Median EQD2 Research Articles

Radiation Therapy Dose Response in Bulky Relapsed/Refractory Large B-Cell Lymphoma

PurposeTo assess whether a radiotherapy (RT) dose affects response in bulky tumors in relapsed/refractory (r/r) diffuse large B-cell lymphoma (DLBCL). MethodsData from r/r DLBCL patients treated with salvage- or palliative-intent RT (2008-2020) at a single institution were examined. Index lesion size ≥7.5 cm was defined as bulky. Equivalent doses in 2 Gray (Gy) fractions (EQD2) were calculated to compare doses between conventional and hypofractionated (HF, ≥2.5 Gy/fraction) schemes. Objective response rates (ORR) were compared using non-parametric Mann-Whitney U test or Kruskal-Wallis tests with Dunn's multiple comparison corrections. Freedom from local progression (FFLP) was assessed using Kaplan-Meier and Cox proportional hazard regression analyzes. Results183 courses of 151 unique patients were included (salvage: 37%, palliative: 63%). Non-bulky and bulky tumors were irradiated in 109 (60%) and 74 (40%) courses, respectively. Median EQD2 was 33 Gy (IQR=23-39 Gy) with HF in 84 (46%) cases. Of those with post-RT imaging (80%), the ORR was 59% with a trend towards worsened ORR in bulky tumors (50% vs. 65%, p=0.077). For bulky tumors, RT regimens with EQD2s >30 Gy were associated with better ORR (≤30 Gy vs. >30 Gy: 27% vs. 64%, p=0.0073), whereas a lower EQD2 cut-off was sufficient for non-bulky tumors (≤20 Gy vs. >20 Gy: 38% vs. 75%, p=0.0011). On multivariable regression, bulky tumor size was associated with worsened FFLP (HR=2.07, 95% CI=1.16-3.68, p=0.014), while high EQD2s >30 Gy were associated with better FFLP (HR=0.48, 95% CI=0.25-0.93, p=0.031). Bulky tumors treated with EQD2s ≤30 Gy had the lowest median FFLP (4.0 months), while EQD2s >30 Gy had an unreached median FFLP (p=0.0047). ConclusionsBulky r/r DLBCL tumors were associated with less favorable tumor control outcomes in the salvage and palliative settings. RT regimens with higher EQD2s (>30 Gy) should be considered if durable local control of bulky tumors is desired.

High-tailored Anal Canal Radiotherapy (HIT-ART): Outcomes of a 10-Year Single Center Clinical Experience.

The current standard for anal cancer treatment is essentially a 'one size fits all' approach where the dose of radiotherapy is similar whether the tumor is very small or very large. Trials are ongoing to evaluate dose de-escalation or escalation in localized disease depending on tumor size. The aim of the study was to assess results of a personalized approach involving dose stratification by stage and boost dose adjusted according to tumor early response. We retrospectively reviewed squamous cell anal cancer (SCAC) patients treated between 2011 and 2021 by long-course intensity-modulated radiotherapy (IMRT) and concomitant chemotherapy (CT); a sequential boost could be administered by IMRT or interventional radiotherapy (IRT) to obtain a total equivalent dose in 2 Gy (EQD2) of 54-60 Gy. We analyzed 110 patients (61% T3-4 stage, 71% node-positive). A total of 68.2% of patients received a sequential boost, mainly by IRT; median total EQD2 to primary site was 59.3 Gy. Acute ≥G3 toxicity rate was 36.4%. Median follow-up (FUP) was 35.4 months. A total of 83% of patients achieved clinical complete response (cCR); locoregional recurrence (LRR) occurred in 20.9% and distant metastases in 6.4% of cases. A total of 12.7% patients underwent salvage surgery. A total of 25.5% of patients reported ≥G2 and 4.5% ≥G3 late toxicity. The estimated 3-year overall survival, disease-free survival and colostomy-free survival were 92%, 72% and 84% respectively; 3-year-LRR was 22%. Nodal stage was associated with poorer cCR probability and higher LRR (p<0.05). Our results on a large cohort of patients with locally advanced SCAC and long FUP time confirmed the efficacy of IMRT; high local control and manageable toxicity also suggest IRT as a promising method in treatment personalization.

Differential outcomes of re-stratified high-risk prostate cancer patients treated with external beam radiation therapy plus high-dose-rate brachytherapy boost.

We report outcomes of high-risk prostate cancer (PCa) patients, initially classified according to a 3-tier NCCN classification system, treated with external beam radiation therapy (EBRT) and high-dose-rate brachytherapy boost (HDR-BT). Patients were analyzed based on a re-stratification of their risk grouping using CAPRA score and a newer 5-tier NCCN classification. 471 high-risk PCa patients treated with EBRT, HDR-BT, and androgen deprivation therapy (ADT) between 1999 and 2018 were included. Competing risk survival analyses to compare individuals with CAPRA scores < 6 vs. ≥ 6 for biochemical relapse (BCR) and metastasis incidence were conducted. Also, overall survival (OS) for both groups using Kaplan-Meier analysis was assessed. The same analyses were repeated using a 5-tier NCCN stratification comparing those classified as high-risk vs. very high-risk patients. The median age was 71 years, and the median follow-up period was 72 months. The whole cohort received an EQD2 of 74 Gy or greater, with a median EQD2 of 106.89 Gy. Both a CAPRA score ≥ 6 and belonging to the NCCN very high-risk group were associated with BCR, with subdistribution hazard ratios (sHRs) of 3.04 (p = 0.015) and 2.53 (p = 0.013), respectively. For metastasis incidence, both the CAPRA and NCCN groups had similar sHRs of 2.60 (p = 0.094) and 2.71 (p = 0.037), respectively. For 10-year OS, patients with CAPRA score ≥ 6 and belonging to the NCCN very high-risk group presented similar HRs of 2.11 (p = 0.005) and 2.10 (p = 0.002). We showed that high-risk PCa patients classified according to the 3-tier NCCN system benefit from further stratification using the CAPRA score or the 5-tier NCCN stratification method. Patients with a CAPRA score ≥ 6 or classified as very high-risk demonstrate a higher hazard of BCR, metastasis, and death. These patients might benefit from further intensification of their investigations and treatment, based on ongoing research.

Unraveling the safety of adjuvant radiotherapy in prostate cancer: impact of older age and hypofractionated regimens on acute and late toxicity - a multicenter comprehensive analysis.

