Patterns of failure in pediatric medulloblastoma and implications for hippocampal sparing.

BACKGROUND: Hippocampal avoidance (HA) has been shown to preserve cognitive function in adult patients with cancer treated with whole-brain radiation therapy for brain metastases. However, the feasibility of HA in pediatric patients with brain tumors has not been explored because of concerns of increased risk of relapse in the peri-hippocampal region. Our aim was to determine patterns of recurrence and incidence of peri-hippocampal relapse in pediatric patients with medulloblastoma (MB). METHODS AND MATERIALS: We identified pediatric patients with MB treated with protons between 2002 and 2016 and who had recurrent disease. To estimate the risk of peri-hippocampal recurrence, three hippocampal zones (HZs) were delineated corresponding to ≤5 mm (HZ-1), 6 to 10 mm (HZ-2), and >10 mm (HZ-3) distance of the recurrence from the contoured hippocampi. To determine the feasibility of HA, three standard-risk patients with MB were planned using either volumetric-modulated arc therapy (VMAT) or intensity-modulated proton therapy (IMPT) plans. RESULTS: Thirty-eight patients developed a recurrence at a median of 1.6 years. Of the 25 patients who had magnetic resonance imaging of the recurrence, no patients failed within the hippocampus and only two patients failed within HZ-1. The crude incidence of peri-hippocampal failure was 8%. Both HA-VMAT and HA-IMPT plans were associated with significantly reduced mean dose to the hippocampi (p < .05). HA-VMAT and HA-IMPT plans were associated with decreased percentage of the third and lateral ventricles receiving the prescription craniospinal dose of 23.4 Gy. CONCLUSIONS: Peri-hippocampal failures are uncommon in pediatric patients with MB. Hippocampal avoidance should be evaluated in a prospective cohort of pediatric patients with MB. PLAIN LANGUAGE SUMMARY: In this study, the patterns of disease recurrence in patients with a pediatric brain tumor known as medulloblastoma treated with proton radiotherapy were examined. The majority of failures occur outside of an important structure related to memory formation called the hippocampus. Hippocampal sparing radiation plans using proton radiotherapy were generated and showed that dose to the hippocampus was able to be significantly reduced. The study provides the rationale to explore hippocampal sparing in pediatric medulloblastoma in a prospective clinical trial.

Pharmacological Interventions Targeting Pain in Fibrous Dysplasia/McCune-Albright Syndrome.

Fibrous dysplasia (FD) is a rare, non-inherited bone disease occurring following a somatic gain-of-function R201 missense mutation of the guanine-nucleotide binding protein alpha subunit stimulating activity polypeptide 1 (GNAS) gene. The spectrum of the disease ranges from a single FD lesion to a combination with extraskeletal features; an amalgamation with café-au-lait skin hyperpigmentation, precocious puberty, and other endocrinopathies defines McCune-Albright Syndrome (MAS). Pain in FD/MAS represents one of the most prominent aspects of the disease and one of the most challenging to treat-an outcome driven by (i) the heterogeneous nature of FD/MAS, (ii) the variable presentation of pain phenotypes (i.e., craniofacial vs. musculoskeletal pain), (iii) a lack of studies probing pain mechanisms, and (iv) a lack of rigorously validated analgesic strategies in FD/MAS. At present, a range of pharmacotherapies are prescribed to patients with FD/MAS to mitigate skeletal disease activity, as well as pain. We analyze evidence guiding the current use of bisphosphonates, denosumab, and other therapies in FD/MAS, and also discuss the potential underlying pharmacological mechanisms by which pain relief may be achieved. Furthermore, we highlight the range of presentation of pain in individual cases of FD/MAS to further describe the difficulties associated with employing effective pain treatment in FD/MAS. Potential next steps toward identifying and validating effective pain treatments in FD/MAS are discussed, such as employing randomized control trials and probing new pain pathways in this rare bone disease.

Intellectual functioning among case-matched cohorts of children treated with proton or photon radiation for standard-risk medulloblastoma.

