorably affect visual recovery. However, the outcomes of single-session radiosurgery for ONSMs should be further evaluated.

Few studies have explored the impact of rare variants (minor allele frequency, MAF<1%) on highly heritable plasma metabolites identified in metabolomic screens. The Finnish population provides an ideal opportunity for such explorations, given the multiple bottlenecks and expansions that have shaped its history, and the enrichment for many otherwise rare alleles that has resulted. Here, we report genetic associations for 1,391 plasma metabolites in 6,136 men from the late-settlement region of Finland. We identify 303 novel association signals, more than one third at variants rare or enriched in Finns. Many of these signals identify genes not previously implicated in metabolite genome-wide association studies and suggest mechanisms for diseases and disease-related traits.

OBJECTIVE:To determine whether biological effective dose (BED) was predictive of obliteration after stereotactic radiosurgery (SRS) for cerebral arteriovenous malformations (AVMs). PATIENTS AND METHODS:We studied patients undergoing single-session AVM SRS between January 1, 1990, and December 31, 2014, with at least 2 years of imaging follow-up. Excluded were patients with syndromic AVM, previous SRS or embolization, and patients treated with volume-staged SRS. Biological effective dose was calculated using a mono-exponential model described by Jones and Hopewell. The primary outcome was likelihood of total obliteration defined by digital subtraction angiography or magnetic resonance imaging (MRI). Variables were analyzed as continuous and dichotomous variables based on the maximum value of (sensitivity-[1-specificity]). RESULTS:This study included 352 patients (360 AVM, median follow-up, 5.9 years). The median margin dose prescribed was 18.75 Gy (interquartile range [IQR]: 18 to 20 Gy). Two hundred fifty-nine patients (71.9%) had obliteration shown by angiography (n=176) or MRI (n=83) at a median of 36 months after SRS (IQR: 26 to 44 months). Higher BED was associated with increased likelihood of obliteration in univariate Cox regression analyses, when treated as either a dichotomous (≥133 Gy; hazard ratio [HR],1.52; 95% confidence interval [CI], 1.19 to 1.95; P<.001) or continuous variable (HR, 1.00, 95% CI, 1.0002 to 1.005; P=.04). In multivariable analyses including dichotomized BED and location, BED remained associated with obliteration (P=.001). CONCLUSION:Biological effective dose ≥133 Gy was predictive of AVM obliteration after single-session SRS within the prescribed margin dose range 15 to 25 Gy. Further study is warranted to determine whether BED optimization should be considered as well as treatment dose for AVM SRS planning.

PURPOSE:This study compares reduced (<27 Gy) to standard dose (≥30 Gy) radiation therapy (RT) in the treatment of gastric extranodal marginal zone lymphoma of mucosa-associated lymphoid tissue (gMALT lymphoma). METHODS AND MATERIALS:Forty-two patients with stage I or II disease were retrospectively reviewed. Response to RT was assessed with endoscopy after RT. Complete response rate (CR), freedom from treatment failure, and overall survival (OS) were calculated. RESULTS:All patients were stage I (n = 40) or II (n = 2). All patients had residual biopsy proven gMALT lymphoma before RT. Twenty-six patients (61.9%) were treated with standard dose RT, 30 to 36 Gy, and 16 (38.1%) with the reduced dose RT, 23.5 to 27 Gy. The median follow-up was 29.5 months (range, 6-85). Thirty-six patients (86%) achieved complete response (CR), and 6 patients (14%) achieved partial response (PR). The complete response rate (CR) at the first endoscopic assessment, median time of 3 months, was 81% (95% confidence interval, 0.61%-0.93%) for standard RT, and 94% (confidence interval, 0.69%-0.99%) for reduced RT. Among CR patients, one patient had locally relapsed disease at 50 months. The 1-year overall survival (OS) was 100% in both groups. The 1-year freedom from treatment failure (FFTF) was 100% in the reduced RT group and 92% in the standard RT group. The 2-year FFTF and OS of the whole cohort were 92% and 96%, respectively. There was no significant difference in the OS, FFTF, and CR between the 2 treatment groups (P = .38, P = .18, and P = .267, respectively). For toxicity, the mean liver dose and the mean V20 heart dose were significantly lower in the reduced RT group (P <.001 and P = .001, respectively). However, incidence and severity of reported toxicities were similar between the 2 groups. CONCLUSIONS:Reduced dose RT (23.5-27 Gy) achieved excellent complete response rates with minimal toxicity, comparable with standard dose RT (30-36 Gy), for gMALT.

