High Radiation Dose to the Fornix Causes Symptomatic Radiation Necrosis in Patients with Anaplastic Oligodendroglioma.

PURPOSE: Surgery, radiotherapy (RT), and chemotherapy have prolonged the survival of patients with anaplastic oligodendroglioma. However, whether RT induces long-term toxicity remains unknown. We analyzed the relationship between the RT dose to the fornix and symptomatic radiation necrosis (SRN). MATERIALS AND METHODS: A total of 67 patients treated between 2009 and 2019 were analyzed. SRN was defined according to the following three criteria: 1) radiographic findings, 2) symptoms attributable to the lesion, and 3) treatment resulting in symptom improvement. Various contours, including the fornix, were delineated. Univariate and multivariate analyses of the relationship between RT dose and SRN, as well as receiver operating characteristic curve analysis for cut-off values, were performed. RESULTS: The most common location was the frontal lobe (n=40, 60%). Gross total resection was performed in 38 patients (57%), and 42 patients (63%) received procarbazine, lomustine, and vincristine chemotherapy. With a median follow-up of 42 months, the median overall and progression-free survival was 74 months. Sixteen patients (24%) developed SRN. In multivariate analysis, age and maximum dose to the fornix were associated with the development of SRN. The cut-off values for the maximum dose to the fornix and age were 59 Gy (equivalent dose delivered in 2 Gy fractions) and 46 years, respectively. The rate of SRN was higher in patients whose maximum dose to the fornix was >59 Gy (13% vs. 43%, p=0.005). CONCLUSION: The maximum dose to the fornix was a significant factor for SRN development. While fornix sparing may help maintain neurocognitive function, additional studies are needed.

Radiotherapy in adult low-grade glioma: nationwide trends in treatment and outcomes.

BACKGROUND: Management of WHO grade II gliomas (LGG) can include a combination of observation, surgery, radiotherapy (RT), and chemotherapy; however, optimal management remains unclear in regards to RT. OBJECTIVE: The current study seeks to investigate the usage of RT in LGG and its effect on survival outcomes. METHODS: Patients with diagnosis codes specific for LGG were queried from the National Cancer Database (NCDB) during the years 2004-2016. Kaplan-Meier curves with log-rank testing, univariate and multivariate Cox regression analysis, and comparisons of estimated 3- and 7-year survival were performed to investigate the effect of RT on overall survival. RESULTS: 19,382 patients with LGG were identified with histologically confirmed disease. Kaplan-Meier testing demonstrated RT impacted survival in patients undergoing biopsy or no surgery (p < 0.0001), no chemotherapy (p < 0.0001), and in regimens with early RT (p < 0.0001) and high-dose RT (p < 0.0001). Cox multivariate regression demonstrated RT and age less than 40 (HR 0.93, 95% CI 0.89-0.97, p = 0.001), no chemotherapy (HR 0.82, 95% CI 0.77-0.87, p < 0.001), and astrocytoma histology (HR 0.72, 95% CI 0.66-0.79, p < 0.001) were associated with improved survival. 3-year survival of RT versus non-RT groups showed increased survival rates for age less than 40 years (+ 5.7%, p < 0.0001), no surgery or biopsy (+ 8.1%, p < 0.0001), no chemotherapy (+ 10.3%, p < 0.0001), mixed glioma (+ 6.7%, p < 0.0001), astrocytoma (+ 7.1%, p < 0.0001), and in regimens with early RT (+ 7.6%, p < 0.0001) and high-dose RT (+ 4.7%, p < 0.0001). CONCLUSION: This nationwide analysis of LGG patients found that RT was associated with improved survival outcomes in patients less than 40 years of age, with histology subtypes of astrocytoma and mixed glioma, undergoing biopsy or no surgery, and in regimens with early RT and high-dose RT.

Anaplastic Oligodendroglioma - Is Adjuvant Radiotherapy Mandatory following Maximal Surgical Resection?: Grade 3 Oligo Radiotherapy.