The objective of this study was to assess the impact of age and other patient and treatment characteristics on toxicity in prostate cancer patients receiving adjuvant radiotherapy (RT). This observational study (ICAROS-1) evaluated both acute (RTOG) and late (RTOG/EORTC) toxicity. Patient- (age; Charlson's comorbidity index) and treatment-related characteristics (nodal irradiation; previous TURP; use, type, and duration of ADT, RT fractionation and technique, image-guidance systems, EQD2 delivered to the prostate bed and pelvic nodes) were recorded and analyzed. A total of 381 patients were enrolled. The median EQD2 to the prostate bed (α/β=1.5) was 71.4 Gy. The majority of patients (75.4%) were treated with intensity-modulated radiation therapy (IMRT) or volumetric-modulated arc therapy (VMAT). Acute G3 gastrointestinal (GI) and genitourinary (GU) toxicity rates were 0.5% and 1.3%, respectively. No patients experienced >G3 acute toxicity. The multivariable analysis of acute toxicity (binomial logistic regression) showed a statistically significant association between older age (> 65) and decreased odds of G≥2 GI acute toxicity (OR: 0.569; 95%CI: 0.329-0.973; p: 0.040) and decreased odds of G≥2 GU acute toxicity (OR: 0.956; 95%CI: 0.918-0.996; p: 0.031). The 5-year late toxicity-free survival rates for G≥3 GI and GU toxicity were 98.1% and 94.5%, respectively. The only significant correlation found (Cox's regression model) was a reduced risk of late GI toxicity in patients undergoing hypofractionation (HR: 0.38; 95% CI: 0.18-0.78; p: 0.008). The unexpected results of this analysis could be explained by a "response shift bias" concerning the protective effect of older age and by treatment in later periods (using IMRT/VMAT) concerning the favorable effect of hypofractionation. However, overall, the study suggests that age should not be a reason to avoid adjuvant RT and that the latter is well-tolerated even with moderately hypofractionated regimens.

Long-Term Toxicity in Patients Receiving Radiotherapy for Ultracentral Stage I Non-Small Cell Lung Cancer – A Secondary Analysis of the LUSTRE Randomized Trial

Hypofractionated and stereotactic body radiotherapy (SBRT) are increasingly used in the treatment of centrally located, early-stage non-small cell lung cancer (NSCLC), though there are concerns of increased morbidity and mortality in patients with ultracentral tumors (UC). We report on the long-term toxicity of patients with UC lung cancer treated on a prospective randomized clinical trial of SBRT versus conventionally hypofractionated radiotherapy (CRT) for stage I NSCLC (NCT01968941). Patients with UC tumors, defined as those where the planning target volume directly overlaps with the proximal bronchial tree (PBT), were identified from the larger cohort of patients treated on the trial. These patients received either SBRT with 60 Gy in 8 fractions or CRT with 60 Gy in 15 fractions. The primary endpoint of this secondary analysis was development of any grade 3 or higher toxicity defined using CTCAE version 3.0. Secondary endpoints included local control, as well as dosimetric analysis of the PBT, using EQD2 with α/β ratio of 3 to assess the relationship between dose to the PBT and toxicity. Twenty-nine patients were identified with UC tumors; 21 received SBRT and 8 received CRT. Median age was 72 years (range 55-88 years) and 59% were female. Median FEV1 was 1.46L (range 0.64-2.37L). Patients had either T1 (59%) or T2 (41%) lesions, with median tumor size 2.5cm (range 1.1-4.9cm). Most patients had histologically confirmed disease (squamous cell, n = 10; adenocarcinoma, n = 8; radiographically suspicious, n = 11). The median follow-up was 2.9 years (range 0.7-5.2 years). The 3-year local control rate of all patients was 88.3% (95% confidence interval: 75.7-100%). There were 3 patients with late (>3 months) grade 3 toxicity (bronchial stricture, chest pain, and atelectasis) and 1 patient with late grade 5 toxicity (bleeding/hemorrhage), all treated in the SBRT arm. Median EQD2 dose to PBT in patients with grade ≥3 late toxicity compared to the rest of the cohort was: Dmax, 132 vs 129 Gy; D0.1cc, 129 vs 119 Gy; D1cc, 124 vs 80 Gy; and D5cc, 83 vs 41 Gy. Median EQD2 volumetric doses in grade ≥3 patients (compared to the rest) to PBT were: V65 Gy, 9.7 vs 2.2cc; V80 Gy, 7.9 vs 1.1cc; V90 Gy, 6.2 vs 0.4cc; and V100 Gy, 4.8 vs 0.3cc. The single patient with grade 5 toxicity had the highest D5cc (116 Gy) and V100 Gy (7cc) among all patients. Stereotactic radiation with 60 Gy in 8 fractions for UC lung cancer provides good local control but carries an approximately 15-20% rate of late grade ≥3 toxicity. There appears to be a dosimetric association between toxicity and dose to the PBT. It may be more important to minimize volumetric PBT dose rather than maximum point dose to reduce risk of severe late toxicity.

Proton Re-Irradiation with Concurrent Hyperthermia in Patients with Recurrent Breast Cancer

The aim of this study is to evaluate the safety and effectiveness of proton re-irradiation with concurrent hyperthermia in the treatment of recurrent breast cancer. We retrospectively identified patients previously treated with photon whole breast or chest wall irradiation for a primary breast cancer at our institution, who subsequently developed a histologically-confirmed locoregional recurrence or new ipsilateral primary breast cancer and underwent proton chest wall re-irradiation with concurrent hyperthermia as part of definitive treatment. Acute toxicity was evaluated once weekly while on-treatment and at 2 weeks and 3 months post-treatment. Toxicities were graded according to CTCAE v4.0. Fifteen patients received proton re-irradiation with concurrent superficial hyperthermia at our institution from August 2018 to December 2022. Median interval between radiation treatment courses was 7.7 years (range 1-30 years). Four patients (26%) had gross, unresected disease at the time of re-treatment. The median initial radiation dose, re-irradiation dose, and cumulative EQD2 was 60.4 Gy (50.6-61.2 Gy), 60 Gy (RBE) (45-66 Gy (RBE)), and 120 Gy (RBE) (103-126 Gy (RBE)), respectively. Patients received a median of 9 (3-14) concurrent hyperthermia treatments delivered twice weekly, and 13 patients (87%) received seven or more hyperthermia treatments. Median toxicity follow-up was 9 months (0-36 months). Acute grade 3 toxicities included two patients (13%) with grade 3 dermatitis, both of which resolved with conservative management within 3 months of treatment completion. Chronic grade 2 or higher toxicities included two grade 2 hyperpigmentation, one grade 3 induration, one grade 2 telangiectasia, and one grade 2 rib fracture. There were no grade 4-5 acute or late toxicities. There was one in-field local recurrence and one regional recurrence outside of the re-irradiation field. Both patients had gross, unresected disease at the time of re-irradiation. Two patients (13%) developed distant disease. Proton re-irradiation with concurrent hyperthermia is feasible and well-tolerated in the re-treatment of breast cancer. Further studies are warranted to determine long-term toxicity and oncologic outcomes.