PurposeTo clarify the role of stereotactic radiosurgery (SRS) for atypical meningiomas (AM).MethodsA retrospective analysis of 68 patients with AM having SRS from 1995 until 2019. Nineteen patients (28%) had undergone prior external beam radiation therapy (EBRT) (median dose, 54 Gy). The median follow-up period was 52 months.ResultsEighteen (26%), 17 (25%), and 33 (49%) patients received SRS as an upfront adjuvant (≤ 6 months), early salvage (7-18 months), or late salvage treatment (> 18 months), respectively. The 3-, 5-, and 10-year progression-free survivals (PFSs) were 52%, 35%, and 25%, respectively. The 3-, 5-, and 10-year disease-specific survivals (DSSs) were 85%, 78%, and 61%, respectively. Adverse radiation events (AREs) were observed in 12 patients (18%), with increased or new seizures being the most frequent complication (n=7). Prior EBRT was associated with reduced PFS (HR = 5.92, P <0.01), reduced DSS (HR = 5.84, P <0.01), and an increased risk of ARE (HR = 3.31, P = 0.04). Timing of SRS was correlated with reduced PFS for patients having early salvage treatment compared to upfront adjuvant (HR = 3.17, P = 0.01) or late salvage treatment (HR = 4.39, P <0.01). ConclusionPFS for patients with residual/recurrent AM remains poor despite SRS. Prior EBRT was associated with worse tumor control, higher tumor-related mortality, and an increased risk of ARE. Further study on the timing of SRS is needed to determine if upfront adjunctive SRS improves tumor control compared to salvage SRS.

The aim is to prospectively evaluate the impact of a multidisciplinary lymphoma virtual tumor board. The utility of multi-site interactive lymphoma-specific tumor boards has not been reported. The Mayo Clinic Lymphoma Tumor Board is a component of the International Mayo Clinic Care Network (MCCN). The format includes the clinical case presentation, presentation of radiology and hematopathology findings by the appropriate subspecialist, proposed treatment options, review of the literature pertinent to the case, pharmacy contributions, and discussion followed by recommendations. Three hundred and nine consecutive highly selected real-time cases with a diagnosis of lymphoma were presented at the Mayo Clinic Lymphoma Tumor Board from January 2014 to June 2018 and decisions were prospectively tracked to assess its impact on the treatment decisions. A total of 309 cases were prospectively evaluated. One hundred and forty (45.3%) cases had some changes made or recommended. The total changes suggested were 179, as some cases had more than one recommendation. There were 93 (30%) clinical management recommendations, 45 (14.6%) additional testing recommendations, 29 (9.4%) pathology changes, and 6 (1.9%) radiology changes. In an electronic evaluation process, 93% of the responders reported an improvement in knowledge and competence, and 100% recommended no change in format of the board. A multidisciplinary lymphoma tumor board approach was found to have a meaningful impact on lymphoma patients while enhancing interdisciplinary interactions and education for multiple levels of the clinical care team.

