P Maher

Bio: P Maher is an academic researcher. The author has contributed to research in topics: Kerma & Digital subtraction angiography. The author has an hindex of 1, co-authored 1 publications receiving 312 citations.

Chemotherapy without irradiation--a novel approach for newly diagnosed CNS germ cell tumors: results of an international cooperative trial. The First International Central Nervous System Germ Cell Tumor Study.

Abstract: PURPOSERadiation therapy for CNS germ cell tumors (GCT) is commonly associated with neurologic sequelae. We designed a therapeutic trial to determine whether irradiation could be avoided.PATIENTS AND METHODSPatients received four cycles of carboplatin, etoposide, and bleomycin. Those with a complete response (CR) received two further cycles; others received two cycles intensified by cyclophosphamide.RESULTSSeventy-one patients were enrolled (45 with germinoma and 26 with nongerminomatous GCT [NGGCT]). Sixty-eight were assessable for response. Thirty-nine of 68 (57%) achieved a CR within four cycles. Of 29 patients with less than a CR, 16 achieved CR with intensified chemotherapy or second surgery. Overall, 55 of 71 (78%) achieved a CR without irradiation. The CR rate was 84% for germinomas and 78% for NGGCT. With a median follow-up duration of 31 months, 28 of 71 patients were alive without relapse or progression. Thirty-five showed tumor recurrence (n = 28) or progression (n = 7) at a median of 13 months...

Patient radiation dose during angiography and embolization for abdominal hemorrhage: the influence of CT angiography, fluoroscopy system, patient and procedural variables

Abstract: Angiography and embolization (AE) is a lifesaving, high radiation dose procedure for treatment of abdominal arterial hemorrhage (AAH). Interventional radiologists have utilized pre-procedure CT angiography (CTA) and newer fluoroscopic systems in an attempt to reduce radiation dose and procedure time.To study the factors contributing to the radiation dose of AE for AAH and to compare to the reference standard.This retrospective single-centre observational cohort study identified 154 consecutive AE procedures in 138 patients (median age 65 years; interquartile range 54-77; 103 men) performed with a C-arm fluoroscopic system (Axiom Artis DTA or Axiom Artis Q (Siemens Healthineers)), between January 2010 and December 2017. Parameters analysed included: demographics, fluoroscopy system, bleeding location, body mass index (BMI), preprocedural CT, air kerma-area product (PKA), reference air kerma (Ka,r), fluoroscopy time (FT) and the number of digital subtraction angiography (DSA) runs. Factors affecting dose were assessed using Mann-Whitney U, Kruskal-Wallis one-way ANOVA and linear regression.Patients treated with the new angiographic system (NS) had a median PKA, median Ka,r, Q3 PKA and Q3 Ka,r that were 74% (p < 0.0005), 66%(p < 0.0005), 55% and 52% lower respectively than those treated with the old system (OS). This dose reduction was consistent for each bleeding location (upper GI, Lower GI and extraluminal). There was no difference in PKA (p = 0.452), Ka,r (p = 0.974) or FT (p = 0.179), between those who did (n = 137) or did not (n = 17) undergo pre-procedure CTA. Other factors significantly influencing radiation dose were: patient BMI and number of DSA runs. A multivariate model containing these variables accounts for 15.2% of the variance in Ka,r (p < 0.005) and 45.9% of the variance of PKA (p < 0.005).Radiation dose for AE in AAH is significantly reduced by new fluoroscopic technology. Higher patient body mass index is an independent key parameter affecting patient dose. Radiation dose was not influenced by haemorrhage site or performance of pre-procedure CTA.