BACKGROUND: Proton therapy may reduce cognitive deficits after radiotherapy among brain tumor survivors, although current data are limited to retrospective comparisons between historical cohorts. The authors compared intelligence quotient scores within a case-matched cohort of children with medulloblastoma treated with proton radiation (PRT) or photon radiation (XRT) over the same time period. METHODS: Among 88 consecutive patients with standard-risk medulloblastoma treated with PRT or XRT at 2 institutions from 2000 to 2009, 50 were matched 1:1 (25 with PRT and 25 with XRT) according to age, gender, date of diagnosis, histology, radiation boost, and craniospinal irradiation dose. One-way analyses of variance were performed to compare the Full-Scale Intelligence Quotient (FSIQ) and associated index scores between the 2 cohorts. RESULTS: Neurocognitive data were available for 37 survivors (17 with PRT and 20 with XRT) from the matched cohort. The mean age was 8.5 years (SD, 4.14 years). The median follow-up was 5.3 years (range, 1.0-11.4 years) and 4.6 years (range, 1.1-11.2 years) for the PRT and XRT cohorts, respectively (P = .193). Patients treated with PRT had significantly higher mean FSIQ (99.6 vs 86.2; P = .021), verbal (105.2 vs 88.6; P = .010), and nonverbal scores (103.1 vs 88.9; P = .011) than the XRT-treated cohort. Differences in processing speed (82.9 vs 77.2; P = .331) and working memory (97.0 vs 92.7; P = .388) were not statistically significant. CONCLUSIONS: Radiotherapy-associated cognitive effects appear to be more attenuated after proton therapy. Comprehensive prospective studies are needed to appropriately evaluate the neurocognitive advantages of proton therapy.

Clinical outcomes of pediatric patients with autism spectrum disorder and other neurodevelopmental disorders and intracranial germ cell tumors.

INTRODUCTION: Intracranial germ cell tumors (IGCTs) are rare tumors of the central nervous system with peak incidence around puberty. Given the developmental origins of IGCTs, we investigated the prevalence of neurodevelopmental disorders (NDDs) in patients with IGCTs and characterized outcomes for patients with NDD and IGCTs. METHODS: A retrospective review of medical records was conducted for 111 patients diagnosed with IGCTs between 1998 and 2018 and evaluated at the Massachusetts General Hospital. Kaplan-Meier method and log-rank test was used for survival analyses. Cox regression analyses were performed for parameters associated with progression-free survival (PFS). RESULTS: Median age at IGCT diagnosis was 12.8 years (range: 4.3-21.7) and median follow-up was 6.5 years (range: 0.2-20.5). Eighteen patients were diagnosed with NDDs prior to IGCT diagnosis, including five patients with autism spectrum disorder (ASD). Of the 67 patients with pure germinomas, four (6.0 %) had prior ASD diagnoses. Patients with NDD had significantly inferior PFS in the nongerminomatous germ cell tumor (NGGCT) cohort. On univariate and multivariable analyses, craniospinal irradiation (CSI) was significantly associated with improved PFS in the NGGCT cohort. CONCLUSIONS: Our study found an ASD prevalence in the pure germinoma cohort more than threefold greater than the national prevalence, suggesting an association between ASD and pure germinomas. Furthermore, patients with NDD and NGGCT had worse PFS, possibly due to fewer patients with NDD receiving CSI. Future prospective studies with larger cohorts are needed to examine associations between NDDs and IGCTs, and further characterize outcomes for patients with NDDs and IGCTs.

Quality of life in patients with proton-treated pediatric medulloblastoma: Results of a prospective assessment with 5-year follow-up.

