Robert Chen - Academia.edu (original) (raw)

Papers by Robert Chen

Neuro-oncology, Jan 27, 2018

Pediatric central nervous system germ cell tumors (CNSGCTs) are rare and heterogeneous neoplasms,... more Pediatric central nervous system germ cell tumors (CNSGCTs) are rare and heterogeneous neoplasms, which can be divided into germinomas and nongerminomatous germ cell tumors (NGGCTs). NGGCTs are further subdivided into mature teratomas and nongerminomatous malignant GCTs (NGMGCTs). Clinical outcomes suggest that NGMGCTs have poor prognosis and survival and that they require more extensive radiotherapy and adjuvant chemotherapy. However, the mechanisms underlying this difference are still unclear. DNA methylation alteration is generally acknowledged to cause therapeutic resistance in cancers. We hypothesized that the pediatric NGMGCTs exhibit a different genome-wide DNA methylation pattern, which is involved in the mechanism of its therapeutic resistance. We performed methylation and hydroxymethylation DNA immunoprecipitation sequencing, mRNA expression microarray, and small RNA sequencing (smRNA-seq) to determine methylation-regulated genes, including microRNAs (miRNAs). The expressi...

Formosan Journal of Surgery, 2013

Spinal subdural hematoma (SSDH) is a rare but potentially devastating complication of cranial sur... more Spinal subdural hematoma (SSDH) is a rare but potentially devastating complication of cranial surgery. This study presents two cases of SSDH after posterior fossa surgery. The first case was a 44-year-old man who harbored a fourth ventricle metastatic adenocarcinoma, and the second case was a 4-year-old boy with a posterior fossa medulloblastoma. Both patients underwent suboccipital craniotomy, and SSDHs were found postoperatively. The first case underwent an additional lumbar laminectomy due to cauda equina syndrome; the second case received conservative treatment because there were no obvious neurologic deficits. Meticulous hemostasis and the avoidance of cerebrospinal fluid overdrainage may reduce the risk of SSDH after cranial surgery. Emergent decompression is warranted for SSDH in the presence of progressive neurologic deterioration.

Journal of the Chinese Medical Association, 2010

Unsteady gait was noted in a 2-year-old boy with a lumboperitoneal (LP) shunt that had been inser... more Unsteady gait was noted in a 2-year-old boy with a lumboperitoneal (LP) shunt that had been inserted 1 year earlier for increased head circumference caused by communicating hydrocephalus. Scoliosis was also noted during postoperative follow-up. Magnetic resonance imaging revealed new hindbrain tonsillar herniation and an extensive syrinx from C3 to L1. The malfunctioning LP shunt was removed and posterior fossa decompression with ventriculoperitoneal shunt insertion was performed. The unsteady gait recovered completely and scoliosis improved. Magnetic resonance imaging demonstrated resolution of the syrinx and tonsillar herniation. Acquired Chiari I malformation after LP shunt is well documented; usually, patients have no symptoms. This is the first report to have all the cause and effect mechanisms among syringomyelia, scoliosis and Chiari I malformation in 1 patient. We review the literature and discuss the possible mechanisms. [

Journal of the Chinese Medical Association, 2012

Background: We evaluated adverse ischemic events as early surgical results of microsurgical clipp... more Background: We evaluated adverse ischemic events as early surgical results of microsurgical clipping of 44 and 34 posterior communicating artery (PComA) aneurysms through the pterional transsylvian and pretemporal transclinoidal approach, respectively, between January 2007 and October 2010. Methods: Patients undergoing PComA aneurysm clipping were divided into two groups, and their immediate surgical results were compared and analyzed. Those who underwent the pterional transsylvian approach (group A) comprised 42 patients with 44 PComA aneurysms (24 ruptured and 20 unruptured). Those who underwent the pretemporal transclinoidal approach (group B) comprised 32 patients with 34 PComA aneurysms (20 ruptured and 14 unruptured). Results: The immediate postoperative total occlusion rates were 97.7% in group A and 100% in group B. The pretemporal transclinoidal approach significantly reduced the overall risk of silent and symptomatic ischemic strokes (p ¼ 0.04) in ruptured PComA clippings and tended to lower the incidence of intraoperative aneurysm rupture (p ¼ 0.07) as well as the overall ischemic events (p ¼ 0.06) in a total of 78 aneurysm clippings, as compared with the pterional transsylvian approach. Although not significantly, the pretemporal transclinoidal approach also tended to have a lower incidence of intraoperative aneurysm rupture in ruptured aneurysm clippings (p ¼ 0.11), which were mainly responsible for the symptomatic ischemia. The pretemporal transclinoidal approach had no additional advantage over the traditional pterional transsylvian approach in unruptured PComA aneurysm clippings in the present study. Conclusion: The pretemporal transclinoidal approach achieved better visualization of the vital neurovascular structures surrounding PComA aneurysms, which might be a key improvement in lowering the risk of intraoperative aneurysm rupture and obtaining significantly satisfactory immediate surgical results in the microsurgical clipping of PComA aneurysms, especially ruptured ones.

