Proton radiotherapy in management of pediatric base of skull tumors

Proton Therapy in Non-Rhabdomyosarcoma Soft Tissue Sarcomas of Children and Adolescents

This paper provides insights into the use of Proton Beam Therapy (PBT) in pediatric patients with non-rhabdomyosarcoma soft tissue sarcomas (NRSTS). NRSTS are a heterogeneous group of rare and aggressive mesenchymal extraskeletal tumors, presenting complex and challenging clinical management scenarios. The overall survival rate for patients with NRSTS is around 70%, but the outcome is strictly related to the presence of various variables, such as the histological subtype, grade of malignancy and tumor stage at diagnosis. Multimodal therapy is typically considered the preferred treatment for high-grade NRSTS. Radiotherapy plays a key role in the treatment of children and adolescents with NRSTS. However, the potential for radiation-induced side effects partially limits its use. Therefore, PBT represents a very suitable therapeutic option for these patients. The unique depth-dose characteristics of protons can be leveraged to minimize doses to healthy tissue significantly, potentially allowing for increased tumor doses and enhanced preservation of surrounding tissues. These benefits suggest that PBT may improve local control while reducing toxicity and improving quality of life. While clear evidence of therapeutic superiority of PBT over other modern photon techniques in NRSTS is still lacking-partly due to the limited data available-PBT can be an excellent treatment option for young patients with these tumors. A dedicated international comprehensive collaborative approach is essential to better define its role within the multidisciplinary management of NRSTS. Shared guidelines for PBT indications-based on the patient's age, estimated outcome, and tumor location-and centralization in high-level referral centers are needed to optimize the use of resources, since access to PBT remains a challenge due to the limited number of available proton therapy facilities.

Surgery and proton radiation therapy for pediatric base of skull chordomas: Long-term clinical outcomes for 204 patients

BACKGROUND

Data on clinical outcomes for base of skull (BOS) chordomas in the pediatric population is limited. We report patient outcomes after surgery and proton radiotherapy (PRT).

METHODS

Pediatric patients with BOS chordomas were treated with PRT or combined proton/photon approach (proton-based; for most, 80% proton/20% photon) at the Massachusetts General Hospital from 1981 to 2021. Endpoints of interest were overall survival (OS), disease-specific survival, progression-free survival (PFS), freedom from local recurrence (LC), and freedom from distant failure (DC).

RESULTS

Of 204 patients, median age at diagnosis was 11.1 years (range, 1-21). Chordoma location included 59% upper and/or middle clivus, 36% lower clivus, 4% craniocervical junction, and 1% nasal cavity. Fifteen (7%) received pre-RT chemotherapy. Forty-seven (23%) received PRT, and 157 (77%) received comboRT. Median total dose was 76.7 Gy (RBE) (range, 59.3-83.3). At a median follow-up of 10 years (interquartile range, 5-16 years), 56 recurred. Median OS and PFS were 26 and 25 years, with 5-, 10-, and 20-year OS and PFS rates of 84% and 74%, 78% and 69%, and 64% and 64%, respectively. Multivariable actuarial analyses showed poorly differentiated subtype, radiographical progression prior to RT, larger treatment volume, and lower clivus location to be prognostic factors for worse OS, PFS, and LC. RT was well tolerated at a median follow-up of 9 years (interquartile range, 4-16 years). Side effects included 166 patients (80%) with mild/moderate acute toxicities, 24 (12%) patients with late toxicities, and 4 (2%) who developed secondary radiation-related malignancies.

CONCLUSION

This is the largest cohort of BOS chordomas in the literature, pediatric and/or adult. High-dose PRT following surgical resection is effective with low rates of late toxicity.

Proton therapy in the most common pediatric non-central nervous system malignancies: an overview of clinical and dosimetric outcomes

Radiation therapy represents an important approach in the therapeutic management of children and adolescents with malignant tumors and its application with modern techniques – including Proton Beam Therapy (PBT) – is of great interest. In particular, potential radiation-induced injuries and secondary malignancies – also associated to the prolonged life expectancy of patients – are still questions of concern that increase the debate on the usefulness of PBT in pediatric treatments. This paper presents a literary review of current applications of PBT in non-Central Nervous System pediatric tumors (such as retinoblastoma, Hodgkin Lymphoma, Wilms tumor, bone and soft tissues sarcomas). We specifically reported clinical results achieved with PBT and dosimetric comparisons between PBT and the most common photon-therapy techniques. The analysis emphasizes that PBT minimizes radiation doses to healthy growing organs, suggesting for reduced risks of late side-effects and radiation-induced secondary malignancies. Extended follow up and confirms by prospective clinical trials should support the effectiveness and long-term tolerance of PBT in the considered setting.

125 I interstitial brachytherapy in management of pediatric skull base tumors

BACKGROUND

The purpose of this study was to present our preliminary assessment of the safety and efficacy of ¹²⁵ I interstitial brachytherapy (IBT) in the management of pediatric skull base tumors.