BACKGROUND: To the authors' knowledge, health-related quality of life (HRQOL) outcomes are not well described in patients with medulloblastoma. The use of proton radiotherapy (RT) may translate into an improved HRQOL. In the current study, the authors report long-term HRQOL in patients with proton-treated pediatric medulloblastoma. METHODS: The current study was a prospective cohort HRQOL study of patients with medulloblastoma who were treated with proton RT and enrolled between August 5, 2002, and October 8, 2015. Both child report and parent-proxy report Pediatric Quality of Life Inventory (PedsQL) surveys were collected at baseline during RT and annually thereafter (score range on surveys of 0-100, with higher scores indicating better HRQOL). Patients were dichotomized by clinical/treatment variables and subgroups were compared. Mixed-model analysis was performed to determine the longitudinal trajectory of PedsQL scores. The Student t test was used to compare long-term HRQOL measures with published means from a healthy child population. RESULTS: Survey data were evaluable for 116 patients with a median follow-up of 5 years (range, 1-10.6 years); the median age at the time of diagnosis was 7.6 years (range, 2.1-18.1 years). At baseline, children reported a total core score (TCS) of 65.9, which increased by 1.8 points annually (P<.001); parents reported a TCS of 59.1, which increased by 2.0 points annually. Posterior fossa syndrome adversely affected baseline scores, but these scores significantly improved with time. At the time of last follow-up, children reported a TCS of 76.3, which was 3.3 points lower than that of healthy children (P = .09); parents reported a TCS of 69, which was 11.9 points lower than that of parents of healthy children (P<.001). Increased follow-up time from diagnosis correlated with improved HRQOL scores. CONCLUSIONS: HRQOL scores appear to increase over time after treatment in children treated with proton RT for medulloblastoma but remain lower compared with those of parent-proxy reports as well as published means from a healthy normative sample of children. Additional follow-up may translate into continued improvements in HRQOL. Cancer 2018. © 2018 American Cancer Society.

Left hippocampal dosimetry correlates with visual and verbal memory outcomes in survivors of pediatric brain tumors.

BACKGROUND: Radiotherapy (RT) in the pediatric brain tumor population causes late neurocognitive effects. In the current study, the authors investigated associations between clinical and dosimetric risk factors and memory outcomes in a cohort of patients treated with proton radiotherapy (PRT). METHODS: A total of 70 patients (median age at PRT, 12.1 years [range, 5.0-22.5 years]) who were treated with PRT were identified with baseline and follow-up evaluations of visual and verbal memory (Children's Memory Scale and the third edition of the Wechsler Memory Scale). Whole-brain as well as bilateral hippocampal and temporal lobe contours were delineated for the calculation of dosimetric indices. Multivariate analyses were performed to assess associations of score changes over time with clinical factors and dosimetric indices. RESULTS: The median neurocognitive follow-up was 3.0 years (range, 1.1-11.4 years). For the entire cohort, delayed and immediate verbal memory scaled scores demonstrated small declines. The mean decline for delayed verbal memory scores was 0.6 (P = .01), and that for immediate verbal memory scores was 0.5 (P = .06). Immediate and delayed visual memory scores were not found to change significantly (+0.1 and -0.3, respectively; P>.30). A higher left hippocampal V20GyE (percentage of the volume of a particular anatomical region receiving at least a 20 gray equivalent) was correlated with a score decline in all 4 measures. Female sex was found to be predictive of lower delayed verbal memory follow-up scores (P = .035). CONCLUSIONS: Only delayed verbal memory scores were found to have declined statistically significantly at follow-up after PRT, reflecting some weakness in verbal memory retrieval. Given a correlation of left hippocampal dosimetry and memory outcomes after PRT, left hippocampal-sparing PRT plans may assist patients with pediatric brain tumors in preserving memory-retrieval abilities. Cancer 2018;124:2238-45. © 2018 American Cancer Society.

Adjuvant Antiangiogenic Treatment for Aggressive Giant Cell Lesions of the Jaw: A 20-Year Experience at Massachusetts General Hospital.