BACKGROUND: Current anaplastic oligodendroglioma (AO) management strategies involve surgical resection followed by adjuvant radiotherapy and/or chemotherapy. We investigated a subset of patients at our institution with AO, who, based on their treatment preferences, received surgery without any form of adjuvant therapy. This subset of patients was compared to a cohort with AO who received adjuvant therapy in order to investigate any differences in clinical and survival outcomes. METHODS: A retrospective review of all AO patients treated by the senior author was undertaken between 1994 and 2018. A total of thirty-three cases were identified. Eleven had surgery alone, and twenty-two had surgery with adjuvant therapy. Progression free (PFS) and overall survival (OS) were compared between cohorts and potential confounders were addressed. RESULTS: Gross total resection was achieved in 29 patients, and near total resection in 4 patients. PFS was not statistically different between patients treated with surgery alone versus patients receiving surgery plus adjuvant therapy (surgery alone: 84 ±â€¯16 months; surgery with radiotherapy: 60 ±â€¯9 months; p = 0.08). In addition, OS was also not statistically different between these groups (surgery alone: 215 ±â€¯17 months; surgery with therapy: 241 ±â€¯22 months; p = 0.44). CONCLUSIONS: It is reasonable to consider a "watch and monitor" surveillance strategy in patients who decline adjuvant radiotherapy following surgical resection of their AO. Patients should be made aware that this treatment plan is not standard within current models of care for AO.

Transcription factor networks of oligodendrogliomas treated with adjuvant radiotherapy or observation inform prognosis.

BACKGROUND: Recent international sequencing efforts have allowed for the molecular taxonomy of lower-grade gliomas (LGG). We sought to analyze The Cancer Genome Atlas (TCGA, 2015) gene expression datasets on molecularly defined oligodendrogliomas (IDH-mutated and 1p/19q-codeleted) patients treated with adjuvant radiation or those observed to discover prognostic markers and pathways. METHODS: mRNA expression and clinical information of patients with oligodendroglioma were taken from the TCGA "Brain Lower Grade Glioma" provisional dataset. Transcription factor network reconstruction and analysis were performed using the R packages "RTN" and "RTNsurvival." Elastic net regularization and survival modeling were performed using the "biospear," "plsRCox," "survival" packages. RESULTS: From our cohort of 137 patients, 65 received adjuvant radiation and 72 were observed. In the cohort that received adjuvant radiotherapy, a transcription factor activity signature, that correlated with hypoxia, was associated with shorter disease-free survival (DFS) (median = 45 months vs 108 months, P < .001). This increased risk was not seen in patients who were observed (P = .2). Within the observation cohort, a transcription factor activity signature was generated that was associated with poor DFS (median = 72 months. vs 143 months., P < .01). CONCLUSIONS: We identified a transcription factor activity signature associated with poor prognosis in patients with molecular oligodendroglioma treated with adjuvant radiotherapy. These patients would be potential candidates for treatment intensification. A second signature was generated for patients who were more likely to progress on observation. This potentially identifies a cohort who would benefit from upfront adjuvant radiotherapy.

A Diffuse Leptomeningeal Glioneural Tumor Case Producing Hydrocephalus and Polyradiculopathy

The present report describes the case of a male 17-year-old patient who progressively developed a hydrocephalus and polyradiculopathy due to involvement of central nervous system (CNS) by a diffuse leptomeningeal glioneuronal tumor (DLGNT). The tumor had partial remission in response to the treatment with radiotherapy plus procarbazine, lomustine, and vincristine (PCV) chemotherapy, and the patient had improvement in function and pain levels. The current knowledge about DLGNT, including its clinical manifestations, imaging findings, histological characteristics, and treatment are revised and discussed in the present paper.

[Intracranial Pseudoaneurysm Arising after Radiotherapy for Oligodendroglioma:A Case Report].

Intracranial pseudoaneurysms arising after radiotherapy for brain tumors are a relatively rare occurrence and associated with high-volume radiotherapy such as stereotactic radiosurgery. Herein, the authors report a rare case of intracranial pseudoaneurysm after conventional radiotherapy for oligodendroglioma. Case:A 46-year-old female incidentally presented with an intracranial hemorrhage from a middle temporal artery aneurysm. Four years earlier, she underwent surgical resection and conventional radiation therapy for oligodendroglioma. The aneurysm was successfully treated with middle cerebral artery(MCA)aneurysm trapping, in conjunction with a parietal branch superficial temporal artery-MCA bypass, to prevent re-rupture. Formation of intracranial pseudoaneurysm after conventional radiotherapy is extremely rare. However, the occurrence of cerebral aneurysm(s), as well as vascular stenosis during follow-up for brain tumors treated with radiotherapy, should be considered.

