Conformal radiation therapy for childhood CNS tumors

Radiotherapy for Primary Pediatric Central Nervous System Malignancies: Current Treatment Paradigms and Future Directions

BACKGROUND

Central nervous system tumors are the most common solid tumors in childhood. Treatment paradigms for pediatric central nervous system malignancies depend on elements including tumor histology, age of patient, and stage of disease. Radiotherapy is an important modality of treatment for many pediatric central nervous system malignancies.

SUMMARY

While radiation contributes to excellent overall survival rates for many patients, radiation also carries significant risks of long-term side effects including neurocognitive decline, hearing loss, growth impairment, neuroendocrine dysfunction, strokes, and secondary malignancies. In recent decades, clinical trials have demonstrated that with better imaging and staging along with more sophisticated radiation planning and treatment set-up verification, smaller treatment volumes can be utilized without decrement in survival. Furthermore, the development of intensity-modulated radiotherapy and proton-beam radiotherapy has greatly improved conformality of radiation.

KEY MESSAGES

Recent changes in radiation treatment paradigms have decreased risks of short- and long-term toxicity for common histologies and in different age groups. Future studies will continue to develop novel radiation regimens to improve outcomes in aggressive central nervous system tumors, integrate molecular subtypes to tailor radiation treatment, and decrease radiation-associated toxicity for long-term survivors.

Development and Quality Assurance of Multileaf Collimator (MLC) Auto-Feathering Junctions for Multi-Isocenter Supine Volumetric Modulated Arc Therapy (VMAT) Craniospinal Axis Irradiation on Halcyon

Currently, there is a lack of methods and tools that efficiently evaluate the auto-feathering junctions created by multileaf collimator (MLCs) for supine volumetric modulated arc therapy (VMAT) craniospinal irradiation (CSI) plans. We have investigated the feasibility of stitching together multi-isocenter fluence maps to then analyze the feathered junctions for patient-specific quality assurance (QA). Furthermore, we investigated the capability of Halcyon for the treatment of CSI patients. Three patients, who previously underwent VMAT CSI treatment on TrueBeam (6-MV flattening filter-free (FFF)) for 36 Gy in 20 fractions were replanned for Halcyon. A multi-isocenter approach with only translational superior-inferior shifts was used for both platforms. Each isocenter consists of two full arcs with anterior avoidance sectors, ±5° collimator rotations between arcs, and 5-8 cm of overlapping MLC auto-feathering junctions. All plans were QA'd via electronic portal imaging device (EPID) portal dosimetry and analyzed with a gamma criteria of 3%/3 mm. A variety of plan quality metrics were analyzed to evaluate dose distributions to the target, doses to organs at risk (OARs), and integral dose to the patient. A MATLAB script was developed to stitch the calculated and measured fluence maps in order to perform patient-specific QA for the composite fluence. The Halcyon plans provided highly conformal and homogenous dose distributions to the entire CSI target, superior to the clinical TrueBeam plans, while sparing critical organs with significantly lower values of V10Gy and V18Gy by up to 2% and 2.5%, respectively. Qualitative depictions of vertical dose profiles from the stitched DICOM of the entire CSI target for both planned and delivered fluence maps demonstrated equivalency, with slightly lower average pass rates with Halcyon (97%) compared to TrueBeam (99.9%). This approach to stitch multiple measured versus calculated EPID fluence maps has shown to be a feasible and accurate method and will be helpful for comprehensive VMAT CSI QA on both platforms. Further implementation of this script will be used in examining dosimetric impacts of daily patient positioning errors at MLC auto-feathering junctions.

Pediatric Craniospinal Irradiation - The implementation and Use of Normal Tissue Complication Probability in Comparing Photon versus Proton Planning

Purpose:

The preferred radiotherapy treatment for medulloblastoma is craniospinal irradiation (CSI). With the aim of developing the potential to reduce normal tissue dose and associated post-treatment complications with photon and proton radiotherapy techniques for CSI. This report aims to carefully compare and rank treatment planning and dosimetric outcomes for pediatric medulloblastoma patients using normal tissue complication probability (NTCP) formalism between photon (three-dimensional conformal radiotherapy, intensity-modulated radiotherapy [IMRT], volumetric-modulated arc therapy [VMAT], and HT) and proton CSI.