Prophylactic Para-Aortic Extended Field Irradiation with Concurrent Chemotherapy for FIGO Stage IIIC1 Cervical Cancer Using Intensity Modulated Radiotherapy Technique: Acute Toxicity and Dosimetric Assessment

To evaluate the efficacy of P - PART with concurrent chemotherapy in LACC with the use of intensity modulated radiotherapy technique (IMRT). Our Primary endpoint was to assess acute toxicities and secondary endpoint was to assess loco-regional control (LRC), disease free-survival (DFS), para-aortic recurrence free survival (PA-RFS). A total of 30 patients of squamous cell carcinoma of cervix with stage IIIC1 (FIGO-2018) were recruited in this prospective, single arm interventional phase II study between January 2021 to September 2022. 18FDG-PET CT was performed and those with positive PALN were excluded. IMRT was used to deliver a dose of 50 Gy in 25 fractions to whole pelvis and PALN chain below renal hilum till aortic bifurcation received 45 Gy in 25 fractions. Concurrent cisplatin was administered weekly at 40 mg/m2 during radiation. On completion of external beam radiotherapy, high dose rate intracavitary brachytherapy was given at 7 Gy per fraction in 3 fractions prescribed to HR-CTV. Acute toxicities were assessed using CTCAE version 5.0. Median age was 50 years (37-66 years). All patients had completed treatment as per protocol. All patients had positive pelvic nodes with the maximum nodal short axis dimension of 14 mm (10-18 mm). All patients had positive internal iliac group of LNs, only 2(6.6%) patients had positive common iliac group of Ln. Median number of concurrent cisplatin cycles given were 5 (3-5 cycle). Median overall treatment time was 56 days (52-63 days) and median follow up was 15 months (3-22 month). Median cumulative dose to HR-CTV was 84.3Gy (Range:79.2-86.9Gy). Cumulative median EQD2 to 2cc of bladder and rectum were 69.11Gy (Range:59.17 - 80.07 Gy) and 64.6 Gy (Range: 60.1-66.3Gy) respectively. 7(23.3%) patients having grade 3 diarrhea and 2(6.67%) patients had grade 3 anemia while no significant genitourinary or other toxicities were noted. Patient characteristics, dosimetric data are described in Table-1. All patients underwent clinical and radiological assessment at the time of last follow up with one (3.33%) patient experiencing local failure at 9 months of follow up, hence crude LRC rate is 96.6%, DFS is 13.5 months (5-22 months) and PA-RFS is 16 months (8-23 months) till last date of follow up. Prophylactic EFRT with concurrent chemotherapy using IMRT technique yielded excellent short term clinical outcomes with acceptable toxicity profiles. Longer follow up will elucidate late toxicity and long-term clinical outcomes.

Local Control after Re-Irradiation of Spinal Metastases with Stereotactic Body Radiation Therapy

Determine local control (LC) rate and risk of vertebral compression fractures (VCFs) and radiation myelitis (RM) for patients receiving re-irradiation of spinal metastases (SMs) using stereotactic body radiation therapy (SBRT) from large single-institutional experience with long follow-up. Retrospectively identified patients receiving re-irradiation SBRT (rSBRT, 1, 3, or 5 fractions) to SMs previously treated with radiation therapy (RT) and having follow up imaging to assess local control. 1 fraction patients typically received 20-24 Gy and 16-18 Gy to the high- and low-risk planning target volumes (PTVs), respectively, and 27-39 Gy and 21-24 Gy for the 3 fraction patients, with a single level of 50 Gy for 5 fractions. Patient and treatment characteristics for previous RT (pRT) and rSBRT were collected, including histology and dose-volume histogram statistics (DVH). Kaplan-Meier estimates of overall survival (OS), and cumulative incidence (competing with death) of local failure with death as a competing risk was computed for the whole cohort and stratified by radioresistance of histology, and risk of VCF for RM (for treatments at L1 and above) and 95% confidence intervals. Equivalent dose in 2 Gy fractions (EQD2) for PTV and spinal cord (SC) DVH statistics was computed for each individual course and cumulatively, using a/b = 10 Gy for tumor and 2 Gy for SC. Identified 107 lesions in 91 patients. 48 (45%) had radioresistant histologies. For all patients, at 1 and 2 years, respectively OS was 64% (55-74%) and 43% (34-55%), LC was 88% (81-94%) and 85% (78-91%) with median follow-up of 52 months (Table 1). OS and LC were not significantly different between radiosensitivity groups (p>0.05). Risk of VCF at 1 and 2 years was 7% (3-13%) and 9% (4-16%). RM was identified in 1 patient, who received 30 Gy in 5 fractions to T1, and had 1-fraction rSBRT 21 months later. SC Dmax was 31.5 Gy for pRT and 10.4 Gy, for rSBRT, resulting in total SC EQD2 of 73 Gy. RM was confirmed on MRI 8 months after rSBRT. Cumulative RM risk at 8 months after rSBRT was estimated at 1% (0-4%). Median EQD2 for the minimum dose to the high and low risk PTVs were 17.7 Gy (interquartile range, IQR, 13.0-27.6 Gy) and 13.7 Gy (IQR, 10.8-19.3 Gy) for rSBRT, and maximum EQD to SC for previous RT, rSBRT, and cumulatively was 38 Gy (IQR, 30-41 Gy), 27 Gy (IQR, 22-36 Gy), and 65 Gy (IQR, 54-73 Gy).Re-irradiation of spinal metastasis with SBRT can be delivered safely and provide high rates of local control, including for radioresistant tumors, as demonstrated with the longest reported follow-up in this setting. Re-irradiation of SM with SBRT provides high rates of LC even for radioresistant tumors, and low risk of VCF and RM, based on the longest reported follow-up in this setting.