The effects of cone-beam computed tomography imaging guidance on patient radiation exposures in trans-arterial chemoembolisation for hepatocellular carcinoma

Abstract: Abstract This study investigated the effects of cone-beam computed tomography (CBCT) guidance in trans-arterial chemoembolisation (TACE) procedures on the number of digital subtraction angiography (DSA) runs acquired and total patient radiation exposure in patients with hepatocellular carcinoma (HCC). A retrospective, analytical cross-sectional, single institution, study was conducted. Dose data were compared across the control (DSA guidance alone) and study (DSA and CBCT guidance) groups. A total of 122 procedures were included within the study. There was a significant reduction in the number of DSA runs (3 vs 5, p < 0.001) and DSA air kerma-area product (PKA) (3077.3 vs 4276.6 μGym2, p = 0.042) for the study group when compared to the control group. Total procedural PKA and total procedural reference air kerma (Ka,r) were shown to be 50 and 73% higher, respectively, for the study group when compared to the control group. CBCT imaging guidance does reduce the number of DSA runs and DSA PKA required to complete the TACE procedure for patients diagnosed with HCC; however, a substantial increase in total procedural PKA is to be expected and it is thus important that this increased dose is carefully considered and justified.

Intracranial Germ Cell Tumors

Abstract: Intracranial germ cell tumors are a heterogeneous group of lesions which occur in children and adults. Within the classification of intracranial germ cell tumors, there are a variety of different tumor types which carry different prognoses. The diagnosis of an intracranial germ cell tumor usually requires histological information, but a subgroup of tumors will secrete specific tumor markers, including α-fetoprotein and β-human chorionic gonadotropin, which may obviate the need for surgical intervention. The management of intracranial germ cell tumors in both children and adults remains unsettled. Germinomas have a good prognosis, as over 90% of patients can be effectively treated with radiation therapy. The dose and volume of radiation therapy needed for disease control is not well established, and controversy exists concerning the need for whole brain or craniospinal radiation therapy for localized tumors. Germinomas are also chemosensitive and recent reports suggest that the dose and volume of radiation therapy required for disease control can be lessened with the addition of adjuvant chemotherapy. The outcome for patients with nongerminomatous germ cell tumors is less favorable. Radiation therapy alone will result in disease control in 40%-60% of patients. The addition of chemotherapy to radiation therapy may improve the rate of survival. The Oncologist 2000;5:312-320

Pediatric central nervous system germ cell tumors: a review.

Abstract: Central nervous system (CNS) germ cell tumors (GCTs) represent approximately 3% of primary pediatric brain tumors and encompass a wide pathologic spectrum. CNS GCTs are most commonly located in the pineal and suprasellar regions of the brain and can be divided into major groups including germinomas and nongerminomatous GCTs (NGGCTs), with teratomas often considered a separate category. The clinical presentation varies by location and size, and it frequently includes endocrine abnormalities, visual changes, and signs of increased intracranial pressure. Neuroimaging studies cannot differentiate GCTs from other tumors, and therefore, the diagnosis usually requires histologic confirmation. The rare exceptions are the cases where characteristic elevations of tumor markers, including alpha-fetoprotein and/or beta-human chorionic gonadotropin are documented in the serum and/or cerebrospinal fluid. In these cases, the imaging findings along with the tumor marker elevation may be diagnostic in themselves without the need for tissue confirmation. Treatment and prognosis differ greatly between groups. Germinomas have a superior prognosis than NGGCTs. Five-year overall survival rates >90% were reported initially with the use of craniospinal irradiation. More recently, the use of chemotherapy in addition to radiation therapy has afforded the ability to decrease the dose and volume of radiation therapy without affecting survival rates. NGGCTs are less radiosensitive than germinomas, but the use of adjuvant chemotherapy has improved survival rates in this group as well. The standard management for CNS GCTs remains controversial. Treatment regimens aimed to improve progression-free and overall survival times are ongoing.