Methods and Materials:

The treatment data of eight pediatric patients who typically received CSI treatment were used in this study. The patients were 7 years of age on average, with ages ranging from 3 to 11 years. A prescription dose of 3600 cGy was delivered in 20 fractions by the established planning methods. The Niemierko's and Lyman–Kutcher–Burman models were followed to carefully estimate NTCP and compare different treatment plans.

Results:

The NTCP of VMAT plans in upper and middle thoracic volumes was relatively high compared to helical tomotherapy (HT) and pencil beam scanning (PBS) (all P < 0.05). PBS rather than IMRT and VMAT in the middle thoracic region (P < 0.06) could significantly reduce the NTCP of the heart. PBS significantly reduced NTCP of the lungs and liver (all P < 0.05).

Conclusion:

The NTCP and tumor control probability (TCP) model-based plan ranking along with dosimetric indices will help the clinical practitioner or medical physicists to choose the best treatment plan for each patient based on their anatomical or clinical challenges.

A comparative study on dispersed doses during photon and proton radiation therapy in pediatric applications

The Monte Carlo method was employed to simulate realistic treatment situations for photon and proton radiation therapy for a set of Oak Ridge National Laboratory (ORNL) pediatric phantoms for 15, 10, 5 and 1-year olds as well as newborns. Complete radiotherapy situations were simulated using the previously developed NRUrad input code for Monte Carlo N-Particle (MCNP) code package. Each pediatric phantom was irradiated at five different positions, namely, the testes, colon, liver, left lung and brain, and the doses in targeted organs (Dt) were determined using the track length estimate of energy. The dispersed photon and proton doses in non-targeted organs (Dd), namely, the skeleton, skin, brain, spine, left and right lungs were computed. The conversion coefficients (F = Dd/Dt) of the dispersed doses were used to study the dose dispersion in different non-targeted organs for phantoms for 15, 10, 5 and 1-year olds as well as newborns. In general, the F values were larger for younger patients. The F values for non-targeted organs for phantoms for 1-year olds and newborns were significantly larger compared to those for other phantoms. The dispersed doses from proton radiation therapy were also found to be significantly lower than those from conventional photon radiation therapy. For example, the largest F values for the brain were 65.6% and 0.206% of the dose delivered to the left lung (P4) for newborns during photon and proton radiation therapy, respectively. The present results demonstrated that dispersion of photons and generated electrons significantly affected the absorbed doses in non-targeted organs during pediatric photon therapy, and illustrated that proton therapy could in general bring benefits for treatment of pediatric cancer patients.

Psychosocial Support for Pediatric Patients at Proton Therapy Institutions

Purpose

Pediatric patients with cancer benefit significantly from psychosocial support during and after treatment, but to date, limited data exist regarding the patterns of psychosocial support provided to patients in radiation oncology departments. The purpose of this study was to assess the supportive care services provided at proton therapy institutions in the United States with a specific focus on education, parental involvement, and coping techniques.

Materials and Methods

Physicians, nurses, and child life specialists at 29 operational proton therapy facilities in the United States were sent an online questionnaire regarding pediatric treatment support. The survey consisted of 10 questions exploring strategies employed to educate and support pediatric patients before and during radiotherapy.

Results

Staff members from 23 of 29 operational proton centers (79%) in the United States completed the survey. Three centers (10%) declined to participate, and three (10%) did not complete the questionnaire. Respondents permitted parental presence for body positioning on the first day of treatment and every day of treatment if needed at 95.6% (22 of 23) and 73.9% (17 of 23) of the centers, respectively. Primary education methods included a facility tour (91.3%; 21 of 23) and psychological preparation (78.3%; 17 of 23). Physicians (82.6%; 19 of 23), nurses (73.9%; 17 of 23), and child life specialists (69.6%; 16 of 23) most commonly provided education to pediatric patients and their families. Only 21.7% (5 of 23) of the facilities reported documentation of a psychosocial support policy. Common coping techniques included music (87.0%; 20 of 23), parental presence for positioning (73.9%; 17 of 23), listening to audio recordings (73.9%; 17 of 23), aromatherapy on or near the patient (73.9%; 17 of 23), and use of a stress ball (65.2%; 15 of 23).