Clinical and dosimetric outcomes of image-guided, dose-painted radiotherapy in muscle invasive bladder cancer

Purpose/ObjectiveDefinitive radiotherapy (RT) is an alternative to radical cystectomy for select patients with muscle invasive bladder cancer (MIBC); however, there is limited data on dose-painted RT approaches. We report the clinical and dosimetric outcomes of a cohort of MIBC patients treated with dose-painted RT.Material/MethodsThis was a single institution retrospective study of cT2-4N0M0 MIBC patients treated with external beam radiotherapy (EBRT) to the bladder, and sequential or concomitant boost to the tumor bed. The target delineation was guided by either intravesical injection of Lipiodol or through fusion of the pre-treatment imaging. The majority were treated with daily image-guidance. Kaplan-Meier was used to characterize overall survival (OS) and progression-free survival (PFS). Cumulative incidence function (CIF) was used to estimate local (intravesical) recurrence (LR), regional recurrence (RR) and distant metastasis (DM). Univariable and multivariable cause-specific hazard model was used to assess factors associated with LR and OS.Results117 patients were analyzed. The median age was 73 years (range 43, 95). The median EQD2 to the boost volume was 66 Gy (range 52.1, 70). Lipiodol injection was used in 64 patients (55%), all treated with IMRT/VMAT. 95 (81%) received concurrent chemotherapy, of whom, 44 (38%) received neoadjuvant chemotherapy. The median follow-up was 37 months (IQR 16.2, 83.3). At 5-year, OS and PFS were 79% (95% CI 70.5–89.2) and 46% (95% CI 36.5–57.5). Forty-five patients had bladder relapse, of which 30 patients (67%) were at site of the tumor bed. Nine patients underwent salvage-cystectomy. Late high-grade (G3-G4) genitourinary and gastrointestinal toxicity were 3% and 1%.ConclusionPartial boost RT in MIBC is associated with good local disease control and high rates of cystectomy free survival. We observed a pattern of predominantly LR in the tumor bed, supporting the use of a dose-painted approach/de-escalation strategy to the uninvolved bladder. Prospective trials are required to compare oncological and toxicity outcomes between dose-painted and homogeneous bladder RT techniques.

Stereotactic reirradiation with CyberknifeR for locally recurrent prostate cancer, long-term toxicity and clinical outcomes from a monocentric cohort.

Up to 47% of patients with localized prostate cancer (PCa) treated with radiotherapy (EBRT) eventually develop local recurrence. To date, no clear consensus exists on optimal management. A growing body of interest supports the use of stereotaxic re-irradiation (rSBRT), with promising oncological outcomes and low toxicity profile. We collected a single-center case series of locally recurrent PCa who underwent re-irradiation after a previous course of postoperative or definitive radiotherapy. Data from 101 patients treated at our institution for locally recurrent PCa from June 2012 to June 2021 were retrospectively collected. Patients underwent rSBRT with CyberKnife system (Accuray Inc., Sunnyvale, CA, USA), delivered to intraprostatic or macroscopic recurrences within the prostate bed, for a total dose of 30Gy in 5 fractions. All patients received prior EBRT. The median EQD2 total dose was 75.0Gy (range, 60-80Gy). Thirty-two (32%) patients were receiving androgen deprivation therapy (ADT) after prior biochemical recurrence. After a median follow-up of 57.8months, BR occurred in 55 patients (54.5%), with a median BR-free survival (BRFS) of 40.4months (95% C.I. 34.3-58.3). Thirty-two patients (31.7%) developed metastatic disease, with a median metastasis-free survival (MFS) not reached. PSA ≥ 2.5ng/ml and ADT were associated with worst BRFS (26.06 vs. 39.3months, p = 0.03 and 22.7 vs. 27months, p = 0.01, respectively). Castration-resistant status and ADT were found to be predictive of worst MFS (34.1 vs. 50.5months, p = 0.02 and 33.5 vs. 53.1months, p = 0.002, respectively). Concomitant ADT was confirmed as an independent factor for MFS (HR 4.8, 95% CI 1.5-10.6, p = 0.007). No grade > /2 adverse were recorded. After almost 5years of follow-up, with a median BRFS of 40.4months and no grade ≥ 2 AEs, CyberknifeR rSBRT proved effective and safe in a cohort of 101 patients affected by locally recurrent PCa.

&lt;sup&gt;18&lt;/sup&gt;FDG PET-CT significance for post-treatment monitoring in cervical and uterine cancer patients with suspected recurrence in previously irradiated zones

Early detection of cervical (CC) and endometrial (EC) cancer recurrence in previously irradiated areas remains a difficult task for clinicians and radiologists. 18F-FDG PET-CT scope and limits in this matter are not clear yet.Purpose. To determine 18F-FDG PET-CT significance and diagnostic value in differential diagnosis of locoregional recurrence and post-radiation tissue changes in CC and EC patients with suspected relapse in preirradiated zones.Materials and methods. Follow-up data, including multiparametric MRI (T1-WI, T2-WI, DWI, DCE) and 18FFDG PET-CT full descriptions, were studied in 51pts., in 25(49%) CC and 26 (51%) EC Ia–IIIc FIGO, with suspected loco-regional recurrence in pre-irradiated area, 4–96 months after the end of treatment.Adjuvant combined radiotherapy (conformal pelvic EBRT – 3D-CRT, IMRT, VMAT, endovaginal 192Ir HDR brachytherapy) was performed in 33 (64,7%) pts. after radical surgery, adjuvant chemoradiation with Cisplatin 40 mg/m2 or Carboplatin AUC2 weekly – in 8 (24.2%) of them. 18 (35,3%) pts. were treated with definitive chemoradiation, median EQD2 for HR-CTV D90 81.6 ± 4.4 Gy (CI 95% 72.4 Gy – 93.7 Gy) and 54.6 ± 3.3 Gy (CI 95% 48.8–64.2 Gy) for metastatic pelvic and paraaortic lymph nodes.Indications for 18F-FDG PET-CT (Biograph True64, Siemens, 3.8–4.7 MBq/kg, total 169–356 MBq) in all pts. were suspicious clinical, cytological, complex ultrasound, and multiparametric MRI findings in pre-irradiated zones. Any areas of 18F-FDG pathologically increased uptake were considered hypermetabolic lesions, positive for cancer recurrence.Results. No evidence of loco-regional recurrence in pre-irradiated zones was confirmed in 32 (62.7%) pts. Clinical, morphological and radiological signs of progression were obtained in 16 (31.3%) 18F-FDG PET-CTpositive patients, with SUVmax 2.86–8.8 in this subgroup. 18F-FDG PET-CT false-positive results were obtained in 6 (11.8%) patients, false-negative – in 1 (1.9%) heavy pre-treated CC patient. 18F-FDG PET-CT sensitivity was 94.1%, specificity – 84.2%, positive predictive value – 72.7%, negative predictive value – 96.9%.Conclusions. 18F-FDG-PET-CT has a high diagnostic value in the differential diagnosis of loco-regional relapses and post-radiation tissue changes in CC and EC patients with suspected progression in pre-irradiated zones. But 18F-FDG-PET-CT findings evaluation and interpretation requires a multidisciplinary discussion and consensus for this cohort of patients.