Pattern of failure in anaplastic glioma patients with an IDH1/2 mutation.

PURPOSE: The current study aimed to assess patterns of failure (PoF) in anaplastic glioma (AG) patients managed with intensity-modulated radiation therapy (IMRT) and their relationship to molecular subtype. METHODS: The outcomes of AG patients managed between 2008 and 2014 and entered into a prospective database were assessed, including PoF. AG was initially defined using the WHO 2007 classification, but for analysis, patients were subsequently recategorised based on WHO 2016 as anaplastic oligodendroglioma (AOD), astrocytoma isocitrate dehydrogenase (IDH) mutant (AAmut) or astrocytoma IDH wildtype (AAwt). Management involved IMRT and temozolomide (TMZ), including from 2011 patients with an IDH mutation (IDHmut) planned with 18F-fluoroethyltyrosine (FET) and 18F-fluorodeoxyglucose (FDG) positron-emission tomography (PET). PoF was local, marginal or distant in relation to the IMRT volume. Relapse-free survival (RFS) was calculated from the start of IMRT. RESULTS: A total of 156 patients were assessed, with median follow-up of 5.1 years. Of these patients, 75% were IDHmut, 44% were managed at first or later relapse and 73% received TMZ. Relapse occurred in 68 patients, with 6­year RFS of 75.0, 48.8 and 2.5% for AOD, AAmut and AAwt, respectively (p < 0.001). There was a component of local relapse in 63%, of marginal relapse in 19% and of distant relapse in 37% of relapses. Isolated local, marginal and distant relapse was evident in 51, 9 and 22%, respectively. A distant relapse pattern was more frequent in IDHmut compared to IDHwt patients (26% vs. 45%, p = 0.005), especially within the first 2 years post-IMRT. In multivariate analysis, distant relapse remained associated with AAmut (p < 0.002) and delayed IMRT until the second relapse (p < 0.001). CONCLUSION: Although patients with IDH-mutated AG have improved outcomes, there was a higher proportion of distant relapses occurring during the 2 years after IMRT.

Radiation-Induced Meningiomas: A Series of Four Consecutive Patients and a Review of Literature.

AIM: To assess the clinical outcomes of treatment for radiation-induced meningiomas. MATERIAL AND METHODS: Medical records were retrospectively reviewed for all cranial meningioma cases that were diagnosed and/or underwent surgery at our hospital from 2009 to 2016. All radiation-associated meningioma patients constituted the core sample for this study. RESULTS: This series included one female and three male patients, with a mean age of 47.3 ± 16.3 years. The mean preoperative course was < 3 months. The most common symptom was headache (100%) and three patients had alopecia and thin scalp skin. The mean of the age at which they underwent radiotherapy was 18.5 ± 13.7 years. The mean latency period was 19.2 ± 7.4 years. Initial malignancies included two patients with desmoplastic medulloblastomas (13-year-old female, 65 Gy), (11-year-old male, 54 Gy) and a patient with grade II oligodendroglioma treated with 30 Gy. A male patient received low-dose radiotherapy for chronic otitis at 10 years old. Histopathological examinations revealed the following: 1) fibroblastic-grade I, Ki-67 2%-3%, 25.5 years latency; cerebellopontine angle, 2) atypical meningioma grade II, Ki-67 8%, 21 years, frontal; and 3) transitional grade I, Ki-67 3%-4%, 11 years, frontal. The fourth patient had three radiation-induced meningiomas and 27 radiation-induced cavernomas, and was treated using a gamma knife. The mean follow-up period was 34.8 ± 39.4 months. One patient had rhinorrhea and another experienced a cerebrospinal fluid fistula. Both underwent an additional operation. The former died because of meningitis on postoperative day 31. CONCLUSION: Most radiation-induced meningiomas are low-grade, but they have a high trend of recurrence. Close follow-up and yearly magnetic resonance imaging would minimize the morbidity rate. To reduce fatal complications, surgery should be planned in conjunction with plastic surgeons.