Conclusion

Proton therapy institutions frequently offered psychologic preparation before treatment and employed various coping strategies. Based on this survey, we propose several recommendations to raise awareness and improve the experience of pediatric patients at radiation oncology centers.

Discrepancies among Measures of Executive Functioning in a Subsample of Young Adult Survivors of Childhood Brain Tumor: Associations with Treatment Intensity

OBJECTIVES

Treatments for childhood brain tumors (BT) confer substantial risks to neurological development and contribute to neuropsychological deficits in young adulthood. Evidence suggests that individuals who experience more significant neurological insult may lack insight into their neurocognitive limitations. The present study compared survivor, mother, and performance-based estimates of executive functioning (EF), and their associations with treatment intensity history in a subsample of young adult survivors of childhood BTs.

METHODS

Thirty-four survivors (52.9% female), aged 18 to 30 years (M=23.5; SD=3.4), 16.1 years post-diagnosis (SD=5.9), were administered self-report and performance-based EF measures. Mothers also rated survivor EF skills. Survivors were classified by treatment intensity history into Minimal, Average/Moderate, or Intensive/Most-Intensive groups. Discrepancies among survivor, mother, and performance-based EF estimates were compared.

RESULTS

Survivor-reported and performance-based measures were not correlated, although significant associations were found between mother-reported and performance measures. Survivors in the Intensive/Most-Intensive treatment group evidenced the greatest score discrepancies, reporting less executive dysfunction relative to mother-reported F(2,31)=7.81, p.05).

CONCLUSIONS

There may be a lack of agreement among survivor, mother, and performance-based estimates of EF skills in young adult survivors of childhood BT, and these discrepancies may be associated with treatment intensity history. Neuropsychologists should use a multi-method, multi-reporter approach to assessment of EF in this population. Providers also should be aware of these discrepancies as they may be a barrier to intervention efforts. (JINS, 2016, 22, 900-910).

Ion mobility-enhanced MS(E)-based label-free analysis reveals effects of low-dose radiation post contextual fear conditioning training on the mouse hippocampal proteome

Recent advances in the field of biodosimetry have shown that the response of biological systems to ionizing radiation is complex and depends on the type and dose of radiation, the tissue(s) exposed, and the time lapsed after exposure. The biological effects of low dose radiation on learning and memory are not well understood. An ion mobility-enhanced data-independent acquisition (MS(E)) approach in conjunction with the ISOQuant software tool was utilized for label-free quantification of hippocampal proteins with the goal of determining protein alteration associated with low-dose whole body ionizing radiation (X-rays, 1Gy) of 5.5-month-old male C57BL/6J mice post contextual fear conditioning training. Global proteome analysis revealed deregulation of 73 proteins (out of 399 proteins). Deregulated proteins indicated adverse effects of irradiation on myelination and perturbation of energy metabolism pathways involving a shift from the TCA cycle to glutamate oxidation. Our findings also indicate that proteins associated with synaptic activity, including vesicle recycling and neurotransmission, were altered in the irradiated mice. The elevated LTP and decreased LTD suggest improved synaptic transmission and enhanced efficiency of neurotransmitter release which would be consistent with the observed comparable contextual fear memory performance of the mice following post-training whole body or sham-irradiation.