Feasibility of vaginal dose points reporting in cancer cervix patients treated by external beam radiotherapy and brachytherapy

Background: Cervical cancer is the second most common malignancy among women in India. The standard of treatment for locally advanced lesions is Concurrent Chemoradiation with External Beam Radiotherapy followed by Intracavitary Brachytherapy (GEC-ESTRO). The dose received by the entire vagina cannot be accurately measured by a vaginal dose point assessment at the level of the ovoids alone. Aims and Objectives: Our study aims to see the feasibility of measuring vaginal dose at various levels and define the dose points that can be practiced in 2D and 3D external radiation and brachytherapy (BT). Materials and Methods: Radiotherapy plans of 29 patients with stages IIA to IVA cancer cervix treated with concurrent chemoradiation from January 2020 to December 2020 were retrospectively reviewed for the feasibility of measuring the vaginal dose points throughout the vagina. Every patient underwent cisplatin-based weekly chemotherapy along with BT and external beam radiotherapy. We have assessed the vaginal dose locations 2 cm above and below the point of the posteroinferior border of the pubic symphysis (PIBS). The superior surface of the ovoid to the PIBS point constitutes the vaginal reference length (VRL). Results: The mean and median doses from external beam radiation therapy (EBRT) were 50Gy and 51 Gy at PIBS, 52 Gy and 53.5 Gy at +2 cm, and 18Gy and 28 Gy at -2 cm, respectively. The combined mean and median EQD2 doses from EBRT and BT at PIBS, PIBS+2, and at PIBS-2 were 56 and 57 Gy, 65 and 66 Gy, and 35 and 31 Gy, respectively. The mean VRL was 5.25 cm before EBRT and 4.75 cm before BT. Conclusion: Our study found that it is feasible to measure the dose received by the vagina using the PIBS system and large dose variations throughout the vagina were observed.

Oncologic outcomes after MRI-assisted image-guided brachytherapy with hybrid interstitial and intra-cavitary applicators under moderate sedation for locally advanced cervix cancer.

To report outcomes of using image-guided hybrid intra-cavitary/interstitial applicators under moderate sedation for locally advanced cervical cancer patients in our institution. A total of 69 fractions of brachytherapy with hybrid applicators were performed in 33 patients from January 2017 to April 2021. All patients underwent MRI pelvis 1 week pre-brachytherapy to determine suitability for interstitial brachytherapy and pre-plan needle placement. All insertion of applicators were performed under moderate sedation with midazolam and/or fentanyl. Fifty-eight (84.1%) fractions were planned with CT alone. Clinical outcomes, dose volume parameters, and toxicities were analyzed. The median follow-up was 28 months. A total of 320 needles (median, 5 needles per fraction) were implanted, with a median insertion depth of 3 cm (range, 1.5-4 cm). The median high-risk clinical target volume (HR-CTV) during initial brachytherapy was 34.5 cc (range, 17.8-74.7 cc). The median total EQD2 D2cc of the rectum, bladder, sigmoid, and small intestine colon was 71.8 Gy, 81.5 Gy, 69 Gy, and 58.3 Gy, respectively. The 2-year local control and overall survival were 80.7% and 77.7%, respectively. Larger volume HR-CTV was significantly associated with worse local control (HR = 1.08, p = 0.005) and overall survival (HR = 1.04, p = 0.015). None of the patients required in-patient admission or blood transfusion post-procedure. Late grade 3 gastrointestinal and genitourinary toxicities were observed in 4 patients (12.2%). Hybrid applicators inserted under moderate sedation are feasible and safe. Image-guided interstitial brachytherapy with CT planning aided by MRI performed 1 week pre-brachytherapy is associated with favorable outcomes and modest toxicities.

Dose-response relationship in patients with newly diagnosed atypical meningioma treated with adjuvant radiotherapy.

This study aimed to identify the radiation dose-response relationship in patients with newly diagnosed atypical meningioma (AM) treated with adjuvant radiotherapy (ART) using conventional fractionation. In total, 158 patients who underwent surgery and ART between 1998 and 2018 were reviewed. Among these patients, 135 with complete information on radiotherapy (RT) dose/fractionation and pathological reports were analyzed. We entered RT dose as a continuous variable into the Cox regression model using penalized spline to allow for a nonlinear relationship between RT dose and events. Local control (LC), progression-free survival (PFS), and overall survival (OS) were evaluated. The corresponding biological equivalent dose in 2Gy fractions (EQD2) was calculated using an α/β ratio of 4Gy. The median follow-up duration was 56.0months. The median ART dose delivered was 61.2Gy in 24-34 daily fractions, corresponding to a median EQD2 of 59.16Gy. In multivariate analysis, larger size and higher mitotic count were associated with significantly reduced LC (P < 0.001 and P = 0.002, respectively), PFS (P < 0.001 and P = 0.006, respectively), and OS (P = 0.006 and P = 0.001, respectively). Meanwhile, a higher RT dose was significantly associated with improved LC, PFS, and OS. Moreover, RT showed a dose-dependent effect on LC, PFS, and OS; local failure, tumor progression, and death were reduced by 12%, 12%, and 16%, respectively, per 1Gy increase in the dose (EQD2). The dose of ART in AM has a dose-response relationship with LC and survival outcomes.