METHODS

Thirty pediatric patients with skull base tumors treated with ¹²⁵ I IBT from April 2007 to May 2017 were included in this study. The probabilities of local control (LC) and overall survival (OS) were calculated by the Kaplan-Meier method.

RESULTS

The one- and two-year LC rates were 96.7% and 74.8%, respectively. The one- and two-year OS rates were 93.3% and 72.2%, respectively. No severe acute toxicity was observed. Severe late toxicities were observed in one (3.33%) of 30 patients.

CONCLUSION

¹²⁵ I IBT is effective and safe in the management of pediatric skull base tumors, with satisfactory cosmetic and functional outcomes.

Relating Linear Energy Transfer to the Formation and Resolution of DNA Repair Foci After Irradiation with Equal Doses of X-ray Photons, Plateau, or Bragg-Peak Protons

Proton beam therapy is increasingly applied for the treatment of human cancer, as it promises to reduce normal tissue damage. However, little is known about the relationship between linear energy transfer (LET), the type of DNA damage, and cellular repair mechanisms, particularly for cells irradiated with protons. We irradiated cultured cells delivering equal doses of X-ray photons, Bragg-peak protons, or plateau protons and used this set-up to quantitate initial DNA damage (mainly DNA double strand breaks (DSBs)), and to analyze kinetics of repair by detecting γH2A.X or 53BP1 using immunofluorescence. The results obtained validate the reliability of our set-up in delivering equal radiation doses under all conditions employed. Although the initial numbers of γH2A.X and 53BP1 foci scored were similar under the different irradiation conditions, it was notable that the maximum foci level was reached at 60 min after irradiation with Bragg-peak protons, as compared to 30 min for plateau protons and photons. Interestingly, Bragg-peak protons induced larger and irregularly shaped γH2A.X and 53BP1 foci. Additionally, the resolution of these foci was delayed. These results suggest that Bragg-peak protons induce DNA damage of increased complexity which is difficult to process by the cellular repair apparatus.

Proton therapy for pediatric malignancies: Fact, figures and costs. A joint consensus statement from the pediatric subcommittee of PTCOG, PROS and EPTN

Radiotherapy plays an important role in the management of childhood cancer, with the primary aim of achieving the highest likelihood of cure with the lowest risk of radiation-induced morbidity. Proton therapy (PT) provides an undisputable advantage by reducing the radiation 'bath' dose delivered to non-target structures/volume while optimally covering the tumor with tumoricidal dose. This treatment modality comes, however, with an additional costs compared to conventional radiotherapy that could put substantial financial pressure to the health care systems with societal implications. In this review we assess the data available to the oncology community of PT delivered to children with cancer, discuss on the urgency to develop high-quality data. Additionally, we look at the advantage of combining systemic agents with protons and look at the cost-effectiveness data published so far.

Proton therapy for pediatric head and neck malignancies

PURPOSE

Pediatric head and neck malignancies are managed with intensive multimodality therapy. Proton beam therapy (PBT) may reduce toxicity by limiting exposure of normal tissue to radiation. In this study, we report acute toxicities and early outcomes following PBT for pediatric head and neck malignancies.

MATERIALS AND METHODS

Between 2010 and 2016, pediatric patients with nonhematologic malignancies of the head and neck were treated with PBT. Clinical and dosimetric data were abstracted from the medical record and treatment planning system with institutional review board approval.

RESULTS

Sixty-nine consecutive pediatric patients were treated with proton-based radiotherapy for head and neck malignancies. Thirty-five were treated for rhabdomyosarcoma to a median dose of 50.4 Gy relative biological effectiveness [RBE]. Ten patients were treated for Ewing sarcoma to a median dose of 55.8 Gy[RBE]. Twenty-four patients were treated for other histologies to a median dose of 63.0 Gy[RBE]. Grade 3 oral mucositis, anorexia, and dysphagia were reported to be 4, 22, and 7%, respectively. Actuarial 1-year freedom from local recurrence was 92% (95% CI 80-97). Actuarial 1-year overall survival was 93% (95% CI 79-98) in the entire cohort. Oral cavity mucositis was significantly correlated with oral cavity dose (D80 and D50 [P < 0.05], where D80 and D50 are dose to 50% of the volume and dose to 80% of the volume, respectively).

CONCLUSIONS

In this study, we report low rates of acute toxicity in a cohort of pediatric patients with head and neck malignancies. PBT appears safe for this patient population, with local control rates similar to historical reports. Longer follow-up will be required to evaluate late toxicity and long-term disease control.