SIGNIFICANCE

This study is significant because the biological consequences of low dose radiation on learning and memory are complex and not yet well understood. We conducted a IMS-enhanced MS(E)-based label-free quantitative proteomic analysis of hippocampal tissue with the goal of determining protein alteration associated with low-dose whole body ionizing radiation (X-ray, 1Gy) of 5.5-month-old male C57BL/6J mice post contextual fear conditioning training. The IMS-enhanced MS(E) approach in conjunction with ISOQuant software was robust and accurate with low median CV values of 0.99% for the technical replicates of samples from both the sham and irradiated group. The biological variance was as low as 1.61% for the sham group and 1.31% for the irradiated group. The applied data generation and processing workflow allowed the quantitative evaluation of 399 proteins. The current proteomic analysis indicates that myelination is sensitive to low dose radiation. The observed protein level changes imply modulation of energy metabolism pathways in the radiation exposed group, specifically changes in protein abundance levels suggest a shift from TCA cycle to glutamate oxidation to satisfy energy demands. Most significantly, our study reveals deregulation of proteins involved in processes that govern synaptic activity including enhanced synaptic vesicle cycling, and altered long-term potentiation (LTP) and depression (LTD). An elevated LTP and decreased LTD suggest improved synaptic transmission and enhanced efficiency of neurotransmitter release which is consistent with the observed comparable contextual fear memory performance of the mice following post-training whole body or sham-irradiation. Overall, our results underscore the importance of low dose radiation experiments for illuminating the sensitivity of biochemical pathways to radiation, and the modulation of potential repair and compensatory response mechanisms. This kind of studies and associated findings may ultimately lead to the design of strategies for ameliorating hippocampal and CNS injury following radiation exposure as part of medical therapies or as a consequence of occupational hazards.

Secondary Neutron Doses to Pediatric Patients During Intracranial Proton Therapy: Monte Carlo Simulation of the Neutron Energy Spectrum and its Organ Doses

Proton therapy has the physical advantage of a Bragg peak that can provide a better dose distribution than conventional x-ray therapy. However, radiation exposure of normal tissues cannot be ignored because it is likely to increase the risk of secondary cancer. Evaluating secondary neutrons generated by the interaction of the proton beam with the treatment beam-line structure is necessary; thus, performing the optimization of radiation protection in proton therapy is required. In this research, the organ dose and energy spectrum were calculated from secondary neutrons using Monte Carlo simulations. The Monte Carlo code known as the Particle and Heavy Ion Transport code System (PHITS) was used to simulate the transport proton and its interaction with the treatment beam-line structure that modeled the double scattering body of the treatment nozzle at the National Cancer Center Hospital East. The doses of the organs in a hybrid computational phantom simulating a 5-y-old boy were calculated. In general, secondary neutron doses were found to decrease with increasing distance to the treatment field. Secondary neutron energy spectra were characterized by incident neutrons with three energy peaks: 1×10, 1, and 100 MeV. A block collimator and a patient collimator contributed significantly to organ doses. In particular, the secondary neutrons from the patient collimator were 30 times higher than those from the first scatter. These results suggested that proactive protection will be required in the design of the treatment beam-line structures and that organ doses from secondary neutrons may be able to be reduced.

Secondary neutron doses received by paediatric patients during intracranial proton therapy treatments

This paper's goal is to assess secondary neutron doses received by paediatric patients treated for intracranial tumours using a 178 MeV proton beam. The MCNPX Monte Carlo model of the proton therapy facility, previously validated through experimental measurements for both proton and neutron dosimetry, was used. First, absorbed dose was calculated for organs located outside the clinical target volume using a series of hybrid computational phantoms for different ages and considering a realistic treatment plan. In general, secondary neutron dose was found to decrease as the distance to the treatment field increases and as the patient age increases. In addition, secondary neutron doses were studied as a function of the beam incidence. Next, neutron equivalent dose was assessed using organ-specific energy-dependent radiation weighting factors determined from Monte Carlo simulations of neutron spectra at each organ. The equivalent dose was found to reach a maximum value of ∼155 mSv at the level of the breasts for a delivery of 49 proton Gy to an intracranial tumour of a one-year-old female patient. Finally, a thorough comparison of the calculation results with published data demonstrated the dependence of neutron dose on the treatment configuration and proved the need for facility-specific and treatment-dependent neutron dose calculations.

Long-term outcome of centrally located low-grade glioma in children

BACKGROUND

Optimal management of children with centrally located low-grade glioma (LGG) is unclear. Initial interventions in most children are chemotherapy in younger and radiation therapy (RT) in older children. A better understanding of the inherent risk factors along with the effects of interventions on long-term outcome can lead to reassessment of the current approaches to minimize long-term morbidity.