A multi-institutional analysis of clinical outcomes and patterns of care of 1p/19q codeleted oligodendrogliomas treated with adjuvant or salvage radiation therapy.

PURPOSE: Practice patterns vary for adjuvant treatment of 1p/19q-codeleted oligodendroglioma patients. This study evaluates the outcomes of adjuvant (aRT) versus salvage radiation therapy (sRT) in a multi-institutional cohort. METHODS: Oligodendroglioma patients with confirmed 1p/19q codeletion who were treated with RT with or without chemotherapy from 2000 to 2017 at four tertiary centers were retrospectively reviewed. Overall survival (OS), post-RT progression-free survival (PFS), freedom-from-RT (FFRT), and radiation necrosis (RN) rates were determined using Kaplan-Meier analyses. OS1/PFS1 were defined from the initial surgery. OS2/PFS2 were defined from the RT start-date. Multivariable analyses (MVAs) of prognostic factors for OS and PFS were performed with Cox regression. RESULTS: One hundred eighty-six patients were identified: 124(67%) received aRT and 62(33%) received sRT; of sRT patients, 58% were observed after surgery while 42% received chemotherapy without aRT. The median time from initial diagnosis to sRT was 61 months, and 74% had reoperations before sRT. sRT had longer OS1 than aRT (94% vs. 69% at 10 years, p = 0.03) and PFS1 (10-year PFS of 80% vs. 68%, p = 0.03), though sRT was not associated with significantly different OS1/PFS1 on MVAs. Chemotherapy did not delay sRT compared to observation and had worse PFS2 (42% vs. 79% at 5 years, p = 0.08). Higher RT dose was not associated with improved clinical outcomes but was associated with higher symptomatic RN rate (15% vs. 0% at 2 years, p = 0.003). CONCLUSIONS: Delaying RT for selected oligodendroglioma patients appears safe. Adjuvant chemotherapy does not delay sRT longer than observation and may be associated with worse PFS after RT.

Oligodendroglioma confers higher risk of radiation necrosis.

BACKGROUND: Radiation therapy (RT) remains a mainstay for the treatment of lower grade gliomas. Radiation neurotoxicity is a serious complication, carrying high morbidity in the absence of tumor progression. The incidence remains poorly categorized and known risk factors identified are related to the radiation modality. We hypothesized that patients with oligodendroglioma have a higher risk of radiation necrosis (RN) as compared to patients with astrocytoma. METHODS: We conducted a retrospective review of adults with lower grade diffuse gliomas over a 10-year span. The primary outcome was RN, either pathologically confirmed or clinically diagnosed. Cases without pathological confirmation must have been symptomatic, requiring administration of bevacizumab or high-dose steroids. Cox proportional hazard ratios were used for multivariate analyses. RESULTS: In 319 patients, we identified RN in 41 patients (12.9%): 28 patients (21.3%) with oligodendroglioma and 13 (6.9%) with astrocytoma (HR 3.42, p < 0.001). Patients with oligodendroglioma who received > 54 Gy had a higher incidence (31.2%) than those receiving ≤ 54 Gy (14.3%, HR 6.9, p = 0.002). There was no similar correlation among patients with astrocytoma. There was no difference in incidence based on use of concomitant temozolomide. Radiation necrosis appeared within 24 months from radiation in 80.5% of patients. CONCLUSION: Our study suggests that patients with oligodendroglioma are at higher risk of developing RN. The incidence increases with increasing radiation dose in patients with oligodendroglioma but not with astrocytoma. RN usually appears within 24 months from RT. Patients with oligodendroglioma receiving > 54 Gy are at highest risk.

Leksell Radiosurgery for Ependymomas and Oligodendrogliomas.

Stereotactic radiosurgery (SRS) has become a standard management option for less common glial tumors. When imaging defines a recurrent or progressive ependymoma after initial resection in a child who has completed adjuvant fractionated radiation therapy, SRS may be used as a boost or salvage strategy. For patients with oligodendrogliomas diagnosed by biopsy or after cytoreductive surgery, SRS may be used as a primary option in smaller volume tumors, or as an adjuvant option for tumors that have progressed after initial surgery, chemotherapy, or fractionated radiation therapy. Currently the increasing use of molecular markers in both tumors helps to define the prognosis, risk of recurrence, and perhaps response to boost or salvage SRS. This report examines the role of SRS in these less common glial tumors.