Metastatic clival chordoma: a case report of multiple extraneural metastases following resection and proton beam radiotherapy in a 5-year old boy

The authors report the case of a 5-year-old boy in whom extraneural metastases developed 5 years after he underwent an occipitocervical fusion and transoral approach to treat a clival chordoma without local recurrence. Following primary resection, the patient's postoperative course was complicated by recurrent meningitis secondary to CSF leak, which responded to antibiotics, and communicating hydrocephalus, for which a ventriculoperitoneal shunt was placed. The patient then underwent postoperative proton beam radiotherapy. Five years following his initial presentation, surveillance imaging revealed a new asymptomatic lung mass for which the patient underwent thoracotomy and resection of the mass. Histological examination of the lung mass revealed findings consistent with a de-differentiated chordoma, confirming extraneural metastasis from the original tumor without evidence of local recurrence. Chest wall and scalp metastases subsequently developed, and the patient was started on an adjuvant chemotherapy regimen that included imatinib and rapamycin followed by subsequent nivolumab and an EZH2 inhibitor for recurrent, disseminated disease. Despite this patient's remote and distant metastases, primary gross-total resection for chordoma remains a critical treatment objective, followed by proton beam radiotherapy. This case illustrates the importance of interval posttreatment imaging and the emerging potential to treat chordoma with molecularly targeted therapies.

Reprint of "Chordoma in children: Case-report and review of literature"

We report an exceptional case of a very late local failure in a 9-year-old boy presenting with a chordoma of the cranio-cervical junction. The child was initially treated with a combination of surgical resection followed by high dose photon-proton radiation therapy. This aggressive therapy allowed a 9-year remission with minimal side-effects. Unfortunately, he subsequently presented with a local failure managed with a second full-dose course of protons. The child died one year later from local bleeding of unclear etiology.

Clinical Applications of Proton Radiation Treatment at Loma Linda University: Review of a Fifteen-year Experience

Proton radiation therapy has been used at Loma Linda University Medical Center for 15 years, sometimes in combination with photon irradiation, surgery, and chemotherapy, but often as the sole modality. Our initial experience was based on established studies showing the utility of protons for certain management problems, but since then we have engaged in a planned program to exploit the capabilities of proton radiation and expand its applications in accordance with progressively accumulating clinical data. Our cumulative experience has confirmed that protons are a superb tool for delivering conformal radiation treatments, enabling delivery of effective doses of radiation and sparing normal tissues from radiation exposure.

Proton beam therapy in the management of skull base chordomas: systematic review of indications, outcomes, and implications for neurosurgeons

BACKGROUND

Chordomas are rare tumours affecting the skull base. There is currently no clear consensus on the post-surgical radiation treatments that should be used after maximal tumour resection. However, high-dose proton beam therapy is an accepted option for post-operative radiotherapy to maximise local control, and in the UK, National Health Service approval for funding abroad is granted for specific patient criteria.

OBJECTIVES

To review the indications and efficacy of proton beam therapy in the management of skull base chordomas. The primary outcome measure for review was the efficacy of proton beam therapy in the prevention of local occurrence.

METHODS

A systematic review of English and non-English articles using MEDLINE (1946-present) and EMBASE (1974-present) databases was performed. Additional studies were reviewed when referenced in other studies and not available on these databases. Search terms included chordoma or chordomas. The PRISMA guidelines were followed for reporting our findings as a systematic review.

RESULTS

A total of 76 articles met the inclusion and exclusion criteria for this review. Limitations included the lack of documentation of the extent of primary surgery, tumour size, and lack of standardised outcome measures. Level IIb/III evidence suggests proton beam therapy given post operatively for skull base chordomas results in better survival with less damage to surrounding tissue.

CONCLUSIONS

Proton beam therapy is a grade B/C recommended treatment modality for post-operative radiation therapy to skull base chordomas. In comparison to other treatment modalities long-term local control and survival is probably improved with proton beam therapy. Further, studies are required to directly compare proton beam therapy to other treatment modalities in selected patients.

Chordoma in children: Case-report and review of literature

We report an exceptional case of a very late local failure in a 9-year-old boy presenting with a chordoma of the cranio-cervical junction. The child was initially treated with a combination of surgical resection followed by high dose photon-proton radiation therapy. This aggressive therapy allowed a 9-year remission with minimal side-effects. Unfortunately, he subsequently presented with a local failure managed with a second full-dose course of protons. The child died one year later from local bleeding of unclear etiology.

Paediatric Chordomas

Paediatric chordomas are rare malignant tumours arising from primitive notochordal remnants with a high rate of recurrence. Only 5 % of them occur in the first two decades such less than 300 paediatric cases have been reported so far in the literature. In children, the average age at diagnosis is 10 years with a male-to-female ratio closed to 1. On the opposite to adults, the majority of paediatric chordomas are intracranial, characteristically centered on the sphenooccipital synchondrosis. Metastatic spread seems to be the prerogative of the under 5-year-old children with more frequent sacro-coccygeal locations and undifferentiated histology. The clinical presentation depends entirely on the tumour location. The most common presenting symptoms are diplopia and signs of raised intracranial pressure. Sacrococcygeal forms may present with an ulcerated subcutaneous mass, radicular pain, bladder and bowel dysfunctions. Diagnosis is suspected on computerised tomography showing the bone destruction and with typically lobulated appearance, hyperintense on T2-weighted magnetic resonance imaging. Today, treatment relies on as complete surgical resection as possible (rarely achieved because of frequent invasiveness of functional structures) followed by adjuvant radiotherapy by proton therapy. The role of chemotherapy has not been proven. Prognosis is better than in adults and depends on the extent of surgical resection, age and histology subgroup. Biological markers are still lacking to improve prognosis by developing targeted therapy.