PURPOSE: To document long-term outcomes using a standardized treatment protocol of enucleation with preservation of vital structures and adjuvant subcutaneous interferon for aggressive giant cell lesions (GCLs) of the jaws. MATERIALS AND METHODS: A retrospective cohort study was designed. We evaluated all patients treated at Massachusetts General Hospital from April 1995 through September 2015 by enucleation with preservation of vital structures and adjuvant daily subcutaneous interferon for aggressive GCLs. The sample included patients with complete medical records consisting of clinical, radiographic, histopathologic, and follow-up data. The exclusion criteria included patients with incomplete records, contraindications to interferon therapy, non-aggressive GCLs, and GCLs associated with syndromes or with hyperparathyroidism. The primary outcome variable was long-term progression-free survival (PFS). The secondary outcome variables were adverse effects and laboratory abnormalities classified by type, frequency, and severity. Predictor variables for recurrence or failure included age, gender, location and features of lesion, type of procedure, duration of interferon treatment, amount of bone fill at end of treatment, and adverse effects. Descriptive statistics, Kaplan-Meier survival analysis, and Cox proportional hazards regression analysis were computed. RESULTS: Of a total of 77 patients, 45 (mean age, 18.8 ± 12.5 years; 29 female patients; 36 in whom the mandible was affected) met the inclusion criteria. The mean duration of interferon therapy was 7.9 ± 2.3 months. After follow-up of 4.8 ± 3.9 years, 6 patients showed progression of the lesion, considered recurrence (13.3% failure rate, 82.6% PFS rate). Most patients had mild (n = 42; 93.3%) and/or moderate (n = 31; 68.8%) side effects, which were readily managed. Adverse effects required stoppage of interferon in 7 patients, whereas no patients had long-term toxicity. No variable was significantly associated with PFS. CONCLUSIONS: The results of this study indicate that enucleation with preservation of vital structures in combination with adjuvant interferon alfa is a reliable treatment for aggressive GCLs of the jaws associated with a low recurrence rate.

Genetic Analysis of Giant Cell Lesions of the Maxillofacial and Axial/Appendicular Skeletons.

PURPOSE: To compare the genetic and protein expression of giant cell lesions (GCLs) of the maxillofacial (MF) and axial/appendicular (AA) skeletons. We hypothesized that when grouped according to biologic behavior and not simply by location, MF and AA GCLs would exhibit common genetic characteristics. MATERIALS AND METHODS: This was a prospective and retrospective study of patients with GCLs treated at Massachusetts General Hospital from 1993 to 2008. In a preliminary prospective study, fresh tissue from 6 aggressive tumors each from the MF and AA skeletons (n = 12 tumors) was obtained. RNA was extracted and amplified from giant cells (GCs) and stromal cells first separated by laser capture microdissection. Genes highly expressed by GCs and stroma at both locations were determined using an Affymetrix GeneChip analysis. As confirmation, a tissue microarray (TMA) was created retrospectively from representative tissue of preserved pathologic specimens to assess the protein expression of the commonly expressed genes found in the prospective study. Quantification of immunohistochemical staining of MF and AA lesions was performed using Aperio image analysis to determine whether immunoreactivity was predictive of aggressive or nonaggressive behavior. RESULTS: Five highly ranked genes were found commonly in GCs and stroma at each location: matrix metalloproteinase-9 (MMP-9), cathepsin K (CTSK), T-cell immune regulator-1 (TCIRG1), C-type lectin domain family-11, and zinc finger protein-836. MF (n = 40; 32 aggressive) and AA (n = 48; 28 aggressive) paraffin-embedded tumors were included in the TMA. The proteins CTSK, MMP-9, and TCIRG1 were confirmed to have abundant expression within both MF and AA lesions. Only the staining levels for TCIRG1 within the GCs predicted the clinical behavior of the MF lesions. CONCLUSIONS: MMP-9, CTSK, and TCIRG1 are commonly expressed by GCLs of the MF and AA skeletons. This supports the hypothesis that these lesions are similar but at different locations. TCIRG1 has not been previously associated with GCLs and could be a potential target for molecular diagnosis and/or therapy.

Long-term toxic effects of proton radiotherapy for paediatric medulloblastoma: a phase 2 single-arm study.