PO30 Presentation Time: 10:30 AM: Intracavitary Brachytherapy Using a Shielded Cylinder, Clinical Use and Patient Toxicity

<h3>Purpose</h3> The utility of shielded cylinder intracavitary brachytherapy applicators in clinical practice has not been reported. We evaluated patients treated using this applicator to report its use in clinical practice and toxicity following treatment. <h3>Materials and Methods</h3> This single institution retrospective study included all patients who received high-dose rate (HDR) intracavitary brachytherapy using a shielded cylinder applicator (#GM11003380, Varian Systems, Palo Alto, CA) as a component of treatment between July 2013-November 2021. Treatment parameters, dosimetry; tumor and treatment characteristics were abstracted from the medical record. Patient toxicities were collected prospectively through an institutional radiation toxicity database. <h3>Results</h3> A total of 48 patients received 188 HDR intracavitary brachytherapy treatments, with 157 using a shielded cylinder. The majority (90%) also received external beam radiation (EBRT) to a median dose of 4500cGy in 25 fractions (interquartile range, IQR, 4500-5625cGy). Common fractionations (fx) for brachytherapy included 2000cGy/4fx with EBRT for patients with recurrent uterine cancer, 2000-2800cGy/4fx with EBRT or 3000cGy/5fx without EBRT for patients with primary vaginal or vulvar cancer, and 500cGy/1fx with EBRT for rectal cancer patients. The median total EBRT + brachytherapy EQD2 was 6930cGy (IQR 6930-7900cGy). In the treatments delivered with a shielded cylinder, shielding was used to reduce dose to rectum (51%), uninvolved vagina (34%), and bladder/urethra (8%). The most common shielding pattern was 180° (78%) and 90° (20%), with a minority of treatments using 270° shielding (2%). In cases where shielding was used to reduce rectal dose, the D2cc[Gy] rectal dose in delivered plans was 1.18Gy (range 0.53 - 3.92Gy). In patients who had both unshielded and shielded treatment plans, the D2cc[Gy] rectal dose was reduced from 4.07Gy to 1.69Gy, respectively. The median total EQD2 rectal dose in patients who received EBRT in 25 fractions in addition to brachytherapy was 38.9Gy (range 14.8 - 47.8Gy). Acute grade 2-3 toxicities included dermatitis (9), cystitis (4), proctitis (3), fatigue (2), nausea (2), pain (2), and anemia (1). In patients who received brachytherapy alone there were no grade 2+ toxicities reported. Late grade 2-3 toxicities reported 6+ months after radiation therapy included vaginal stricture (4), vaginal dryness (1), fatigue (1), lower GI hemorrhage (1), lymphedema (1), urinary frequency (1), and urinary incontinence (1). One patient had a grade 3 vaginal fistula noted at 6-months. There was one grade 2 sacral insufficiency fracture noted at 4-months. There were no acute or late grade 4-5 toxicities. Median follow-up was 35 months (IQR 11-55 months). Fifteen patients died, 6 from cancer progression and 9 from non-cancer causes. Fifteen patients had cancer progression at a median of 28 months from completion of brachytherapy. Five patients had local-only failures, 9 patients had distant-only failures, and 1 patient had pelvic nodal failure. There was no difference in total EQD2 delivered to tumor between those patients who had local failure versus local control, with a median EQD2 of 69.3Gy and 69.5Gy, respectively. The location of local failure was in the unshielded area in three patients and involved the shielded area in two patients. <h3>Conclusions</h3> Shielded cylinder applicators can be utilized successfully in the treatment of well selected patients with primary and recurrent gynecologic cancers and rectal cancers, enabling dose reduction to non-target structures with low treatment-related toxicity.

Dose Response of Bulky Tumors in Relapsed/Refractory Diffuse Large B-Cell Lymphoma

<h3>Purpose/Objective(s)</h3> This study sought to assess whether there is a radiotherapy (RT) dose response for bulky tumors in relapsed/refractory diffuse large B-cell lymphoma (r/r DLBCL). <h3>Materials/Methods</h3> Patients with r/r DLBCL (age ≥18 years) treated with salvage- or palliative-intent RT (2008-2020) at a single institution were included. Course-level data were examined to assess in-field responses of index lesions. Courses used for either post-therapy consolidation, CNS or skin disease, and TBI conditioning were excluded. Index lesion size ≥7.5 cm was considered bulky. EQD2s (α/β = 10) were calculated to accurately compare biologic effective doses between conventional and hypofractionated (≥2.5 Gy/fraction) schemes. Post-treatment responses of index lesions were classified using Lugano Criteria. Objective response rates (ORR), defined as achieving either CR or PR, were compared between non-bulky and bulky tumors using Fisher's exact test. Freedom from local progression (FFLP) and overall survival (OS, patient-level data) from RT start date were recorded. Bulky disease impacts on FFLP and OS were assessed using Kaplan-Meier and multivariable-adjusted Cox proportional hazard regression analyzes. <h3>Results</h3> 151 r/r DLBCL patients underwent 183 RT courses (median follow-up time: 6 months, IQR: 2-17 months). Median age at RT was 67 years (IQR: 56-72 years) with a male/female ratio of 55%/45%. Non-bulky and bulky tumors were treated in 109 (60%) and 74 (40%) cases, respectively. Intent was classified as salvage or palliative in 68 (37%) and 115 (63%) cases, respectively. Median EQD2 was 33 Gy (IQR: 23-39 Gy) with hypofractionation used in 84 (46%) cases. Of those with post-RT imaging (n = 146, 80%), there was a trend towards lower ORR for bulky vs. non-bulky tumors (50% vs. 65%, p = 0.087; CR: 21% vs. 42%, PR: 29% vs. 23%, SD: 28% vs. 14%, PD: 22% vs. 22%). For bulky tumors, RT regimens with EQD2s >30 Gy were associated with better ORR (≤30 Gy vs. >30 Gy: 27% vs. 64%, p = 0.014), whereas a lower EQD2 cut-off was sufficient for non-bulky tumors (<20 Gy vs. ≥20 Gy: 38% vs. 73%, p = 0.0076). In all courses, bulky tumors were significantly associated with shorter FFLP (median: 5.6 months vs. not reached, HR = 2.30, 95% CI: 1.24-4.26, p = 0.0079) and OS (median: 3.7 vs. 10.1 months, HR = 1.66, 95% CI: 1.06-2.58, p = 0.025). Amongst bulky tumors, there was a trend towards improved FFLP with RT regimens with higher EQD2s (20-30 Gy vs. <20 Gy - median: 4.2 vs. 2.3 months, HR = 0.38, 95% CI: 0.09-1.62, p = 0.19; >30 Gy vs. <20 Gy - median: not reached vs. 2.3 months, HR = 0.34, 95% CI: 0.11-1.01, p = 0.053). <h3>Conclusion</h3> In this study, bulky r/r DLBCL tumors were associated with less favorable outcomes in salvage and palliative settings. If durable local control of bulky tumors is needed, RT regimens using higher EQD2s (>30 Gy) should be considered, including cases where shortened, hypofractionated courses are opted for such as during the SARS-CoV-2 pandemic, bridging to CAR-T cell infusion, or prior to allogeneic stem cell transplantation.