Superior Sagittal Sinus Invasion by Malignant Glioma: Case Report and Literature Review

Anaplastic oligodendrogliomas (AOs) correspond to 23% of all oligodendrogliomas. They correspond to a tumor with malignant histological characteristics, focal or diffuse, associated with a worse prognosis. In the present case report, we describe the case of a 30-year-old female submitted to resection of a right parietal lesion whose histology showed to be an AO. She underwent complementary treatment with chemotherapy and radiotherapy according to the Roger Stupp protocol. Four years after the initial diagnosis, there was tumor recurrence within the superior sagittal sinus, with no evidence of recurrence elsewhere. In the literature, we have found no similar published case reinforcing the rarity of this condition.

The effects of tumor size and postoperative radiotherapy for patients with adult low-grade (WHO grade II) infiltrative supratentorial astrocytoma/oligodendroglioma: A population-based and propensity score matched study.

BACKGROUND: The update of 2018 NCCN guidelines (central nervous system cancers) recommended the risk classification of postoperative patients diagnosed as adult low-grade (WHO grade II) infiltrative supratentorial astrocytoma/oligodendroglioma (ALISA/O) should take tumor size into consideration. Moreover, the guidelines removed postoperative radiotherapy (PORT) for low risk patients. Our study aimed to explore the specific tumor size to divide postoperative patients into relatively low- or high risk subgroups and the effect of PORT for ALISA/O patients. METHODS: We conducted a retrospective study choosing 1277 postoperative ALISA/O patients from the Surveillance, Epidemiology, and End Results database. The X-tile analysis provided the optimal cutoff point based on tumor size. The differences between surgery alone and surgery +RT groups were balanced by propensity score-matched analysis. The multivariable analysis and the nomogram evaluated multiple prognostic factors based on cancer-specific survival (CSS) and overall survival (OS). RESULTS: X-tile plots defined 59 mm (P < 0.001) as the optimal cutoff tumor size value in terms of CSS, which was verified in multivariate analysis (P < 0.001). The Kaplan-Meier analysis showed that the surgery alone had higher CSS and OS than surgery +RT, while the low risk group had no statistical significance after propensity score match. Multivariable analysis showed that surgery +RT was independently associated with diminished OS and CSS for high risk group, which had no statistical significance for low-risk group. CONCLUSIONS: Our study suggested that tumor size of 59 mm was an optimal cutoff point to divide postoperative patients into relatively low- or high risk subgroups. PORT may not benefit patients, while the effects of PORT for low risk patients need further research.

Radiotherapy plus temozolomide or PCV in patients with anaplastic oligodendroglioma 1p19q codeleted. / Radioterapia mas temozolomida o PCV en pacientes con oligodendroglioma anaplasico con codelecion 1p19q.

INTRODUCTION: Radiotherapy with procarbazine, lomustine, and vincristine (PCV) improves overall survival in patients with anaplastic oligodendroglioma 1p19q codeleted. PATIENTS AND METHODS: This retrospective analysis investigated outcomes in patients with anaplastic oligodendroglioma 1p19q codeleted compared two different protocols (radiotherapy plus temozolomide or PCV). The primary end points were overall survival and progression-free survival. Secondary endpoint was the radiological response. RESULTS: A total of 48 patients were included. Mean age was 43 years (range: 19-66 years), 26 were male (54.1%). Twenty-one patients received PCV and 27 temozolomide. The baseline characteristics were not difference between the groups. The progression-free survival and overall survival in the PCV group were 7.2 and 10.6 years respectively and temozolomide were 6.1 and 9.2 years, both statistically significant. The radiological response was present in 80.9% in PCV arm and 70.2% in temozolomide arm there was not statistical differences. The multivariate Cox model showed only the significant parameters the use of PCV protocol. The toxicity grade 3 or 4 was present in 42.8% in PCV arm and 11.1% in temozolomide arm. CONCLUSIONS: The most common strategy in the Latin America community is the substitution of the PCV for temozolomide. This retrospective study showed superior efficacy of PCV than temozolomide. The Latin American community effort must be made to be able to have the drugs to available for using as a first line of treatment.