Cancer medicine, Jan 5, 2016

We aimed to investigate the incidence and long-term outcome of moyamoya syndrome in pediatric pat... more We aimed to investigate the incidence and long-term outcome of moyamoya syndrome in pediatric patients with primary brain tumors after receiving cranial radiotherapy (RT) in a single institute in Taiwan. The complete medical records, medical images, and RT notes of 391 pediatric patients with primary brain tumors treated with cranial RT between January 1975 and December 2005 in Taipei Veterans General Hospital (TVGH), Taiwan, were entered into an electronic registry and reviewed. Eight (2%) cases of post-RT moyamoya syndrome were identified in the sample of 391 patients. The median latency was 3 years post-RT. Among the eight patients, three had craniopharyngioma, two had optic glioma, two had medulloblastoma, and one had a suprasellar astrocytoma. The prescribed physical doses of RT were in the range of 40-54 Gy. The incidence was highest in those with optic glioma (0.039/person-year), followed by craniopharyngioma (0.013/person-year), astrocytoma (0.003/person-year), and medullobl...

Neuro-oncology, Jan 11, 2017

Craniopharyngiomas are frequent hypothalamo-pituitary tumors in children, presenting predominantl... more Craniopharyngiomas are frequent hypothalamo-pituitary tumors in children, presenting predominantly as cystic lesions. Morbidity from conventional treatment has focused attention on intracystic drug delivery, hypothesized to cause fewer clinical consequences. However, the efficacy of intracystic therapy remains unclear. We report the retrospective experiences of several global centers using intracystic interferon-alpha. European Société Internationale d'Oncologie Pédiatrique and International Society for Pediatric Neurosurgery centers were contacted to submit a datasheet capturing pediatric patients with cystic craniopharyngiomas who had received intracystic interferon-alpha. Patient demographics, administration schedules, adverse events, and outcomes were obtained. Progression was clinical or radiological (cyst reaccumulation, novel cysts, or solid growth). Fifty-six children (median age, 6.3 y) from 21 international centers were identified. Median follow-up from diagnosis was 5...

Journal of the Chinese Medical Association, 2012

Dural sinus malformation (DSM) is an extremely rare and congenital cerebrovascular malformation t... more Dural sinus malformation (DSM) is an extremely rare and congenital cerebrovascular malformation that is associated with dural arteriovenous fistula and a large dural lake, which may mimic the clinical malformations of an infantile dural arteriovenous shunt or the vein of Galen. Early diagnosis and treatment of DSM is crucial in order to avoid irreversible brain injuries or heart failure. Here, we report an unusual case of extensive DSM that showed good clinical and angiographic results after endovascular embolization.

Biology, 2021

Although boron neutron capture therapy (BNCT) is a promising treatment option for malignant brain... more Although boron neutron capture therapy (BNCT) is a promising treatment option for malignant brain tumors, the optimal BNCT parameters for patients with immediately life-threatening, end-stage brain tumors remain unclear. We performed BNCT on 34 patients with life-threatening, end-stage brain tumors and analyzed the relationship between survival outcomes and BNCT parameters. Before BNCT, MRI and 18F-BPA-PET analyses were conducted to identify the tumor location/distribution and the tumor-to-normal tissue uptake ratio (T/N ratio) of 18F-BPA. No severe adverse events were observed (grade ≥ 3). The objective response rate and disease control rate were 50.0% and 85.3%, respectively. The mean overall survival (OS), cancer-specific survival (CSS), and relapse-free survival (RFS) times were 7.25, 7.80, and 4.18 months, respectively. Remarkably, the mean OS, CSS, and RFS of patients who achieved a complete response were 17.66, 22.5, and 7.50 months, respectively. Kaplan–Meier analysis identi...