Enigmatic entity in childhood: clival chordoma from a tertiary center's perspective

PURPOSE

Chordoma is a rare neoplasm that arises from embryonic notochordal remnants along the axial skeleton (i.e., clivus, sacrum) and the vertebral bodies. They comprise less than 1 % of CNS tumors and 1-4 % of all bone malignancies. It rarely affects children and adolescents (<5 %). Chordomas are locally aggressive and highly recurrent. Their management is challenging for clinicians.

METHODS

This retrospective study includes six pediatric patients with pathological evidence of clival chordoma. These cases were identified over a period of 15 years in a tertiary care institute.

RESULTS

There were two boy and four girls with a mean age of 10.6 years (range, 4-16 years). The chief complaint was due to cranial nerve palsy (or dysfunction), mostly affecting lower cranial nerves (66.6 %), followed by diplopia and headache. One patient had obstructive sleep apnea. All patients were operated and a total of 15 surgeries were performed (mean, 2.5). Tumor recurrence was observed in four patients (67 %). Two-year and 5-year progression-free survivals (PFS) were 67 and 33 %, respectively. None of the patients were lost either during the surgery or the follow-up period (6.9 years: 1-14 years).

CONCLUSIONS

Clival chordomas are challenging tumors in neurosurgical practice. A multidisciplinary approach is warranted in each patient. Today, the best management strategy seems to be surgical resection followed by radiotherapy. Chemotherapy should be considered in selective and preference basis. Sharing institutional experiences will provide future insights in prognosis of these rare tumors. Implementing newer surgical instruments, endoscope in particular, is encouraged in management of the clival chordomas.

Skull base chondrosarcoma radiosurgery: report of the North American Gamma Knife Consortium

OBJECT

Stereotactic radiosurgery (SRS) is a potentially important option for patients with skull base chondrosarcomas. The object of this study was to analyze the outcomes of SRS for chondrosarcoma patients who underwent this treatment as a part of multimodality management.

METHODS

Seven participating centers of the North American Gamma Knife Consortium (NAGKC) identified 46 patients who underwent SRS for skull base chondrosarcomas. Thirty-six patients had previously undergone tumor resections and 5 had been treated with fractionated radiation therapy (RT). The median tumor volume was 8.0 cm3 (range 0.9-28.2 cm3), and the median margin dose was 15 Gy (range 10.5-20 Gy). Kaplan-Meier analysis was used to calculate progression-free and overall survival rates.

RESULTS

At a median follow-up of 75 months after SRS, 8 patients were dead. The actuarial overall survival after SRS was 89% at 3 years, 86% at 5 years, and 76% at 10 years. Local tumor progression occurred in 10 patients. The rate of progression-free survival (PFS) after SRS was 88% at 3 years, 85% at 5 years, and 70% at 10 years. Prior RT was significantly associated with shorter PFS. Eight patients required salvage resection, and 3 patients (7%) developed adverse radiation effects. Cranial nerve deficits improved in 22 (56%) of the 39 patients who deficits before SRS. Clinical improvement after SRS was noted in patients with abducens nerve paralysis (61%), oculomotor nerve paralysis (50%), lower cranial nerve dysfunction (50%), optic neuropathy (43%), facial neuropathy (38%), trochlear nerve paralysis (33%), trigeminal neuropathy (12%), and hearing loss (10%).

CONCLUSIONS

Stereotactic radiosurgery for skull base chondrosarcomas is an important adjuvant option for the treatment of these rare tumors, as part of a team approach that includes initial surgical removal of symptomatic larger tumors.

Spot scanning proton therapy for malignancies of the base of skull: treatment planning, acute toxicities, and preliminary clinical outcomes

PURPOSE

To describe treatment planning techniques and early clinical outcomes in patients treated with spot scanning proton therapy for chordoma or chondrosarcoma of the skull base.

METHODS AND MATERIALS

From June 2010 through August 2011, 15 patients were treated with spot scanning proton therapy for chordoma (n=10) or chondrosarcoma (n=5) at a single institution. Toxicity was prospectively evaluated and scored weekly and at all follow-up visits according to Common Terminology Criteria for Adverse Events, version 3.0. Treatment planning techniques and dosimetric data were recorded and compared with those of passive scattering plans created with clinically applicable dose constraints.