METHODS

To reassess the current treatment strategies of centrally located LGG, we compared the long-term survival and morbidity of different treatment regimens. Medical records of patients primarily treated at Texas Children's Cancer and Hematology Centers between 1987 and 2008 were reviewed.

RESULTS

Forty-seven patients with a median follow-up of 79 months were included in the analysis. The 5-year overall survival and progression-free survival (PFS) for all patients were 96% and 53%, respectively. The 5-year PFS for those treated initially with RT (12 patients; median age, 11 years [range, 3-15 years]) and with chemotherapy (28 patients; median age, 2 years [range 0-8 years]) were 76% and 37%, respectively (log-rank test P = .02). Among children who progressed after chemotherapy, the 5-year PFS after salvage RT was 55%. Patients diagnosed at a younger age (<5 years) were more likely to experience endocrine abnormalities (Fisher exact test; P<.00001).

CONCLUSIONS

Effective and durable tumor control was obtained with RT as initial treatment. In younger patients, chemotherapy can delay the use of RT; however, frequent progression and long-term morbidity are common. More effective and less toxic therapies are required in these patients, the majority of whom are long-term survivors.

Impact of proton beam availability on patient treatment schedule in radiation oncology

Proton beam therapy offers unique physical properties with potential for reduced toxicity and better patient care. There is an increased interest in radiation oncology centers to acquire proton therapy capabilities. The operation of a proton treatment center is quite different than a photon‐based clinic because of the more complex technology involved, as well as the single proton beam source serving multiple treatment rooms with no backup source available. There is limited published data which investigates metrics that can be used to determine the performance of a proton facility. The purpose of this study is to evaluate performance metrics of Indiana University Cyclotron Operations (IUCO), including availability, mean time between failures, and mean time to repair, and to determine how changes in these metrics impact patient treatments. We utilized a computerized maintenance management system to log all downtime occurrences and servicing operations for the facility. These data were then used to calculate the availability as well as the mean time between failures and mean time to repair. Impact on patient treatments was determined by analyzing delayed and missed treatments, which were recorded in an electronic medical record and database maintained by the therapists. The availability of the IUCO proton beam has been increasing since beginning of operation in 2003 and averaged 96.9% for 2009 through 2011. The mean time between failures and mean time to repair were also determined and correlated with improvements in the maintenance and operating procedures of the facility, as well as environmental factors. It was found that events less than 15 minutes in duration have minimal impact on treatment delays, while events lasting longer than one hour may result in missed treatments. The availability of the proton beam was more closely correlated with delayed than with missed treatments, demonstrating the utility and limitations of the availability metric. In conclusion, we suggest that the availability metric and other performance parameters, such as the mean time between failures and the mean time to repair, should be used in combination with downtime impact on patient treatments in order to adequately evaluate the operational success of a proton therapy facility.

PACS number: 87.55.‐x

Neurocognitive dysfunction in survivors of childhood brain tumors

Newer treatments have resulted in increasing numbers of survivors of childhood cancer, for whom neurological and neurocognitive toxicity directly impacts overall functioning and quality of life. There are multiple disease- and host-related factors that influence the development of cancer-related neurocognitive dysfunction, which can progress over time and lead to significant functional impairments. This article provides an overview of the types of neurocognitive deficits seen in survivors of childhood brain tumors, the tools used to assess neurocognitive function, and the factors that impact its severity. This provides a framework for consideration of potential areas for primary prevention by reducing treatment-related toxicity as well as interventions, using behavioral and pharmacologic treatments.

Annual report to the nation on the status of cancer, 1975-2007, featuring tumors of the brain and other nervous system

Background

The American Cancer Society, the Centers for Disease Control and Prevention (CDC), the National Cancer Institute, and the North American Association of Central Cancer Registries (NAACCR) collaborate annually to provide updated information on cancer occurrence and trends in the United States. This year’s report highlights brain and other nervous system (ONS) tumors, including nonmalignant brain tumors, which became reportable on a national level in 2004.