BACKGROUND: Compared with traditional photon radiotherapy, proton radiotherapy irradiates less normal tissue and might improve health outcomes associated with photon radiotherapy by reducing toxic effects to normal tissue. We did a trial to assess late complications, acute side-effects, and survival associated with proton radiotherapy in children with medulloblastoma. METHODS: In this non-randomised, open-label, single-centre, phase 2 trial, we enrolled patients aged 3-21 years who had medulloblastoma. Patients had craniospinal irradiation of 18-36 Gy radiobiological equivalents (GyRBE) delivered at 1·8 GyRBE per fraction followed by a boost dose. The primary outcome was cumulative incidence of ototoxicity at 3 years, graded with the Pediatric Oncology Group ototoxicity scale (0-4), in the intention-to-treat population. Secondary outcomes were neuroendocrine toxic effects and neurocognitive toxic effects, assessed by intention-to-treat. This study is registered at ClinicalTrials.gov, number NCT00105560. FINDINGS: We enrolled 59 patients from May 20, 2003, to Dec 10, 2009: 39 with standard-risk disease, six with intermediate-risk disease, and 14 with high-risk disease. 59 patients received chemotherapy. Median follow-up of survivors was 7·0 years (IQR 5·2-8·6). All patients received the intended doses of proton radiotherapy. The median craniospinal irradiation dose was 23·4 GyRBE (IQR 23·4-27·0) and median boost dose was 54·0 GyRBE (IQR 54·0-54·0). Four (9%) of 45 evaluable patients had grade 3-4 ototoxicity according to Pediatric Oncology Group ototoxicity scale in both ears at follow-up, and three (7%) of 45 patients developed grade 3-4 ototoxicity in one ear, although one later reverted to grade 2. The cumulative incidence of grade 3-4 hearing loss at 3 years was 12% (95% CI 4-25). At 5 years, it was 16% (95% CI 6-29). Pediatric Oncology Group hearing ototoxicity score at a follow-up of 5·0 years (IQR 2·9-6·4) was the same as at baseline or improved by 1 point in 34 (35%) of 98 ears, worsened by 1 point in 21 (21%), worsened by 2 points in 35 (36%), worsened by 3 points in six (6%), and worsened by 4 points in two (2%). Full Scale Intelligence Quotient decreased by 1·5 points (95% CI 0·9-2·1) per year after median follow-up up of 5·2 years (IQR 2·6-6·4), driven by decrements in processing speed and verbal comprehension index. Perceptual reasoning index and working memory did not change significantly. Cumulative incidence of any neuroendocrine deficit at 5 years was 55% (95% CI 41-67), with growth hormone deficit being most common. We recorded no cardiac, pulmonary, or gastrointestinal late toxic effects. 3-year progression-free survival was 83% (95% CI 71-90) for all patients. In post-hoc analyses, 5-year progression-free survival was 80% (95% CI 67-88) and 5-year overall survival was 83% (95% CI 70-90). INTERPRETATION: Proton radiotherapy resulted in acceptable toxicity and had similar survival outcomes to those noted with conventional radiotherapy, suggesting that the use of the treatment may be an alternative to photon-based treatments. FUNDING: US National Cancer Institute and Massachusetts General Hospital.

Rapid Neurological Recovery Following Partial Surgical Resection of Spinal Glioblastoma Multiforme in a Pediatric Patient Presenting With Complete Paraplegia.

Pediatric spinal cord glioblastoma multiforme is a rare entity with a poor prognosis often presenting with lower extremity weakness or paralysis. Previous literature suggests that aggressive surgical resection may provide overall survival benefit; however, there is limited concurrent analysis demonstrating neurological recovery following surgical resection. We report the case of a 9-year-old boy who presented with complete paraplegia and regained the ability to ambulate independently following subtotal surgical resection, radiation, and chemotherapy. The case demonstrates the balance between meaningful neurological recovery and overall survival when deciding on the extent of resection in cases of pediatric spinal glioblastoma multiforme.

Proton therapy for pediatric and adolescent esthesioneuroblastoma.

BACKGROUND: Esthesioneuroblastoma (EN) of the paranasal sinus comprises less than 3% of tumors of in pediatric and adolescent patients [1]. The collective adult literature indicates a critical role for radiotherapy in attaining cure [2], yet pediatric outcome data is limited. Radiation in pediatric patients with EN can cause significant morbidity due to the proximity of critical structures. Proton radiotherapy offers a potential dosimetric benefit that may improve long-term survival and toxicity outcomes in the pediatric population [3]. METHODS: We retrospectively identified eight patients treated for EN with proton radiotherapy from 2000-2013. Times to event clinical endpoints are summarized using the Kaplan-Meier methods and are from the date of radiotherapy completion. Toxicities are reviewed and graded according to CTCAE v. 4.0. RESULTS: Median follow up was 4.6 years for survivors (range 0.8-9.4 years). The 4 year overall survival was 87.5%. Four of eight patients (one elective) had comprehensive neck radiotherapy. No local or regional failures were observed. Two patients failed distantly with diffuse leptomeningeal disease and intraparenchymal brain metastases, at 0.6 and 1.3 months respectively. Four patients developed radiation related late toxicities including endocrine dysfunction, two cases of grade 2 retinopathy and one case of grade 3 optic neuropathy. CONCLUSIONS: In a limited cohort, proton radiotherapy appears to provide excellent locoregional disease control even in those patients with locally advanced disease and intracranial extension. Distant failure determined overall survival in our cohort. Toxicities were acceptable given disease location and extent.