RESULTS

Ten patients were treated with single-field-optimized scanning beam plans and 5 with multifield-optimized intensity modulated proton therapy. All but 2 patients received a simultaneous integrated boost as well. The mean prescribed radiation doses were 69.8 Gy (relative biological effectiveness [RBE]; range, 68-70 Gy [RBE]) for chordoma and 68.4 Gy (RBE) (range, 66-70) for chondrosarcoma. In comparison with passive scattering plans, spot scanning plans demonstrated improved high-dose conformality and sparing of temporal lobes and brainstem. Clinically, the most common acute toxicities included fatigue (grade 2 for 2 patients, grade 1 for 8 patients) and nausea (grade 2 for 2 patients, grade 1 for 6 patients). No toxicities of grades 3 to 5 were recorded. At a median follow-up time of 27 months (range, 13-42 months), 1 patient had experienced local recurrence and a second developed distant metastatic disease. Two patients had magnetic resonance imaging-documented temporal lobe changes, and a third patient developed facial numbness. No other subacute or late effects were recorded.

CONCLUSIONS

In comparison to passive scattering, treatment plans for spot scanning proton therapy displayed improved high-dose conformality. Clinically, the treatment was well tolerated, and with short-term follow-up, disease control rates and toxicity profiles were favorable.

Treatment and Outcome of Patients with Skull Base Chordoma: A Meta-analysis

Objective Chordoma is a locally aggressive tumor. The aim of this study was to assess the efficacy of different surgical approaches and adjuvant radiation modalities used to treat these patients. Design Meta-analysis. Main Outcome Measures Overall survival (OS), disease-specific survival (DSS), and progression-free survival (PFS). Results The 5-year OS and PFS rates of the whole cohort (n = 467) were 86% and 65.7%, respectively. The 5-year DSS for patients who underwent open surgery and endoscopic surgery was 45% and 49%, respectively (p = 0.8); PFS was 94% and 79%, respectively (p = 0.11). The 5-year OS of patients treated with surgery followed by adjuvant radiotherapy was 90% compared with 70% of those treated by surgery alone (p = 0.24). Patients undergoing partial resection without adjuvant radiotherapy had a 5-year OS of 41% and a DSS of 45%, significantly lower than in the total-resection group (p = 0.0002 and p = 0.01, respectively). The complication rates were similar in the open and endoscopic groups. Conclusions Patients undergoing total resection have the best outcome; adjuvant radiation therapy improves the survival of patients undergoing partial resection. In view of the advantages of minimally invasive techniques, endoscopic surgery appears an appropriate surgical approach for this disease.

Proton radiotherapy for pediatric sarcoma

Pediatric sarcomas represent a distinct group of pathologies, with approximately 900 new cases per year in the United States alone. Radiotherapy plays an integral role in the local control of these tumors, which often arise adjacent to critical structures and growing organs. The physical properties of proton beam radiotherapy provide a distinct advantage over standard photon radiation by eliminating excess dose deposited beyond the target volume, thereby reducing both the dose of radiation delivered to non-target structures as well as the total radiation dose delivered to a patient. Dosimetric studies comparing proton plans to IMRT and 3D conformal radiation have demonstrated the superiority of protons in numerous pediatric malignancies and data on long-term clinical outcomes and toxicity is emerging. In this article, we review the existing clinical and dosimetric data regarding the use of proton beam radiation in malignant bone and soft tissue sarcomas.

New strategies in radiation therapy: exploiting the full potential of protons

Protons provide significant dosimetric advantages compared with photons because of their unique depth-dose distribution characteristics. However, they are more sensitive to the effects of intra- and intertreatment fraction anatomic variations and uncertainties in treatment setup. Furthermore, in the current practice of proton therapy, the biologic effectiveness of protons relative to photons is assumed to have a generic fixed value of 1.1. However, this is a simplification, and it is likely higher in different portions of the proton beam. Current clinical practice and trials have not fully exploited the unique physical and biologic properties of protons. Intensity-modulated proton therapy, with its ability to manipulate energies (in addition to intensities), provides an entirely new dimension, which, with ongoing research, has considerable potential to increase the therapeutic ratio.

Initial clinical experience with scanned proton beams at the Italian National Center for Hadrontherapy (CNAO)

We report the initial toxicity data with scanned proton beams at the Italian National Center for Hadrontherapy (CNAO). In September 2011, CNAO commenced patient treatment with scanned proton beams within two prospective Phase II protocols approved by the Italian Health Ministry. Patients with chondrosarcoma or chordoma of the skull base or spine were eligible. By October 2012, 21 patients had completed treatment. Immobilization was performed using rigid non-perforated thermoplastic-masks and customized headrests or body-pillows as indicated. Non-contrast CT scans with immobilization devices in place and MRI scans in supine position were performed for treatment-planning. For chordoma, the prescribed doses were 74 cobalt grey equivalent (CGE) and 54 CGE to planning target volume 1 (PTV1) and PTV2, respectively. For chondrosarcoma, the prescribed doses were 70 CGE and 54 CGE to PTV1 and PTV2, respectively. Treatment was delivered five days a week in 35-37 fractions. Prior to treatment, the patients' positions were verified using an optical tracking system and orthogonal X-ray images. Proton beams were delivered using fixed-horizontal portals on a robotic couch. Weekly MRI incorporating diffusion-weighted-imaging was performed during the course of proton therapy. Patients were reviewed once weekly and acute toxicities were graded with the Common Terminology Criteria for Adverse Events (CTCAE). Median age of patients = 50 years (range, 21-74). All 21 patients completed the proton therapy without major toxicities and without treatment interruption. Median dose delivered was 74 CGE (range, 70-74). The maximum toxicity recorded was CTCAE Grade 2 in four patients. Our preliminary data demonstrates the clinical feasibility of scanned proton beams in Italy.