TITLE: Radioterapia mas temozolomida o PCV en pacientes con oligodendroglioma anaplasico con codelecion 1p19q.Introduccion. La radioterapia con procarbacina, lomustina y vincristina (PCV) mejora la supervivencia global en pacientes con oligodendroglioma anaplasico con codelecion 1p19q, pero no esta disponible en America Latina. Pacientes y metodos. Analisis retrospectivo comparando dos protocolos diferentes, radioterapia mas temozolomida o PCV, en pacientes con oligodendroglioma anaplasico con codelecion 1p19q. Los objetivos primarios fueron la supervivencia global y la supervivencia libre de progresion, y el objetivo secundario, la respuesta radiologica. Resultados. Se incluyo a 48 pacientes, 26 de ellos varones (54,1%), con una edad media de 43 años (rango: 19-66 años). Veintiun pacientes recibieron PCV, y 27, temozolomida. Las caracteristicas iniciales no tuvieron diferencias entre los grupos. La supervivencia libre de progresion y la supervivencia global en el grupo con PCV fueron de 7,2 y 10,6 años, y en el grupo de temozolomida, de 6,1 y 9,2 años, respectivamente, unos resultados estadisticamente significativos. Hubo respuesta radiologica en el 80,9% en el brazo de PCV y el 70,2% en el brazo de temozolomida. El analisis multivariado de Cox mostro como unico parametro significativo el uso del protocolo PCV. El grado de toxicidad 3-4 estuvo presente en el 42,8% en el brazo de PCV y en el 11,1% en el brazo de temozolomida. Conclusiones. La estrategia mas comun en America Latina es la sustitucion de PCV por temozolomida. Este estudio retrospectivo mostro una eficacia superior de PCV que de la temozolomida. La diferencia obliga a la comunidad latinoamericana a hacer un esfuerzo colectivo para poder tener acceso a los medicamentos para su uso como primera linea de tratamiento.

[A Rare Case of Radiation-Induced Meningioma that Occurred Only 3 Years and 6 Months after Radiation Therapy for Oligodendroglioma].

We describe an adult case of radiation-induced meningioma(RIM)that was identified within a short interval from the initial treatment for brain tumor. A 45-year-old woman, who had tumor resection followed by radiation therapy for right frontal oligodendroglioma, showed a small enhanced lesion on the right frontal region 3 years and 6 months after the initial radiation therapy. The pathological diagnosis was meningioma(World Health Organization(WHO)grade I)and the Ki-67 labeling index was 3.2%. Most RIMs occur after a long period of time(18.7-24.0 years on average)following radiation therapy. Several studies have suggested that the period before the occurrence of RIM is correlated with both the age of a patient and the radiation dose at the time of radiation therapy. A patient that receives a higher dose of radiation at a younger age has a higher risk of RIM occurrence. In this case, the patient was middle aged;however, she was exposed to a high dose of radiation(54 Gy). High-dose radiation might induce the early onset of RIM. Recently, treatments for glioma have been developed, thus resulting in an increased long-term survival rate among patients. Physicians must pay attention not only to the recurrence of gliomas but also to the occurrence of RIMs.

Association of 1p/19q Codeletion and Radiation Necrosis in Adult Cranial Gliomas After Proton or Photon Therapy.