OBJECTIVE:Stereotactic radiosurgery (SRS) is an accepted treatment option for patients with benign parasellar tumors. Here, the authors' objective was to determine the risk of developing new or progressive internal carotid artery (ICA) stenosis or occlusion after single-fraction SRS for cavernous sinus meningioma (CSM) or growth hormone-secreting pituitary adenoma (GHPA). METHODS:The authors queried their prospectively maintained registry for patients treated with single-fraction SRS for CSM or GHPA in the period from 1990 to 2015. Study criteria included no prior irradiation and ≥ 12 months of post-SRS radiological follow-up. Pre-SRS grading of ICA involvement was applied according to the 1993 classification schemes of Hirsch for CSM or Knosp for GHPA. RESULTS:The authors conducted a retrospective review of 283 patients, 155 with CSMs and 128 with GHPAs. Ninety-three (60%) CSMs were Hirsch category 2 and 3 tumors; 97 (76%) GHPAs were Knosp grade 2-4 tumors. Median follow-up after SRS was 6.6 years (IQR 1-24.9 years). No GHPA or category 1 CSM developed ICA stenosis or occlusion. Three (5.2%) patients with category 2 CSMs had asymptomatic ICA stenosis (n = 2) or occlusion (n = 1); 1 (1.1%) category 2 CSM patient had transient ischemic symptoms. Five (14.3%) category 3 CSMs progressed to ICA occlusion (4 asymptomatic, 1 symptomatic). The median time to stenosis/occlusion was 4.8 years (IQR 1.8-7.6). Five- and 10-year risks of ICA stenosis/occlusion in category 2 and 3 CSM patients were 7.5% and 12.4%, respectively. Five- and 10-year risks of ischemic stroke from ICA stenosis/occlusion in category 2 and 3 CSM patients were both 1.2%. Multivariate analysis showed patient age (HR 0.92, 95% CI 0.86-0.98, p = 0.01), meningioma pathology (HR and 95% CI not defined, p = 0.03), and pre-SRS carotid category (HR 4.51, 95% CI 1.77-14.61, p = 0.004) to be associated with ICA stenosis/occlusion. Internal carotid artery stenosis/occlusion was not related to post-SRS tumor growth (HR and 95% CI not defined, p = 0.41). CONCLUSIONS:New or progressive ICA stenosis/occlusion was common after SRS for CSM but was not observed after SRS for GHPA, suggesting a tumor-specific mechanism unrelated to radiation dose. Pre-SRS ICA encasement or constriction increases the risk of ICA stenosis/occlusion; however, the risk of ischemic complications is very low.

BACKGROUND: Surgical resection is typically cited as the optimal treatment of patients with Spetzler-Martin Grade I-II arteriovenous malformation (AVM). OBJECTIVE: To report our experience with single-fraction stereotactic radiosurgery (SRS) for Spetzler-Martin Grade I-II AVM. METHODS: A prospectively maintained registry was reviewed for patients with nonsyndromic Spetzler-Martin Grade I-II AVM having SRS from 1990 to 2011. Patients with <24 mo of follow-up or prior radiotherapy/SRS were excluded, resulting in a study population of 173 patients. Actuarial analysis was performed using the Kaplan-Meier method, and Cox proportional hazards modeling was performed with excellent outcomes (obliteration without new deficits) as the dependent variable. RESULTS: Median post-SRS follow-up was 68 mo (range, 24-275). AVM obliteration was achieved in 132 (76%) after initial SRS. Eleven additional patients achieved obliteration after repeat SRS for an overall obliteration rate of 83%. The rate of obliteration was 60% at 4 yr and 78% at 8 yr. Post-SRS hemorrhage occurred in 7 patients (4%), resulting in 3 minor deficits (2%) and 1 death (<1%). Radiation-induced complications occurred in 5 patients (3%), resulting in minor deficits only. One hundred and thirty-seven patients (79%) had excellent outcomes at last follow-up. CONCLUSION: SRS is a safe and effective treatment for patients with Spetzler-Martin Grade I-II AVM. Selection bias is likely a contributing factor to explain the superior outcomes generally noted in reported series of microsurgery for patients with low grade AVM.