Pulsed Reduced Dose Rate (PRDR) Intensity Modulated Radiotherapy for Recurrent Primary Central Nervous System Malignancies: Dosimetric and Clinical Results

<h3>Purpose/Objective(s)</h3> Pulsed reduced dose rate (PRDR) intensity-modulated radiotherapy (IMRT) is a reirradiation approach that may reduce the risk of toxicities in the setting of prior radiotherapy (RT) for recurrent central nervous system (CNS) malignancies. However, toxicities and cumulative doses (in EQD2) to CNS structures are not uniformly reported. We shared our institutional outcomes of PRDR and reported cumulative doses for CNS organs-at-risk (OARs) <h3>Materials/Methods</h3> Consecutive patients diagnosed with recurrent primary CNS tumors treated with PRDR from April 2017 to September 2021 were evaluated. Data collected included number of prior interventions, diagnosis, tumor grade, RT dose and fractionation, cumulative OAR doses, progression-free survival (PFS), overall survival (OS), and adverse events. A systematic review of literature was also performed, and results were compared to this study. <h3>Results</h3> Eighteen patients met inclusion criteria (11 WHO grade 4 glioma, 6 grade 3 glioma, and 1 grade 2 glioma). All patients had at least 1 surgery (range 1-4) and 2 systemic therapy regimens (range 2-6) before PRDR. The median dose for the first course of RT was 59.4 Gy (range: 50-75 Gy) in 33 fractions and the median time from the initial RT to PRDR was 35.6 months (range: 7.0-122.0 months). The median PRDR dose was 45 Gy (range: 36-59.4 Gy) in 25 fractions; the median cumulative EQD2 dose was 107.6 Gy (93.1-132.5 Gy). The median target volume was 134.9 cc (range: 17.9-696.6 cc). The median cumulative EQD2 Dmax values for the brain and brainstem were 111.4 Gy (range: 82.4-175.2 Gy), and 85.4 Gy (range: 14.8-111.6 Gy). At a median follow-up of 6.2 months, grade 2+ treatment-related toxicities were seen in 12 (66.7%) patients. Symptomatic radiation necrosis occurred in 3 (16.7%) patients, the median EQD2 brain Dmax for these patients was 115.9 Gy (110.4-156.7 Gy). In addition, two patients had grade 3 toxicity (fatigue and hearing impairment); no Grade 4+ toxicities were observed. The median PFS and OS after PRDR were 6.3 months (95% Cl: 0.9-11.6 months) and 8.6 months (95% Cl: 4.9-12.3 months), respectively. The systematic review analyzed 5 peer-reviewed studies reporting outcomes for reirradiation with PRDR for 188 patients. The median PRDR dose was 50 Gy (range: 22-60 Gy) in 25 fractions with a median cumulative dose of 110.3 Gy to a median tumor volume of 369.1 cc. At a median follow-up of 8.7 months, the total number of grade 3+ toxicities was 24, but time-dependent analyses were not uniformly reported. <h3>Conclusion</h3> This study supports PRDR reirradiation as a feasible and appropriate strategy for recurrent primary CNS tumors where other options have been exhausted. Despite high cumulative EQD2 to the OARs, the risk of developing high-grade toxicities remains acceptable; the median cumulative brain EQD2 dose for developing necrosis is 115.9 Gy.

Proton Beam Re-Irradiation for In-Field Recurrent Non-Small Cell Lung Cancer after Radiotherapy

<h3>Purpose/Objective(s)</h3> To investigate the safety and effectiveness of re-irradiation with proton beam therapy (PBT) for recurrent non-small cell lung cancer (NSCLC), we retrospectively reviewed clinical outcomes. <h3>Materials/Methods</h3> From April 2009 to July 2021, 26 patients (23 males and 3 females) who were re-irradiated using PBT for recurrence in the irradiation field after radiotherapy for NSCLC, average age 70 years (range 38-88 years), PS 0, 1, 2 = 10, 14, 2 were enrolled in this study. The histology was squamous cell carcinoma in 9 patients, adenocarcinoma in 13, and NSCLC in 4, and all 10 tested for EGFR were negative. The initial treatment was a combination of lung resection and radiation in 4 patients (photon 3, PBT 1), and the remaining were chemoradiotherapy in 6 or radiotherapy alone in 16 (photon 4, PBT 18). The re-irradiation site was peripheral lung field in 22 patients, hilar in 7, and mediastinum in 2. The median tumor diameter was 33.5 mm (12-74 mm), and the clinical re-stage according to the UICC 8th classification was 1, 1, 1, 6, 1, 3, 13, 1 for Stage IA2, IA3, IB, IIA, IIB, IIIA, IIIB, respectively. Beam modulation for PBT was a passive method, with a median re-irradiation dose of 70.4 Gy (RBE) / 32 fr (36-80 Gy (RBE)/10-37 fr). Chemotherapy was used in 7 patients (27%). The overall survival rate (OS), median survival time (MST), local control rate (LC), and recurrence-free survival rate (RFS) were calculated by the Kaplan-Meier method starting from the re-irradiation start date, and the Log-rank test was performed to compare each factor. CTCAE ver5.0 was used to evaluate adverse events. <h3>Results</h3> The median follow-up time was 23.5 months (3-148 months), and the median period from initial to re-irradiation was 16.5 months (5-60 months). Median initial dose was 66 Gy (RBE)/ 27.5 fr (40-85 Gy (RBE)/4-40 fr), median equivalent dose in 2Gy fraction (EQD2) for initial irradiation was 86.4 Gy (RBE) (40-99 Gy (RBE)), and median total EQD2 dose (combined dose of initial and re-irradiation) was 160.4Gy (RBE) (111.6-190.5 Gy (RBE)). Local recurrence was confirmed in 5 patients, regional recurrence in 2, and distant recurrence in 10, and 16 patients died (11 with disease (1 of them was Grade 5), 5 with other diseases). One, 2, 3, 5-year OS; LC; RFS was 84.4%, 61.3%, 47.2%, 27%; 100%, 82.6%, 63.0%, 63.0%; 82.0%, 47.9%, 35.9%, 29.9%, respectively. MST was 18 months. The prognosis for hilar recurrence was statistically significant poor in MST 15 months compared with the mediastinum in 74 months or peripheral lung field in 43 months (p = 0.007). Late adverse events were Grade 2 rib fracture in 1, Grade 2, 3 brachial plexus disorder in 1 each, Grade 2, 3 subcutaneous tissue disorder in 2, 1, Grade 2 pneumonitis in 4, and Grade 5 bronchial fistula in 1 with hilar recurrence. <h3>Conclusion</h3> Proton beam re-irradiation for the NSCLC patients with local recurrence in the previous irradiation field can be a worthwhile salvage treatment. There is a room for further study on re-irradiation for hilar recurrence.