Basic principles of paediatric radiotherapy

This article gives an introduction to the fundamentals of paediatric radiotherapy, describing the historical development of the speciality and its organisation in the UK, the clinical pathway (including issues around immobilisation) and an overview of indications for radiotherapy in the paediatric population. Late effects of radiotherapy, their mitigation and the role of the late effects clinic are summarised.

Skull base reconstruction in the pediatric patient

Tumors of the skull base are rare in children and adolescents and present a complicated management problem for oncologists and surgeons alike. Surgical resection is an integral component of the management of many pediatric neoplasms, especially those that are benign or, though not frankly malignant, are locally invasive. The general principles of skull base reconstruction following tumor ablation are applicable to nearly all patients; the reconstructive algorithm, however, is particularly complex in the pediatric population and the potential benefits of therapy must be balanced against the cumulative impact on craniofacial growth and maturity and the donor site morbidity. A retrospective analysis of all patients less than 19 years of age who underwent resection of a skull base tumor was performed. Particular emphasis was placed on the 12 patients who required complex reconstruction by the plastic surgical service. This represents approximately a third of the operated patients. Data were recorded on patient age, tumor pathology and location, prior therapies, surgical approach, extent of resection, margin status, defect components, details of reconstructive methods employed, complications, additional procedures or interventions, and the use and timing of adjuvant therapies. Patient outcome at most recent follow-up was recorded. All patients were followed clinically and by MRI and/or CT scan of the skull base. The reconstructive details recorded included flap choice, recipient vessels, and any concomitant procedures performed. The indications for and details of any staged surgical revisions or prosthetics were also noted. Complications recorded included partial or total flap loss, cerebrospinal fluid leakage, meningitis, infection, abscess, hematoma or seroma formation, delayed healing, and donor site dysfunction. The vertical rectus abdominis myocutaneous free flap was the most common means of reconstruction utilized in this series. Three of 12 patients had reconstruction related complications. Delayed reconstructive procedures or prosthetic interventions have been performed in 6 of the 12 patients who underwent complex reconstructions. On the basis of our experience and previous reports in the literature, we offer the following guidelines for the successful multidisciplinary care of children and adolescents undergoing skull base reconstruction after tumor resection: (1) skull base reconstruction may be safely performed in children and adolescents using free tissue transfer or local flaps; (2) larger defects and those involving more than one anatomic region of the skull base should be repaired with soft-tissue free flaps; and (3) because of the versatility and reliability of free flaps, pedicled flaps should be reserved for limited defects. Because of the potentially synergistic effects of multimodality treatment for skull base malignancies on craniofacial growth and development, we advocate soft-tissue reconstruction as the primary technique, reserving bony flaps for definitive procedures in survivors who have reached skeletal maturity.

Temporal Chondroblastoma with a Novel Chromosomal Translocation (2;5) (q33;q13)

The case of a 51-year-old man with a large temporal mass is presented. The mass eroded the floor of the middle fossa medially to the sphenoid sinus. A combined approach with neurosurgery and otolaryngology was performed to achieve maximal resection of the mass. Pathology was typical for chondroblastoma: a rare, benign but locally invasive chondroid tumor. Genetic testing revealed a translocation of (2;5) (q33;q13). This is a unique genetic mutation in all chondroid tumors to our knowledge. The diagnostic utility or role of this mutation in the pathobiology of this tumor remains to be determined.

Stereotactic Radiosurgery for Chordoma

BACKGROUND:

Although considered slow-growing, low-grade malignancies, chordomas are locally aggressive and destructive tumors with high recurrence rates.

OBJECTIVE:

To assess patient survival, tumor control, complications, and selected variables that predict outcome in patients who underwent Gamma Knife stereotactic radiosurgery (SRS) as primary, adjuvant, or salvage management for chordomas of the skull base.

METHODS:

Six participating centers of the North American Gamma Knife Consortium identified 71 patients who underwent SRS for chordoma. The median patient age was 45 years (range, 7-80 years). The median SRS target volume was 7.1 cm3 (range, 0.9-109 cm3), and median margin dose was 15.0 Gy (range, 9-25 Gy).