To evaluate our institutional outcomes after treatment of small to medium size choroidal melanoma with low dose COMS brachytherapy. Single center, retrospective review of small to medium size choroidal melanoma < 5 mm in apical height managed from 2005-2019 with 125I brachytherapy at prescribed dose < 80 Gy, using a homogeneous dose calculation methodology. Ocular outcomes included visual acuity, presence of ocular radiation side effects, and local tumor recurrence. The Kaplan-Meier method was used to estimate overall survival, and metastasis rates were reported using cumulative incidence with death as a competing risk. Univariable associations were analyzed using Cox proportional hazards regression. Radiation statistics were calculated using Monte Carlo dosimetry. There were 146 patients included. Patient demographics and presenting tumor features are described in Table 1. Patients were treated with 125I plaque radiotherapy at median dose 65 Gy (IQR: 65-65 Gy) to depth of 5 mm, with additional transpupillary thermotherapy (TTT) at the time of plaque removal in 140 (95.9%) cases. Median follow-up was 6.7 years (IQR: 2.7-9.3 years). At final follow-up, median logMAR visual acuity was 1.1 (IQR: 0.4-2.0) with Snellen acuity 20/15-20/40 (20%), 20/50-20/160 (26%), and 20/200 or worse (54%). Radiation complications were as follows: cystoid macular edema in 54 (38%), radiation maculopathy in 71 (50%), non-proliferative radiation retinopathy in 53 (38%), proliferative radiation retinopathy in 20 (14%), and radiation papillopathy in 53 (38%). There were 11 patients who required subsequent pan-retinal laser photocoagulation (8%). Radiation dose did not appear to impact radiation maculopathy or retinopathy, but radiation papillopathy was significantly associated with point dose, maximum dose, and mean dose to the optic disc (p < 0.05). Local tumor control was achieved in 145 (99.3%) patients with recurrence in 1 (0.7%) patient 6.5 years after plaque. The 5-year cumulative incidence of distant metastasis was 7.2% with 5-year overall survival of 96.2%. Low dose 125I plaque radiotherapy with TTT provided high rates of local tumor control. Radiation maculopathy, retinopathy, and papillopathy were still observed even with reduced radiation apex dose. Future studies are warranted to determine rates of tumor control and ocular toxicity in low dose brachytherapy without TTT.Abstract 3687; TablePatient CharacteristicsMedian age61 years (IQR: 51-68 years)SexFemale 58%ComorbiditiesAtherosclerotic disease 44%Diabetes 18%Hyperlipidemia 45%Hypertension 49%Tumor CharacteristicsMedian logMAR visual acuity0.18 (IQR: 0.0-0.4)Snellen acuity20/15-20/40 68%20/50-20/160 29%20/200 or worse 3%Tumor dimensionsLargest basal diameter (IQR) 8.0 mm (IQR: 6.7-10.0 mm)Thickness (IQR) 2.0 mm (IQR: 2.0-2.0 mm)Secondary retinal detachment18%Subfoveal/subretinal fluid88% Open table in a new tab

Abstract BACKGROUND Treatment of temporal lobe glioma (TLG) frequently includes partial or complete temporal lobectomy (TL) followed by radiotherapy (RT). However, there are two approaches for temporal resection cavity RT, 1) standard target volumes (STV) targeting the entire TL resection cavity, dura, and peri-tumoral brain parenchyma or 2) modified target volumes (MTV) targeting only the adjacent peri-tumoral brain parenchyma. We report patterns of failure and a dosimetric comparison of these approaches. MATERIALS AND METHODS This was a retrospective review of 49 patients with WHO grade II-IV TLG who underwent partial or complete TL and post-operative RT between 1998 and 2018. Progression-free survival (PFS) was estimated using the Kaplan-Meier method. RESULTS The median patient age was 56 years (range,21–76). Patients were diagnosed with glioblastoma (n=32,65%), anaplastic glioma (n=10,20%) and low-grade glioma (n=7,14%). Treatment included partial TL with STV (n=33,67%), partial TL with MTV (n=5,10%), complete TL with STV (n=8,16%) and complete TL with MTV (n=3,6%). Mean RT dose was 60 Gy (range,40–76) in 30 fractions (range,15–39). At median follow-up time of 18 months (range, 3–161), 44 patients (90%) experienced recurrence: 34 (77%) in-field, 5 (11%) out-of-field, and 5 (11%) both in- and out-of-field. Among the 39 in-field failures, the location of recurrence included brain parenchyma (n=38,97%), ventricle (n=6,15%), and dura (n=5,13%). No patient experienced isolated dural recurrence regardless of tumor grade, extent of TL, or radiation volume. Median PFS was 20 months (95% confidence interval [CI]: 15–24). RT volume (STV vs. MTV) was not associated with worsened PFS (hazard ratio: 1.1, 95% CI: 0.5–2.6). MTV was associated with significant reductions in mean or max doses to brain stem, optic chiasm, optic nerves, hippocampus, and pituitary compared to STV. CONCLUSION Omitting RT to the entire TL cavity may reduce dose to multiple normal tissues with no detriments in dural recurrence or PFS.