Multi-Institutional Dosimetric Analysis of Toxicity from Definitive SBRT in Cervical Cancer

<h3>Purpose/Objective(s)</h3> Brachytherapy is standard of care in locally advanced cervical cancer. In patients unable to undergo brachytherapy due to complex medical comorbidities, technical reasons, or refusal, treatment with stereotactic body radiotherapy (SBRT) is an option. We report a retrospective analysis of dosimetric parameters and toxicities for definitive cervix patients who received SBRT boost across three institutions. <h3>Materials/Methods</h3> Eligible patients had FIGO IB2-IVB cervical cancer and did not receive brachytherapy. Patient were treated with concurrent chemotherapy and pelvic external beam (EBRT) followed by SBRT with patient immobilization and fiducial image guidance. GTV and HR-CTV were defined according to EMBRACE II guidelines for brachytherapy. Clinicopathological data, dosimetric data, toxicity (CTCAE V 4.0), and outcome data was collected. Spearman correlations completed in R v4.2.1. <h3>Results</h3> 95 patients were included. All patients received EBRT to the pelvis with doses ranging from 45- 51.75Gy in 25-29 fx. SBRT doses to HR-CTV ranged from 16.8-40 Gy given in 4-6 fractions. Median (IQR) HR-CTV volume was 72.6 (58.7). The median total EQD2 were 104.25 (20.3) and SBRT EQD2 60 (20.3). Total EQD2 to 2cc of rectum and bladder were 65.67 (11.9) and 75.8 (21.5). Rates of acute and late grade 1-2 and grade 3 toxicities are reported in Table 1; there were no grade 4+ toxicities. Low grade urinary frequency was the most common reported toxicity and decreased over time. GU stricture (ureteral) was the most common acute grade 3 toxicity and was correlated with EQD2 of EBRT, SBRT, and total dose (P < 0.001), in addition to bladder 2cc SBRT (p = 0.04) and total EQD2 (p=0.02). Fistulas were rare, though some grade 3 fistula occurred. Acute grade 1-2 recto-vaginal fistulas were correlated with EQD2 of EBRT (P < 0.01), SBRT (p= 0.02), and total EQD2 (p=0.02). Late grade 3 fistulas were significantly correlated with HR-CTV volume, EQD2 of EBRT and SBRT (p=0.01) in addition to rectum 2cc SBRT dose (p=0.012), SBRT EQD2 (p=0.01), and total EQD2. <h3>Conclusion</h3> These data suggest that higher bowel/bladder 2cc SBRT and higher total EQD2 is associated with greater rates of acute and late grade 3 bowel and bladder toxicity in a cohort of women receiving SBRT for cervical cancer. Overall rates of ≥ grade 3 toxicities were small and SBRT can be a safe option for patients who cannot receive standard of care brachytherapy, especially when careful attention is given to D2cc volumes.

The Impact of Racial Disparities on Molecular Features, Treatments Rendered and Clinical Outcomes for Patients with Gliomas

<h3>Purpose/Objective(s)</h3> The prognostic role of race on outcomes for patients with gliomas is debated. Historically, trials reporting on race have enrolled low percentages (<3%) of black patients. The primary objective of this study is to characterize racial factors in relation to treatment and clinicopathologic variables for adult glioma patients treated within a multi-center academic network with a large cohort of black patients. We hypothesize that racial factors may impact tumor biology and treatments rendered, and play a prognostic role in patients with gliomas. <h3>Materials/Methods</h3> A retrospective IRB-approved analysis of 241 patients with gliomas treated with curative intent across 4 radiation oncology centers associated with a single academic institution between August 2004 and March 2021 was done. Chi-square tests were done to compare variables stratified by race. Kaplan-Meier (KM) and cox proportional hazard models were used to analyze overall survival (OS), progression free survival (PFS) and freedom from radiation necrosis/treatment effect (RN) for black (B) vs nonblack (NB) patients. Logistic regression was done to analyze association of race with treatment and clinicopathologic variables. <h3>Results</h3> Of the patients included, 140 (58.1%) were male, 101 (41.9%) were female, 33 (13.6%) were black and 208 (86.3%) were nonblack. Black patients were younger (median age 57.5 vs 62.8 yrs; p=0.026) and less likely to receive concurrent temozolomide (TMZ) (71.9% vs 89.9%; p=0.004). Median EQD2 delivered between B vs NB patients was significantly different (50.8 vs 55.4 Gy; p=0.026). There was no significant difference in performance status (p=0.469), MGMT-methylation (p=0.296), IDH-mutation (p=0.447), hypofractionation (p=0.584), adherence to NCCN guidelines (p=0.690), enrollment in clinical trials (p=0.329) or treatment at tertiary sites (p=0.247) for B vs NB patients. On MVA, black race was associated with improved OS (HR 0.555, p=0.027). MGMT methylation was also associated improved OS (HR 0.660, p=0.020). Higher EQD2 was associated with improved OS (HR 0.954, p=0.004) and increased risk of RN (HR1.068, p=0.003). There was no significant difference in median follow up (47.4 vs 36.6 m; p=0.92) or treatment effect (50% survival not reached; p=0.49) between the two groups. Black race improved median PFS (12.7 vs 8.9m, p=0.04) and OS (15.9 vs 10.8m; p=0.063). <h3>Conclusion</h3> In this multi-center analysis examining impact of race in patients with gliomas, black patients were found to have improved OS and PFS, despite being more likely to receive a lower EQD2 dose and less likely to receive concurrent TMZ. Prospective studies to further investigate association of race as a prognostic factor for patients with gliomas are warranted.