Abstract
Background
We investigated differences in radiation-induced grade 3+ lymphopenia (G3+L), defined as an absolute lymphocyte count (ALC) nadir of <500 cells/µL, after proton therapy (PT) or ...X-ray (photon) therapy (XRT) for patients with glioblastoma (GBM).
Methods
Patients enrolled in a randomized phase II trial received PT (n = 28) or XRT (n = 56) concomitantly with temozolomide. ALC was measured before, weekly during, and within 1 month after radiotherapy. Whole-brain mean dose (WBMD) and brain dose-volume indices were extracted from planned dose distributions. Univariate and multivariate logistic regression analyses were used to identify independent predictive variables. The resulting model was evaluated using receiver operating characteristic (ROC) curve analysis.
Results
Rates of G3+L were lower in men (7/47 15%) versus women (19/37 51%) (P < 0.001), and for PT (4/28 14%) versus XRT (22/56 39%) (P = 0.024). G3+L was significantly associated with baseline ALC, WBMD, and brain volumes receiving 5‒40 Gy(relative biological effectiveness RBE) or higher (ie, V5 through V40). Stepwise multivariate logistic regression analysis identified being female (odds ratio OR 6.2, 95% confidence interval CI: 1.95‒22.4, P = 0.003), baseline ALC (OR 0.18, 95% CI: 0.05‒0.51, P = 0.003), and whole-brain V20 (OR 1.07, 95% CI: 1.03‒1.13, P = 0.002) as the strongest predictors. ROC analysis yielded an area under the curve of 0.86 (95% CI: 0.79–0.94) for the final G3+L prediction model.
Conclusions
Sex, baseline ALC, and whole-brain V20 were the strongest predictors of G3+L for patients with GBM treated with radiation and temozolomide. PT reduced brain volumes receiving low and intermediate doses and, consequently, reduced G3+L.
Desmoplastic small round cell tumor (DSRCT), which harbors EWSR1-WT1 t(11;22)(p13:q12) chromosomal translocation, is an aggressive malignancy that typically presents as intra-abdominal sarcomatosis ...in young males. Given its rarity, optimal treatment has not been defined.
We conducted a retrospective study of 187 patients with DSRCT treated at MD Anderson Cancer Center over 2 decades. Univariate and multivariate regression analyses were performed. We determined whether chemotherapy, complete cytoreductive surgery (CCS), hyperthermic intraperitoneal cisplatin (HIPEC), and/or whole abdominal radiation (WART) improve overall survival (OS) in patients with DSRCT. Critically, because our institutional practice limits HIPEC and WART to patients with less extensive, potentially resectable disease that had benefited from neoadjuvant chemotherapy, a time-variant analysis was performed to evaluate those adjunct treatment modalities.
The pre-2003 5-year OS rate of 5% has substantially improved to 25% with the advent of newer chemotherapies and better surgical and radiotherapy techniques (HR, 0.47; 95% CI, 0.29-0.75). Chemotherapy response (log rank
= 0.004) and CCS (log rank
< 0.0001) were associated with improved survival. Although WART and HIPEC lacked statistical significance, our study was not powered to detect their potential impact upon OS.
Improved 3- and 5-year OS were observed following multidisciplinary treatment that includes Ewing sarcoma (ES)-based chemotherapy and complete tumor cytoreductive surgery, but few if any patients are cured. Prospective randomized studies will be required to prove whether HIPEC or WART are important. In the meantime, chemotherapy and CCS remain the cornerstone of treatment and provide a solid foundation to evaluate new biologically targeted therapies.
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Efficacy and acute toxicity of proton craniospinal irradiation (p-CSI) were compared with conventional photon CSI (x-CSI) for adults with medulloblastoma.
Forty adult medulloblastoma patients treated ...with x-CSI (n=21) or p-CSI (n=19) at the University of Texas MD Anderson Cancer Center from 2003 to 2011 were retrospectively reviewed. Median CSI and total doses were 30.6 and 54 Gy, respectively. The median follow-up was 57 months (range 4-103) for x-CSI patients and 26 months (range 11-63) for p-CSI.
p-CSI patients lost less weight than x-CSI patients (1.2% vs 5.8%; P=.004), and less p-CSI patients had >5% weight loss compared with x-CSI (16% vs 64%; P=.004). p-CSI patients experienced less grade 2 nausea and vomiting compared with x-CSI (26% vs 71%; P=.004). Patients treated with x-CSI were more likely to have medical management of esophagitis than p-CSI patients (57% vs 5%, P<.001). p-CSI patients had a smaller reduction in peripheral white blood cells, hemoglobin, and platelets compared with x-CSI (white blood cells 46% vs 55%, P=.04; hemoglobin 88% vs 97%, P=.009; platelets 48% vs 65%, P=.05). Mean vertebral doses were significantly associated with reductions in blood counts.