Methods

Cancer incidence data were obtained from the National Cancer Institute, CDC, and NAACCR, and information on deaths was obtained from the CDC’s National Center for Health Statistics. The annual percentage changes in age-standardized incidence and death rates (2000 US population standard) for all cancers combined and for the top 15 cancers for men and for women were estimated by joinpoint analysis of long-term (1992–2007 for incidence; 1975–2007 for mortality) trends and short-term fixed interval (1998–2007) trends. Analyses of malignant neuroepithelial brain and ONS tumors were based on data from 1980–2007; data on nonmalignant tumors were available for 2004–2007. All statistical tests were two-sided.

Results

Overall cancer incidence rates decreased by approximately 1% per year; the decrease was statistically significant (P < .05) in women, but not in men, because of a recent increase in prostate cancer incidence. The death rates continued to decrease for both sexes. Childhood cancer incidence rates continued to increase, whereas death rates continued to decrease. Lung cancer death rates decreased in women for the first time during 2003–2007, more than a decade after decreasing in men. During 2004–2007, more than 213 500 primary brain and ONS tumors were diagnosed, and 35.8% were malignant. From 1987–2007, the incidence of neuroepithelial malignant brain and ONS tumors decreased by 0.4% per year in men and women combined.

Conclusions

The decrease in cancer incidence and mortality reflects progress in cancer prevention, early detection, and treatment. However, major challenges remain, including increasing incidence rates and continued low survival for some cancers. Malignant and nonmalignant brain tumors demonstrate differing patterns of occurrence by sex, age, and race, and exhibit considerable biologic diversity. Inclusion of nonmalignant brain tumors in cancer registries provides a fuller assessment of disease burden and medical resource needs associated with these unique tumors.

Proton therapy for cancer treatment

Proton beam therapy is the latest advancement in the treatment of various types of cancer. It is a precise form of radiotherapy. It uses a beam of protons to target the cancer cells and destroys them. It scores high on precision and effectiveness when compared to other conventional cancer treatments like surgery, chemotherapy and xray radiotherapy. Proton beam therapy destroys the cancerous cells without harming the healthy cells. Thus it considerably reduces the side-effects that accompany conventional cancer treatments. Supporters say the technology allows physicians to treat a broad spectrum of cancers with few adverse effects, while more precisely targeting tumor cells with higher doses of radiation. Detractors say proton beam therapy is hugely expensive and has not been shown to be superior to conventional radiation treatment. With proton beam therapy, physicians use a cyclotron to accelerate protons and fire them directly into tumor cells with submillimeter precision. Because healthy tissue is largely spared, oncologists can, in theory, deliver much higher doses of radiation, while improving local control and reducing the risk for recurrence and morbidities.

Radiation therapy in paediatric gliomas: our institutional experience

BACKGROUND AND PURPOSE

The aim of our retrospective study was to analyze the clinical outcome of paediatric glioma patients treated with radiation therapy (RT) in our institution.

MATERIAL AND METHODS

We retrieved the case records of all children with gliomas (age < 18 years) who received RT in our department between 2004 and 2007. We analyzed the information regarding patients' demography, clinical details, treatment given, RT details, and survival. The event-free survival (EFS), the period from the date of completion of RT to the date of the event, i.e. death/recurrence, was calculated with respect to age, sex, location of tumour (brainstem vs. non-brainstem), histopathology (low grade vs. high grade), extent of surgical resection, dose and duration of RT, and use of chemotherapy.

RESULTS

A total of 70 children with glioma received RT during the above-mentioned period. The 3-year EFS rate for all patients was 44% and the median EFS period was 18 months. The 3-year EFS in patients who underwent surgical decompression and no surgery was 58% and 25%, respectively (p < 0.05). Patients with brainstem lesions had statistically significantly lower 3-year EFS to non-brainstem gliomas (28% vs. 56%, p < 0.01). Chemotherapy use showed no statistically significant trend towards better survival.

CONCLUSIONS

RT is an effective modality of treatment in paediatric glioma patients in our setup. Early use of RT in incompletely resected low-grade gliomas is worth revisit-ing. Results of chemotherapy in high-grade glioma and brainstem gliomas are encouraging.