Novel molecular pathways in Gorham disease: implications for treatment.

Rapid advances in evidence-based treatment schedules are a hallmark of modern oncology. In rare neoplastic diseases, however, clinical expertise is hard to build and evidence based on randomized trials almost impossible to collect. Gorham disease is a rare form of lymphatic proliferation accompanied by osteolysis, which usually occurs in young adults. Despite the fact that the clinical course of Gorham disease is often devastating and occasionally fatal, insights into its biological background are sparse and standardized treatment unavailable. Interestingly, recent knowledge on the mechanisms of lymphangiogenesis may help elucidate the pathophysiology of Gorham disease and lead to novel treatment targets. Here, we discuss our current understanding of Gorham disease, discuss established and emerging therapeutic strategies, and attempt to frame a treatment rationale.

Impaired testicular function after an ifosfamide-containing regimen for pediatric osteosarcoma: a case series and review of the literature.

To assess testicular function after standard dose ifosfamide, we evaluated 6 young adult osteosarcoma survivors (median age at diagnosis, 16.5 y; median follow-up, 4 y) treated with ifosfamide (median dose, 45.5 g/m) as part of a chemotherapy regimen (adriamycin/cisplatin/methotrexate/ifosfamide/± muramyl-tripeptide-phosphatidyl-ethanolamine). Four of 6 survivors (67%) had abnormal semen analysis (2 oligospermic, 2 azoospermic). Of those, 1/4 had reduced testicular volume, and 2/3 elevated FSH levels. All reported adequate sexual function, 6/6 had normal testosterone levels, but 4/6 had elevated LH levels. Ifosfamide exposure in the context of this regimen was associated with a high likelihood of impaired spermatogenesis and Leydig cell insufficiency.

Phenotyping Pain in Patients With Fibrous Dysplasia/McCune-Albright Syndrome.

CONTEXT: Pain is a poorly managed aspect in fibrous dysplasia/McCune-Albright syndrome (FD/MAS) because of uncertainties regarding the clinical, behavioral, and neurobiological underpinnings that contribute to pain in these patients. OBJECTIVE: Identify neuropsychological and neurobiological factors associated with pain severity in FD/MAS. DESIGN: Prospective, single-site study. PATIENTS: Twenty patients with FD/MAS and 16 age-sex matched healthy controls. INTERVENTION: Assessments of pain severity, neuropathic pain, pain catastrophizing (pain rumination, magnification, and helplessness), emotional health, and pain sensitivity with thermal quantitative sensory testing. Central nervous system (CNS) properties were measured with diffusion tensor imaging, structural magnetic resonance imaging, and functional magnetic resonance imaging. MAIN OUTCOME MEASURES: Questionnaire responses, detection thresholds and tolerances to thermal stimuli, and structural and functional CNS properties. RESULTS: Pain severity in patients with FD/MAS was associated with more neuropathic pain quality, higher levels of pain catastrophizing, and depression. Quantitative sensory testing revealed normal detection of nonnoxious stimuli in patients. Individuals with FD/MAS had higher pain tolerances relative to healthy controls. From neuroimaging studies, greater pain severity, neuropathic pain quality, and psychological status of the patient were associated with reduced structural integrity of white matter pathways (superior thalamic radiation and uncinate fasciculus), reduced gray matter thickness (pre-/paracentral gyri), and heightened responses to pain (precentral, temporal, and frontal gyri). Thus, properties of CNS circuits involved in processing sensorimotor and emotional aspects of pain were altered in FD/MAS. CONCLUSION: These results offer insights into pain mechanisms in FD/MAS, while providing a basis for implementation of comprehensive pain management treatment approaches that addresses neuropsychological aspects of pain.