This report is the first analysis of clinical outcomes for adult medulloblastoma patients treated with p-CSI. Patients treated with p-CSI experienced less treatment-related morbidity including fewer acute gastrointestinal and hematologic toxicities.
To report acute toxicities and preliminary outcomes for pediatric patients with ependymomas of the spine treated with proton beam therapy at the MD Anderson Cancer Center.
Eight pediatric patients ...received proton beam irradiation between October 2006 and September 2010 for spinal ependymomas. Toxicity data were collected weekly during radiation therapy and all follow-up visits. Toxicities were graded according to the Common Terminology Criteria for Adverse Events version 3.0.
All patients had surgical resection of the tumor before irradiation (7 subtotal resection and 1 gross total resection). Six patients had World Health Organization Grade I ependymomas, and two had World Health Organization Grade II ependymomas. Patients had up to 3 surgical interventions before radiation therapy (range, 1-3; median, 1). Three patients received proton therapy after recurrence and five as part of their primary management. The entire vertebral body was treated in all but 2 patients. The mean radiation dose was 51.1 cobalt gray equivalents (range, 45 to 54 cobalt gray equivalents). With a mean follow-up of 26 months from the radiation therapy start date (range, 7-51 months), local control, event-free survival, and overall survival rates were all 100%. The most common toxicities during treatment were Grade 1 or 2 erythema (75%) and Grade 1 fatigue (38%). No patients had a Grade 3 or higher adverse event. Proton therapy dramatically reduced dose to all normal tissues anterior to the vertebral bodies in comparison to photon therapy.
Preliminary outcomes show the expected control rates with favorable acute toxicity profiles. Proton beam therapy offers a powerful treatment option in the pediatric population, where adverse events related to radiation exposure are of concern. Extended follow-up will be required to assess for late recurrences and long-term adverse effects.
To describe treatment planning techniques and early clinical outcomes in patients treated with spot scanning proton therapy for chordoma or chondrosarcoma of the skull base.
From June 2010 through ...August 2011, 15 patients were treated with spot scanning proton therapy for chordoma (n=10) or chondrosarcoma (n=5) at a single institution. Toxicity was prospectively evaluated and scored weekly and at all follow-up visits according to Common Terminology Criteria for Adverse Events, version 3.0. Treatment planning techniques and dosimetric data were recorded and compared with those of passive scattering plans created with clinically applicable dose constraints.
Ten patients were treated with single-field-optimized scanning beam plans and 5 with multifield-optimized intensity modulated proton therapy. All but 2 patients received a simultaneous integrated boost as well. The mean prescribed radiation doses were 69.8 Gy (relative biological effectiveness RBE; range, 68-70 Gy RBE) for chordoma and 68.4 Gy (RBE) (range, 66-70) for chondrosarcoma. In comparison with passive scattering plans, spot scanning plans demonstrated improved high-dose conformality and sparing of temporal lobes and brainstem. Clinically, the most common acute toxicities included fatigue (grade 2 for 2 patients, grade 1 for 8 patients) and nausea (grade 2 for 2 patients, grade 1 for 6 patients). No toxicities of grades 3 to 5 were recorded. At a median follow-up time of 27 months (range, 13-42 months), 1 patient had experienced local recurrence and a second developed distant metastatic disease. Two patients had magnetic resonance imaging-documented temporal lobe changes, and a third patient developed facial numbness. No other subacute or late effects were recorded.
In comparison to passive scattering, treatment plans for spot scanning proton therapy displayed improved high-dose conformality. Clinically, the treatment was well tolerated, and with short-term follow-up, disease control rates and toxicity profiles were favorable.
We have previously shown that zebrafish (Danio rerio) embryos can be used as an in vivo model to validate modifiers of the radiation response. Here, we evaluated the radioprotective effect of the ...nanoparticle DF-1, a fullerene with antioxidant properties, in zebrafish embryos.