Neuro-oncology, Jan 27, 2018

Pediatric central nervous system germ cell tumors (CNSGCTs) are rare and heterogeneous neoplasms,... more Pediatric central nervous system germ cell tumors (CNSGCTs) are rare and heterogeneous neoplasms, which can be divided into germinomas and nongerminomatous germ cell tumors (NGGCTs). NGGCTs are further subdivided into mature teratomas and nongerminomatous malignant GCTs (NGMGCTs). Clinical outcomes suggest that NGMGCTs have poor prognosis and survival and that they require more extensive radiotherapy and adjuvant chemotherapy. However, the mechanisms underlying this difference are still unclear. DNA methylation alteration is generally acknowledged to cause therapeutic resistance in cancers. We hypothesized that the pediatric NGMGCTs exhibit a different genome-wide DNA methylation pattern, which is involved in the mechanism of its therapeutic resistance. We performed methylation and hydroxymethylation DNA immunoprecipitation sequencing, mRNA expression microarray, and small RNA sequencing (smRNA-seq) to determine methylation-regulated genes, including microRNAs (miRNAs). The expressi...

Formosan Journal of Surgery, 2013

Spinal subdural hematoma (SSDH) is a rare but potentially devastating complication of cranial sur... more Spinal subdural hematoma (SSDH) is a rare but potentially devastating complication of cranial surgery. This study presents two cases of SSDH after posterior fossa surgery. The first case was a 44-year-old man who harbored a fourth ventricle metastatic adenocarcinoma, and the second case was a 4-year-old boy with a posterior fossa medulloblastoma. Both patients underwent suboccipital craniotomy, and SSDHs were found postoperatively. The first case underwent an additional lumbar laminectomy due to cauda equina syndrome; the second case received conservative treatment because there were no obvious neurologic deficits. Meticulous hemostasis and the avoidance of cerebrospinal fluid overdrainage may reduce the risk of SSDH after cranial surgery. Emergent decompression is warranted for SSDH in the presence of progressive neurologic deterioration.

Journal of the Chinese Medical Association, 2010

Unsteady gait was noted in a 2-year-old boy with a lumboperitoneal (LP) shunt that had been inser... more Unsteady gait was noted in a 2-year-old boy with a lumboperitoneal (LP) shunt that had been inserted 1 year earlier for increased head circumference caused by communicating hydrocephalus. Scoliosis was also noted during postoperative follow-up. Magnetic resonance imaging revealed new hindbrain tonsillar herniation and an extensive syrinx from C3 to L1. The malfunctioning LP shunt was removed and posterior fossa decompression with ventriculoperitoneal shunt insertion was performed. The unsteady gait recovered completely and scoliosis improved. Magnetic resonance imaging demonstrated resolution of the syrinx and tonsillar herniation. Acquired Chiari I malformation after LP shunt is well documented; usually, patients have no symptoms. This is the first report to have all the cause and effect mechanisms among syringomyelia, scoliosis and Chiari I malformation in 1 patient. We review the literature and discuss the possible mechanisms. [

Journal of the Chinese Medical Association, 2012

Background: We evaluated adverse ischemic events as early surgical results of microsurgical clipp... more Background: We evaluated adverse ischemic events as early surgical results of microsurgical clipping of 44 and 34 posterior communicating artery (PComA) aneurysms through the pterional transsylvian and pretemporal transclinoidal approach, respectively, between January 2007 and October 2010. Methods: Patients undergoing PComA aneurysm clipping were divided into two groups, and their immediate surgical results were compared and analyzed. Those who underwent the pterional transsylvian approach (group A) comprised 42 patients with 44 PComA aneurysms (24 ruptured and 20 unruptured). Those who underwent the pretemporal transclinoidal approach (group B) comprised 32 patients with 34 PComA aneurysms (20 ruptured and 14 unruptured). Results: The immediate postoperative total occlusion rates were 97.7% in group A and 100% in group B. The pretemporal transclinoidal approach significantly reduced the overall risk of silent and symptomatic ischemic strokes (p ¼ 0.04) in ruptured PComA clippings and tended to lower the incidence of intraoperative aneurysm rupture (p ¼ 0.07) as well as the overall ischemic events (p ¼ 0.06) in a total of 78 aneurysm clippings, as compared with the pterional transsylvian approach. Although not significantly, the pretemporal transclinoidal approach also tended to have a lower incidence of intraoperative aneurysm rupture in ruptured aneurysm clippings (p ¼ 0.11), which were mainly responsible for the symptomatic ischemia. The pretemporal transclinoidal approach had no additional advantage over the traditional pterional transsylvian approach in unruptured PComA aneurysm clippings in the present study. Conclusion: The pretemporal transclinoidal approach achieved better visualization of the vital neurovascular structures surrounding PComA aneurysms, which might be a key improvement in lowering the risk of intraoperative aneurysm rupture and obtaining significantly satisfactory immediate surgical results in the microsurgical clipping of PComA aneurysms, especially ruptured ones.