Anesthetic considerations for the pediatric oncology patient--part 1: a review of antitumor therapy

The anesthesiologist who cares for children with cancer or for survivors of childhood cancer should possess a basic understanding of cancer treatment. While this is an ever-changing field, a basic knowledge of chemotherapeutic drugs, radiation therapy, and the toxicities of each is necessary to prepare a safe anesthetic plan. Such an understanding also assists the anesthesiologist as the perioperative specialist for these children in consultation with the surgeon and oncologist. This article, which is the first of a three-part review series, will review current principles of cancer therapy and the general mechanisms of toxicity to the child. Although this article is not intended to comprehensively review the fundamentals of chemotherapy and radiation therapy, the consequences of anticancer therapy that impact perioperative care and decision making are presented for the anesthesiologist.

Proton beam radiation therapy in the treatment of pediatric central nervous system malignancies: a review of the literature

One of 5 pediatric cancers occurs within the central nervous system. Although outcomes have improved, the greatest challenge with these patients remains the balance between cure and long-term morbidity. Patients who have undergone radiation therapy remain at high risk for developing a multitude of severe long-term sequelae. As radiation therapy remains a mainstay of treatment much attention has gone into improving its quality and precision. Multiple options exist for these patients, including conventional photon radiotherapy, conformal radiation, and now, proton beam radiotherapy. Proton beams are able to provide utmost precision for targeting the site of the tumor while decreasing radiation doses to surrounding tissues. Studies are showing that the benefits of proton therapy surpass both conventional radiation as well as conformal radiation therapy, and as a result medical centers around the United States are working to open more facilities and improve patient access. As research becomes more readily available and new centers open, pediatric patients will have the option to be treated with this technology in order to preserve cognitive function and decrease long-term effects.

Preventing neurocognitive late effects in childhood cancer survivors

Neurocognitive late effects are common sequelae of cancer in children, especially in those who have undergone treatment for brain tumors or in those receiving prophylactic cranial radiation therapy to treat leukemia. Neurocognitive morbidity in attention, executive functioning, processing speed, working memory, and memory frequently occurs and contributes to declines in intellectual and academic abilities. Oncologists are faced with the challenge of using the most effective, often the most intense, therapy to achieve the primary goal of medical success, balanced with the desire to prevent adverse late effects. Not all children with similar diagnoses and treatment have identical neurocognitive outcomes; some do very poorly and some do well. Attention now turns to the reliable prediction of risk for poor outcomes and then, using risk-adapted therapy, to preserve neurocognitive function. Prevention of late effects through rehabilitative strategies, continuation of school, and pharmacotherapy will be explored.

Congenital brain tumors: case series and review of the literature

Congenital brain tumors are rare and make up only 2% of all pediatric central nervous system tumors. We present 12 cases of congenital brain tumors of various histopathologies. Most of these tumors were of astrocytic lineage. One patient was diagnosed before birth with prenatal ultrasound, but the rest were diagnosed after birth owing to increased head circumference. Four patients received adjuvant chemotherapy after surgery. None received radiation therapy. Seven out of 12 (58%) are long-term survivors. Four of these survivors (57%) have significant neurocognitive or psychomotor impairment. Although rare, congenital brain tumors are one of the more common tumors presenting in the perinatal period and generally carry a poor prognosis. Novel therapies are needed to improve efficacy and decrease the devastating side effects of treatment in this age group.

Intimal Sarcoma of Aortic Arch Treated with Proton Therapy following Surgery

Management of a rare case of intimal sarcoma of the aortic arch is reported, which was diagnosed unexpectedly after total arch replacement for pseudoaneurysm. The prognosis for this condition is poor, with death usually within a few months from diagnosis. The newly developed proton-beam radiation therapy was applied to treat a local recurrence of the sarcoma following surgery. Positron-emission tomography/computed tomography revealed complete remission of the lesion.

What are the potential benefits and limitations of particle therapy in the treatment of paediatric malignancies?

The reduction in dose received by normal tissue is essential in radiotherapy to reduce the chance of late side-effects. This is especially true in paediatric radiotherapy as any late-effects can seriously impair the future quality of life experienced by the treated child.

Particle therapy uses high-energy particles to deliver a surgically precise beam of energy to a pre-determined position in the body. Common side-effects associated with conventional radiotherapy (CRT) are considerably reduced, often virtually eliminated, owing to the reduction in dose received by neighbouring healthy tissues, improving future quality of life. The superior accuracy of particles also means the dose can be escalated improving control rates.