RESULTS:

At a median follow-up of 5 years (range, 0.6-14 years) after SRS, 23 patients died of tumor progression. The 5-year actuarial overall survival after SRS was 80% for the entire group, 93% for the no prior fractionated radiation therapy (RT) group (n = 50), and 43% for the prior RT group (n = 21). Younger age, longer interval between initial diagnosis and SRS, no prior RT, &lt; 2 cranial nerve deficits, and smaller total tumor volume were significantly associated with longer patient survival. The 5-year treated tumor control rate after SRS was 66% for the entire group, 69% for the no prior RT group, and 62% for the prior RT group. Older age, recurrent group, prior RT, and larger tumor volume were significantly associated with worse tumor control.

CONCLUSION:

Stereotactic radiosurgery is a potent treatment option for small sized chordomas, especially in younger patients and as part of a multipronged attack that includes surgical resection when possible.

The role of chemotherapy in pediatric clival chordomas

The purpose of this retrospective study was to review the role of chemotherapy in the treatment, management and outcome of children diagnosed with clival chordomas. The medical records of six pediatric chordoma patients diagnosed at Childrens Hospital Los Angeles between 1995 and 2005 were reviewed. Of the six patients reviewed, all underwent an initial surgical resection. Following resection, three received a combination of chemotherapy and radiation therapy, two received chemotherapy alone and one patient refused both forms of therapy; this patient expired of progressive tumor. One patient developed acute monoblastic leukemia (M5a subtype) and died of intracranial hemorrhage during induction chemotherapy, 39 months after initial diagnosis. MRI of brain and spine showed disease progression shortly before his death. Two patients who received chemotherapy only after surgery, one patient who received chemotherapy at relapse following irradiation and one patient who received irradiation followed by chemotherapy are alive with stable radiographic abnormalities at a median follow-up of 9 years from diagnosis (range: 6-13 years). Chemotherapeutic agents included ifosfamide and etoposide in all four surviving patients. Chemotherapy with ifosfamide and etoposide may have a role in the treatment of pediatric clival chordomas when used alone or in combination with irradiation.

Proton beam therapy in pediatric oncology

Pediatric caregivers and parents are eager to know the role of proton beam therapy (PBT) in the treatment of children with brain and solid tumors and other diseases for which radiation therapy is indicated. Although the number of children treated with PBT for the most common pediatric tumors is relatively small and outcome data are clearly lacking, modeling radiation dose, volume, and outcomes based on photon benchmark data and clinical experience suggest an advantage for PBT and an opportunity to reduce or eliminate many of the early and late effects of radiation therapy. As the number of centers available to treat children increases, it is incumbent on those with access to this modality to optimize other critical aspects of radiotherapy and cancer care and follow-up that are requisite to achieving disease control and high-quality survivorship. Even though the focus of pediatric radiation oncology is weighted toward side effect reduction, there is an opportunity for dose escalation or biologically optimized radiotherapy in a number of diseases or settings in which high-dose irradiation is considered unapproachable. Justification for PBT in pediatric patients should be realized once the costs of treating acute symptoms, growth hormone deficiency, orthopedic deformities, and secondary malignancies are studied and reduced.

Current clinical evidence for proton therapy

Proton beam therapy provides the opportunity for more localized delivery of ionizing radiation with the potential for improved normal tissue avoidance to reduce treatment related morbidity and to allow for dose escalation to improve disease control and survival without increased toxicity. However, a systematic review of published peer-reviewed literature reported previously and updated here is devoid of any clinical data demonstrating benefit in terms of survival, tumor control, or toxicity in comparison with best conventional treatment for any of the tumors so far treated including skull base and ocular tumors, prostate cancer and childhood malignancies. The current lack of evidence for benefit of protons should provide a stimulus for continued research. Well designed in silico clinical trials using validated normal tissue complication probability-models are important to predict the magnitude of benefit for individual tumor sites but the future use of protons should be guided by clear evidence of benefit demonstrated in well-designed prospective studies, away from commercial influence, and this is likely to require international collaboration. Any complex and expensive technology, including proton therapy, should not be employed on the basis of belief alone and requires testing to avoid inappropriate use of potential detriment to future patients.

[Is proton beam therapy the future of radiotherapy? Part I: clinical aspects]

Proton beam therapy uses positively charged particles, protons, whose physical properties improve dose-distribution (Bragg peak characterized by a sharp distal and lateral penumbra) compared with conventional photon-based radiation therapy (X-ray). These ballistic advantages apply to the treatment of deep-sited tumours located close to critical structures and requiring high-dose levels. [60-250 MeV] proton-beam therapy is now widely accepted as the "gold standard" in specific indications in adults--ocular melanoma, chordoma and chondrosarcoma of the base of skull --and is regarded as a highly promising treatment modality in the treatment of paediatric malignancies (brain tumours, sarcomas…). This includes the relative sparing of surrounding normal organs from low and mid-doses that can cause deleterious side-effects such as radiation-induced secondary malignancies. Other clinical studies are currently testing proton beam in dose-escalation evaluations, in prostate, lung, hepatocellular cancers, etc. Clinical validation of these new indications appears necessary. To date, over 60,000 patients worldwide have received part or all of their radiation therapy program by proton beams, in approximately 30 treatment facilities.