Cancer medicine, Jan 5, 2016

We aimed to investigate the incidence and long-term outcome of moyamoya syndrome in pediatric pat... more We aimed to investigate the incidence and long-term outcome of moyamoya syndrome in pediatric patients with primary brain tumors after receiving cranial radiotherapy (RT) in a single institute in Taiwan. The complete medical records, medical images, and RT notes of 391 pediatric patients with primary brain tumors treated with cranial RT between January 1975 and December 2005 in Taipei Veterans General Hospital (TVGH), Taiwan, were entered into an electronic registry and reviewed. Eight (2%) cases of post-RT moyamoya syndrome were identified in the sample of 391 patients. The median latency was 3 years post-RT. Among the eight patients, three had craniopharyngioma, two had optic glioma, two had medulloblastoma, and one had a suprasellar astrocytoma. The prescribed physical doses of RT were in the range of 40-54 Gy. The incidence was highest in those with optic glioma (0.039/person-year), followed by craniopharyngioma (0.013/person-year), astrocytoma (0.003/person-year), and medullobl...

Neuro-oncology, Jan 11, 2017

Craniopharyngiomas are frequent hypothalamo-pituitary tumors in children, presenting predominantl... more Craniopharyngiomas are frequent hypothalamo-pituitary tumors in children, presenting predominantly as cystic lesions. Morbidity from conventional treatment has focused attention on intracystic drug delivery, hypothesized to cause fewer clinical consequences. However, the efficacy of intracystic therapy remains unclear. We report the retrospective experiences of several global centers using intracystic interferon-alpha. European Société Internationale d'Oncologie Pédiatrique and International Society for Pediatric Neurosurgery centers were contacted to submit a datasheet capturing pediatric patients with cystic craniopharyngiomas who had received intracystic interferon-alpha. Patient demographics, administration schedules, adverse events, and outcomes were obtained. Progression was clinical or radiological (cyst reaccumulation, novel cysts, or solid growth). Fifty-six children (median age, 6.3 y) from 21 international centers were identified. Median follow-up from diagnosis was 5...

Journal of the Chinese Medical Association, 2012

Dural sinus malformation (DSM) is an extremely rare and congenital cerebrovascular malformation t... more Dural sinus malformation (DSM) is an extremely rare and congenital cerebrovascular malformation that is associated with dural arteriovenous fistula and a large dural lake, which may mimic the clinical malformations of an infantile dural arteriovenous shunt or the vein of Galen. Early diagnosis and treatment of DSM is crucial in order to avoid irreversible brain injuries or heart failure. Here, we report an unusual case of extensive DSM that showed good clinical and angiographic results after endovascular embolization.

Biology, 2021

Although boron neutron capture therapy (BNCT) is a promising treatment option for malignant brain... more Although boron neutron capture therapy (BNCT) is a promising treatment option for malignant brain tumors, the optimal BNCT parameters for patients with immediately life-threatening, end-stage brain tumors remain unclear. We performed BNCT on 34 patients with life-threatening, end-stage brain tumors and analyzed the relationship between survival outcomes and BNCT parameters. Before BNCT, MRI and 18F-BPA-PET analyses were conducted to identify the tumor location/distribution and the tumor-to-normal tissue uptake ratio (T/N ratio) of 18F-BPA. No severe adverse events were observed (grade ≥ 3). The objective response rate and disease control rate were 50.0% and 85.3%, respectively. The mean overall survival (OS), cancer-specific survival (CSS), and relapse-free survival (RFS) times were 7.25, 7.80, and 4.18 months, respectively. Remarkably, the mean OS, CSS, and RFS of patients who achieved a complete response were 17.66, 22.5, and 7.50 months, respectively. Kaplan–Meier analysis identi...