PURPOSE: To analyze the incidence of and risk factors for clinically significant radiation necrosis (cRN) in adult cranial oligodendrogliomas and astrocytomas treated with proton or photon therapy. METHODS AND MATERIALS: Between 2007 and 2015, 160 patients with grade 2 or 3 oligodendrogliomas (with 1p/19q codeletion, n = 53) or astrocytomas (without 1p/19q codeletion, n = 107) were treated with proton (n = 37) or photon (n = 123) therapy. Clinically significant radiation necrosis (RN) was defined as symptomatic RN or asymptomatic RN that resulted in surgery or bevacizumab administration. The cumulative incidence was calculated using competing risks. Risk factors were identified using Cox proportional hazards. RESULTS: After a median follow-up period of 28.5 months, cRN developed in 18 patients (proton, 6; photon, 12). The 2-year cumulative incidence of cRN for proton and photon therapy was 18.7% (95% confidence interval [CI], 7.5%-33.8%) and 9.7% (95% CI, 5.1%-16%), respectively (P = .16). On multivariate analysis, risk factors for cRN included oligodendroglioma (hazard ratio [HR], 3.57; 95% CI, 1.38-9.25; P = .009) and higher prescription dose (in gray relative biological equivalents [GyRBE]) (HR, 1.30; 95% CI, 1.05-1.61; P = .015). The 2-year cumulative incidence of cRN in oligodendrogliomas and astrocytomas was 24.2% and 6.2%, respectively (P = .01). The relative volume (percentage) of brain receiving 60 GyRBE was a significant dosimetric predictor of cRN in oligodendrogliomas (HR, 1.11; 95% CI, 1.03-1.20; P = .005). CONCLUSIONS: The study showed that 1p/19q codeleted oligodendroglioma was a significant risk factor associated with cRN and the relative volume (percentage) of brain receiving 60 GyRBE was an important dosimetric predictor of cRN for oligodendroglioma patients. There is insufficient evidence at this time to conclude a significant difference in the incidence of cRN between proton and photon therapy.

A case of radiation-induced osteosarcoma of the skull presenting as a cutaneous epidermotropic tumor with a short latent period.

Radiation-induced sarcoma (RIS) is an unusual but well documented tumor. The frequency of RIS of the head and neck region has been reported as 0.143%. In the literature the median interval between irradiation and development of sarcoma is 11 years. Cases of RIS with a short latent period, that is, less than 4 years are rare. We report a case of a 34-year-old female who developed an osteosarcoma of the scalp, over a previous craniotomy scar, 3 years after excision of a frontal anaplastic oligodendroglioma which had been followed by a course of 6 weeks radiotherapy (58 Gy) and 6 cycles of temozolomide. The histological features were those of a high-grade osteosarcoma with epidermotropism of tumor cells. Lymph nodes were partially replaced by high-grade metastatic osteosarcoma, with extra-nodal lymphatic tumor thrombi. To our knowledge the only other case report of post-radiation osteosarcoma with a short latency period was a case of osteosarcoma in the craniofacial bone 3 years after radiotherapy for maxillary squamous cell carcinoma. The histological finding of prominent replacement of the epidermis by osteosarcoma has not been reported before.

Performance of Knowledge-Based Radiation Therapy Planning for the Glioblastoma Disease Site.

PURPOSE: The presence of multiple serial organs at risk (OARs) in close proximity to the tumor makes treatment planning for glioblastoma (GBM) complex and time consuming. The present study aimed to create a knowledge-based (KB) radiation therapy model for GBM patients using RapidPlan. METHODS AND MATERIALS: An initial model was trained using 82 glioblastoma patients treated with 60 Gy in 30 fractions. Plans were created using either volumetric modulated arc therapy (VMAT) or intensity modulated radiation therapy (IMRT). To improve the goodness-of-fit of the model, an intermediate model was generated by using the dose-volume histograms (DVHs) of best spared OARs of the initial model. Using the intermediate model and manual refinement, all 82 cases were replanned, resulting in the final model. The final model was validated on an independent set of 45 patients with GBM, astrocytoma, oligodendroglioma, and meningioma. RESULTS: The plans created by the final model exhibited superior planning target volume (PTV) dose metrics compared with manual clinical plans: ΔD99%=-0.52 ± 0.20 Gy, and ΔD1%=0.80 ± 0.13 Gy (differences are computed as clinical-model). OAR maximum doses were statistically similar, with improved optic apparatus sparing (ΔDmax=2.78 ± 0.82 Gy). Stated improvements correspond to P<.05. The KB planning time is typically 7 minutes for IMRT and 13 minutes for VMAT, compared with a typical 4 hours for manual planning. CONCLUSIONS: The KB approach results in significant improvement in planning efficiency and in superior PTV coverage and better normal tissue sparing irrespective of tumor size and location within the brain.