Zebrafish embryos were exposed to different doses of ionizing radiation ranging from 20 to 80 Gy in the presence and absence of DF-1. Toxicity and radioprotective effects were assessed by monitoring overall survival and morphology as well as organ functions by employing assays to measure kidney excretory function and development of sensory nerve cells (neuromasts). Antioxidant properties of DF-1 were assessed in whole fish.
DF-1 had no apparent adverse effects on normal zebrafish morphology or viability throughout the concentration range tested (1-1,000 micromol/L). Ionizing radiation (10-40 Gy) caused time-dependent and dose-dependent perturbations of normal zebrafish morphology and physiology, notably defective midline development resulting in dorsal curvature of the body axis ("curly-up"), neurotoxicity, impaired excretory function, and decreased survival of the exposed embryos. DF-1 (100 micromol/L) markedly attenuated overall and organ-specific radiation-induced toxicity when given within 3 hours before or up to 15 minutes after radiation exposure. By contrast, DF-1 afforded no protection when given 30 minutes after ionizing radiation. The degree of radioprotection provided by DF-1 was comparable with that provided by the Food and Drug Administration-approved radioprotector amifostine (4 mmol/L). Protection against radiation-associated toxicity using DF-1 in zebrafish embryos was associated with marked reduction of radiation-induced reactive oxygen species.
The fullerene DF-1 protects zebrafish embryos against deleterious effects of ionizing radiation due, in part, to its antioxidant properties.
Abstract
Background
Brainstem toxicity after radiation therapy (RT) is a devastating complication and a particular concern with proton radiation (PBT). We investigated the incidence and clinical ...correlates of brainstem injury in pediatric brain tumors treated with PBT.
Methods
All patients <21 years with brain tumors treated with PBT at our institution from 2007–2019, with a brainstem Dmean >30 Gy and/or Dmax >50.4 Gy were included. Symptomatic brainstem injury (SBI) was defined as any new or progressive cranial neuropathy, ataxia, and/or motor weakness with corresponding radiographic abnormality within brainstem.
Results
A total of 595 patients were reviewed and 468 (medulloblastoma = 200, gliomas = 114, ependymoma = 87, ATRT = 43) met our inclusion criteria. Median age at RT was 6.3 years and median prescribed RT dose was 54Gy RBE. Fifteen patients (3.2%) developed SBI, at a median of 4 months after RT. Grades 2, 3, 4, and 5 brainstem injuries were seen in 7, 5, 1, and 2 patients respectively. Asymptomatic radiographic changes were seen in 51 patients (10.9%). SBI was significantly higher in patients with age ≤3 years, female gender, ATRT histology, patients receiving high-dose chemotherapy with stem cell rescue, and those not receiving craniospinal irradiation. Patients with SBI had a significantly higher V50–52. In 2014, our institution started using strict brainstem dose constraints (Dmax ≤57 Gy, Dmean ≤52.4 Gy, and V54≤10%). There was a trend towards decrease in SBI from 4.4% (2007-2013) to 1.5% (2014–2019) (P = .089) without affecting survival.
Conclusion
Our results suggest a low risk of SBI after PBT for pediatric brain tumors, comparable to photon therapy. A lower risk was seen after adopting strict brainstem dose constraints.
With improvements in survival for patients with metastatic cancer, long-term local control of brain metastases has become an increasingly important clinical priority. While consensus guidelines ...recommend surgery followed by stereotactic radiosurgery (SRS) for lesions >3 cm, smaller lesions (≤3 cm) treated with SRS alone elicit variable responses. To determine factors influencing this variable response to SRS, we analyzed outcomes of brain metastases ≤3 cm diameter in patients with no prior systemic therapy treated with frame-based single-fraction SRS. Following SRS, 259 out of 1733 (15%) treated lesions demonstrated MRI findings concerning for local treatment failure (LTF), of which 202 /1733 (12%) demonstrated LTF and 54/1733 (3%) had an adverse radiation effect. Multivariate analysis demonstrated tumor size (>1.5 cm) and melanoma histology were associated with higher LTF rates. Our results demonstrate that brain metastases ≤3 cm are not uniformly responsive to SRS and suggest that prospective studies to evaluate the effect of SRS alone or in combination with surgery on brain metastases ≤3 cm matched by tumor size and histology are warranted. These studies will help establish multi-disciplinary treatment guidelines that improve local control while minimizing radiation necrosis during treatment of brain metastasis ≤3 cm.
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