Clinical trials, reviews and planning studies have been reviewed to assess the benefits and limitations offered by particle therapy in paediatric treatments. The reduced integral dose and improved conformity is clearly highlighted throughout these studies, demonstrating the potential advantages available with particles when treating paediatric patients.

The data suggest that the advantages experienced with particle therapy result in a significant reduction in the side-effects experienced and therefore an improvement in quality of life when compared with conventional therapy. Owing to the reduction of subsequent sequelae, paediatric patients need to be considered when designing and constructing a particle centre in the UK.

Conformal therapy improves the therapeutic index of patients with anal canal cancer treated with combined chemotherapy and external beam radiotherapy

PURPOSE

To evaluate the clinical outcomes of three-dimensional conformal radiotherapy (3D-CRT) in patients with anal canal cancer, in terms of local control (LC), freedom from relapse (FFR), and overall survival (OS) rates, and to estimate long-term toxicity data.

METHODS AND MATERIALS

Sixty historical patients, treated with conventional radiation techniques (C-RT), were used as controls, and 62 consecutive patients were treated with 3D-CRT. Patients treated with 3D-CRT received 54 Gy in 30 fractions delivered continuously, compared with 45-58.9 Gy (median dose, 54 Gy) in a split course in patients treated with C-RT. Chemotherapy consisted of 5-fluorouracil with either mitomycin-C or cis-platinum given concurrently with radiation. Survival curves were performed using the Kaplan-Meier model, and the Cox proportional hazards model was used for multivariate analysis of risk factors.

RESULTS

No differences in stage and age distribution were observed between the two groups. Patients treated with 3D-CRT and C-RT had an actuarial 5-year LC rate of 85.1% and 61.1%, respectively (p = 0.0056); the FFR rate was 70.2% and 46.1% (p = 0.0166), and the OS rate was 80.7% and 53.9% (p = 0.0171). In multivariate analysis, factors of significance for LC were nodal (N) status (p < 0.001); for OS, 3D-CRT (p = 0.038), N status (p = 0.011), and T status (p = 0.012); and for FFR, 3D-CRT (p = 0.024) and N status (p < 0.001).

CONCLUSION

The use of 3D-CRT allows patients with anal canal cancer to complete radiation and chemotherapy without interruption for toxicity, with significant improvements in LC, FFR, and OS.

Sensitivity of anterior pituitary hormones to irradiation

Cranial irradiation is used in the management of a diverse group of intracranial pathologies. However, if any part of the hypothalamic-pituitary axis is included in the radiation field, there is a risk of developing neuroendocrine dysfunction. Growth hormone is the most radiosensitive of the anterior pituitary hormones, followed by the gonadotropins, adrenocorticotropic hormone and thyroid-stimulating hormone. A number of factors determine both the occurrence and severity of hypothalamic-pituitary dysfunction, including: the dose of radiation received by the hypothalamic-pituitary axis (determined by a number of factors including total dose and fractionation schedule and ultimately expressed as the biological effective dose); length of time since cranial irradiation; age of the patient at the time of cranial irradiation; type of radiotherapy administered; and the different inherent radiosensitivities of the anterior pituitary hormones. These neuroendocrine abnormalities usually develop a number of years after the initial insult and, therefore, patients who have received cranial irradiation should receive annual endocrine assessments. The establishment of endocrine late-effect clinics for the survivors of childhood cancers have gone some way to addressing this problem; however, other groups of patients, particularly those receiving cranial irradiation in adult life, may not have systematic endocrine assessment.

Brain tumors in children: evaluation and management

Brain and spinal cord tumors represent the most common solid tumors in children. Recent advances in imaging techniques, neurosurgical techniques, chemotherapy approaches, and radiation oncology have resulted in some improvement in overall survival and morbidity. However, the prognosis for many children with high-grade and malignant brain tumors remains guarded in terms of mortality and long-term sequelae. Given the rarity of tumors in children, patients are likely best served at tertiary center that can offer a comprehensive multidiscipline approach.