Central Nervous System Tumors

Abstract: Central nervous system tumors are relatively common in the United States, with more than 40,000 cases annually. Although more than half of these tumors are benign, they can cause substantial morbidity. Malignant primary brain tumors are the leading cause of death from solid tumors in children and the third leading cause of death from cancer in adolescents and adults aged 15 to 34 years. Common presenting symptoms include headache, seizures, and altered mental status. Whereas magnetic resonance imaging helps define the anatomic extent of tumor, biopsy is often required to confirm the diagnosis. Treatment depends on the histologic diagnosis. Benign tumors are usually curable with surgical resection or radiation therapy including stereotactic radiation; however, most patients with malignant brain tumors benefit from chemotherapy either at the time of initial diagnosis or at tumor recurrence. Metastases to the brain remain a frequent and morbid complication of solid tumors but are frequently controlled with surgery or radiation therapy. Unfortunately, the mortality rate from malignant brain tumors remains high, despite initial disease control. This article provides an overview of current diagnostic and treatment approaches for patients with primary and metastatic brain tumors.

SIOP CNS GCT 96: Final report of outcome of a prospective, multinational nonrandomized trial for children and adults with intracranial germinoma, comparing craniospinal irradiation alone with chemotherapy followed by focal primary site irradiation for patients with localized disease

Abstract: Germinomas contribute to about 60% of all intracranial germ cell tumors located in the pineal gland, suprasellar region, basal ganglia, and hypothalamus.1 Intracranial germinomas are highly radiosensitive, with a tendency to spread via cerebrospinal fluid (CSF), and systemic craniospinal radiation therapy has been the standard treatment for many decades.2,3 With this treatment approach, the majority of patients have been cured.4 Concerns have long been raised about the potential adverse effects of radiotherapy.4–6 Therefore, other treatment approaches were introduced to evaluate craniospinal irradiation alone, but with reduced doses, compared with previous practice, or chemotherapy either in combination with radiotherapy or alone.7,8 In the German MAKEI 89 trial, 30 Gy were applied to the craniospinal axis (CSI) with an additional tumor boost of 15 Gy.9 With this regimen, 88% of the patients remained relapse-free at 5 years. In 1990, the French Society of Paediatric Oncology initiated a trial using chemotherapy and local field radiotherapy in localized germinomas with favorable results.10 In 1998, Matsutani et al11,12 reported excellent survival for germinomas treated with surgery, followed by extended field or whole brain radiotherapy. Patients who received chemotherapy before reduced radiotherapy (30 Gy) were all alive at a median follow-up of 4.3 years. Aoyama et al13 presented promising excellent results in a second Japanese series including 16 germinomas treated with surgery, followed by chemotherapy and low-dose involved-field radiotherapy. Approaches using chemotherapy alone have not been promising.10 Because of the rarity of the disease, an international prospective study was established in 1996 in Europe to evaluate outcomes in a larger patient cohort. In this trial, the outcomes in patients with histologically proven intracranial germinomas (with or without teratoma) treated either with a reduced dose of 24 Gy CSI and additional boost to the primary and metastatic sites of 16 Gy or with combined treatment were evaluated in a nonrandomized fashion.

Radiation therapy for intracranial germinoma: results of the German cooperative prospective trials MAKEI 83/86/89.

Abstract: PURPOSE: A multicenter prospective trial was conducted (Maligue Keimzelltumoren [MAKEI] 83/86/89) to assess outcome in intracranial germinoma after treatment with radiotherapy alone at reduced doses. PATIENTS AND METHODS: Between 1983 and 1993, 60 patients with histologically (n = 58) or cytologically (n = 2) confirmed germinoma were enrolled onto the study. Patients received radiotherapy alone (craniospinal axis/local boost). In the MAKEI 83/86 study (involving 11 patients), the dose to the craniospinal axis was 36 Gy and the dose to the tumor region was 14 Gy. In the MAKEI 89 study (involving 49 patients), doses were 30 and 15 Gy, respectively. RESULTS: Median patient age was 13 years (range, 6 to 31 years). Complete remission was achieved in all patients. The estimated (Kaplan-Meier) 5-year relapse-free survival rate was 91.0% ± 3.9% at a mean follow-up of 59.5 months (range, 3 to 180 months); the estimated overall survival rate was 93.7% ± 3.6%. Relapse occurred in five patients 10 to 33 months (mean,...