The potential of proton beam radiation therapy in intracranial and ocular tumours

A group of oncologists and hospital physicists have estimated the number of patients in Sweden suitable for proton beam therapy. The estimations have been based on current statistics of tumour incidence, number of patients potentially eligible for radiation treatment, scientific support from clinical trials and model dose planning studies and knowledge of the dose-response relations of different tumours and normal tissues. In intracranial benign and malignant tumours, it is estimated that between 130 and 180 patients each year are candidates for proton beam therapy. Of these, between 50 and 75 patients have malignant glioma, 30-40 meningeoma, 20-25 arteriovenous malformations, 20-25 skull base tumours and 10-15 pituitary adenoma. In addition, 15 patients with ocular melanoma are candidates.

The potential of proton beam therapy in paediatric cancer

A group of Swedish oncologists and hospital physicists have estimated the number of patients in Sweden suitable for proton beam therapy. The estimations have been based on current statistics of tumour incidence, number of patients potentially eligible for radiation treatment, scientific support from clinical trials and model dose planning studies and knowledge of the dose-response relations of different tumours and normal tissues. It is estimated that in paediatric cancers, proton beams are of potential importance in 80-100 children annually in Sweden. About 20 of the patients have medulloblastoma. The main purpose is to reduce late sequelae, but these are also increased chances to avoid myelosupression during e.g. concomitant chemo-radiation and to further intensify the chemotherapy.

Radiation techniques in neuro-oncology

Radiation therapy plays a critical role in the management of tumors of the brain. A variety of radiotherapy techniques have been used to treat these tumors. This review describes both classic and more recent and advanced techniques available to manage these tumors. Included is a discussion of standard two- and three-dimensional radiation, as well as intensity-modulated radiotherapy, image-guided radiation therapy, stereotactic radiosurgery, and heavy particles.

Carbon ion radiotherapy for pediatric patients and young adults treated for tumors of the skull base

BACKGROUND

The current study was conducted to evaluate the outcome of carbon ion radiotherapy (RT) in children and young adults with skull base chordomas and chondrosarcomas.

METHODS

Between 1997 and 2007, 394 patients were treated with carbon ion RT at Gesellschaft für Schwerionenforschung in Darmstadt, Germany. Of these patients, 17 patients were aged<or=21 years. Seventeen of these young patients were treated for chordoma or low-grade chondrosarcoma of the skull base and were analyzed in this study. Irradiation was performed after primary diagnosis in 14 patients (82%) and for recurrent tumors in 3 patients (18%). The authors applied a median total dose of 60 gray equivalents (Gy E) (range, 60-66.6 Gy E) in a fractionation of 7x3 Gy E per week of carbon ion RT using the raster scan technique. All patients were observed prospectively on a regular basis after carbon ion RT.

RESULTS

The median follow-up time was 49 months. Treatment was well tolerated without severe side effects and could be completed on an outpatient basis in all patients without interruptions. One patient with chordoma developed tumor progression at 60 months after carbon ion RT. All other patients demonstrated no signs of tumor progression during follow-up.

CONCLUSIONS

Despite its promising outcome in children and young adults with chordomas and chondrosarcomas, further evaluation in a larger patient collective is required. Randomized studies comparing the outcome after carbon ion RT with proton RT are especially needed to evaluate the role of particle beams in the treatment of skull base tumors in children and young adults.

Proton therapy in chordoma of the base of the skull: a systematic review

Chordoma is a rare, slow-growing, locally aggressive, primary bone tumor that arises from the skull base region in approximately 25-35% of cases. The therapeutic approach to chordoma has traditionally been surgery, followed by radiation therapy. The advent of charged particle radiotherapy has let us consider protons as the postoperative treatment of choice, but no controlled studies have yet confirmed the superiority of protons over photons. During January 2008, two independent researchers conducted a systematic review of the current data on the treatment of base of the skull chordoma C with proton therapy (PT) and, for comparison, with other irradiation techniques (conventional radiation therapy, ion therapy, fractionated stereotactic radiation therapy, and radiosurgery). Two hundred and ten reports in total were retrieved (81 concerning PT). According to the inclusion criteria, 47 articles were considered in the analysis. There were no prospective trials (randomized or nonrandomized) but just seven uncontrolled single-arm studies for PT, providing clinical outcomes for 416 patients in total; these reports were mainly related to advanced inoperable or incompletely resected tumors. The therapeutic approach to chordoma of the base of the skull has traditionally relied on surgical control. Radiation therapy has demonstrated to be a valuable modality for local control in the postoperative setting, particularly with the advent of charged particle radiotherapy. The use of protons has shown better results in comparison to the use of conventional photon irradiation, resulting in the best long-term (10 years) outcome for this tumor with relatively few significant complications considering the high doses delivered with this therapeutic modality.