Proton-Based Radiation Therapy for Skull Base Chondrosarcomas in Children and Adolescents: 40-Year Experience From the Massachusetts General Hospital.

PURPOSE: The literature on skull base chondrosarcoma (CHS) is scarce. We report outcomes for pediatric and young patients ≤22 years with base of skull CHSs treated with proton-based radiation therapy (PBRT). METHODS AND MATERIALS: We retrospectively reviewed all patients treated with PBRT between 1981 and 2023. Primary endpoints were overall survival (OS), chondrosarcoma-specific survival (CSS), progression-free survival (PFS), local control, and distal control. RESULTS: Eighty-four patients were identified. Median age at diagnosis was 19 years (range, 6-22). Most patients (n = 79, 94%) had conventional CHS, whereas 5 (6%) had mesenchymal CHS. Nine patients (11%) underwent gross total resection, 64 (76%) subtotal resection, and 11 patients (13%) underwent biopsy. Twenty-four (29%) patients progressed before radiation therapy. The median prescription dose was 70 Gy (relative biological equivalent) (range, 50-79.7). At a median follow-up of 18.0 years (IQR, 9.2-26.2) from diagnosis, 11 patients recurred (7 local, 4 distant). Six patients died of disease. Five patients died of other causes. Ten-year OS, CSS, and PFS rates for all patients were 93.3%, 94.7%, and 88%, respectively. Twenty-year OS, CSS, and PFS rates for conventional CHS (n = 79) were 93.1%, 97.1%, and 89.2%, respectively. Mesenchymal histology was significantly associated with worse OS and PFS. Preradiation therapy tumor progression portended worse OS and CSS. Eight patients (9.9 %) experienced a late toxicity grade 3 or greater. CONCLUSIONS: This is the largest cohort of pediatric base of skull CHSs in literature to date. High-dose PBRT after surgical resection achieves excellent disease control with minimal toxicity.

A dynamic microRNA profile that tracks a chemotherapy resistance phenotype in osteosarcoma. Implications for novel therapeutics.

Osteosarcoma is a rare primary bone tumor for which no significant therapeutic advancement has been made since the late 1980s despite ongoing efforts. Overall, the five-year survival rate remains about 65%, and is much lower in patients with tumors unresponsive to methotrexate, doxorubicin, and cisplatin therapy. Genetic studies have not revealed actionable drug targets, but our group, and others, have reported that epigenomic biomarkers, including regulatory RNAs, may be useful prognostic tools for osteosarcoma. We tested if microRNA (miRNA) transcriptional patterns mark the transition from a chemotherapy sensitive to resistant tumor phenotype. Small RNA sequencing was performed using 14 patient matched pre-chemotherapy biopsy and post-chemotherapy resection high-grade osteosarcoma frozen tumor samples. Independently, small RNA sequencing was performed using 14 patient matched biopsy and resection samples from untreated tumors. Separately, miRNA specific Illumina DASL arrays were used to assay an independent cohort of 65 pre-chemotherapy biopsy and 26 patient matched post-chemotherapy resection formalin fixed paraffin embedded (FFPE) tumor samples. mRNA specific Illumina DASL arrays were used to profile 37 pre-chemotherapy biopsy and five post-chemotherapy resection FFPE samples, all of which were also used for Illumina DASL miRNA profiling. The National Cancer Institute Therapeutically Applicable Research to Generate Effective Treatments dataset, including PCR based miRNA profiling and RNA-seq data for 86 and 93 pre-chemotherapy tumor samples, respectively, was also used. Paired differential expression testing revealed a profile of 17 miRNAs with significantly different transcriptional levels following chemotherapy. Genes targeted by the miRNAs were differentially expressed following chemotherapy, suggesting the miRNAs may regulate transcriptional networks. Finally, an in vitro pharmacogenomic screen using miRNAs and their target transcripts predicted response to a set of candidate small molecule therapeutics which potentially reverse the chemotherapy resistance phenotype and synergize with chemotherapy in otherwise treatment resistant tumors. Importantly, these novel therapeutic targets are distinct from targets identified by a similar pharmacogenomic analysis of previously published prognostic miRNA profiles from pre chemotherapy biopsy specimens.