Proton and carbon ion radiotherapy in skull base chordomas: a prospective study based on a dual particle and a patient-customized treatment strategy

Carbon Ion Radiotherapy in the Head and Neck Cancers Treatment and its Potential Role in Personalized Treatment Approach- A Review of the Current Knowledge

PURPOSE OF REVIEW

Head and neck cancer (HNC) is a complex, heterogeneous group of malignancies. In treatment a combined modality therapy with surgery, radiotherapy and chemotherapy is usually advised. The use of charged particles was a breakthrough in radiation oncology and allowed the initiation of cancer treatment with high-precision. The purpose of the work is to discuss the role of carbon ion radiotherapy in the treatment of head and neck cancers.

RECENT FINDINGS

Heavy ions such as carbon have more favorable physical and radiobiological properties than photons. The unique properties of carbon ions enable radiotherapy with dose escalation to tumors, while reducing both, radiation dose to adjacent normal tissues and radiation area. Considering its exceptional features, carbon ion radiotherapy offers promising results with acceptable toxicity regarding treatment of uncommon and rare malignancies, especially treated for a recurrent disease. HNC patients with adenoid cystic carcinoma and mucosal melanoma of the head and neck, which are considered to be radiation resistant, should benefit more from carbon ion radiotherapy than proton beam therapy or conventional photon radiotherapy. Also selected patients with other head and neck malignancies can benefit form carbon ion radiotherapy including advanced salivary gland cancer and nasopharyngeal cancer patients. Carbon ion radiotherapy offers better dose distributions, higher tumor doses, and an increased odds of local control and prolonged survival. Carbon ion radiotherapy represents a promising alternative to conventional photon RT or even proton beam therapy especially in treatment of radioresistant tumors situated close to critical organs.

Proton beam and carbon ion radiotherapy in skull base chordoma: a systematic review, meta-analysis and meta-regression with trial sequential analysis

Chordomas are rare, locally aggressive tumors that have a high rate of recurrence, especially at the skull base. This systematic review and meta-analysis aimed to analyze the efficacy and safety of proton beam therapy (PBT) and carbon ion radiotherapy (CIRT) for skull base chordoma. We conducted a systematic search of MEDLINE, EMBASE, CENTRAL, Web of Science, and Ovid up to November 26, 2023, following the PRISMA statement. Studies involving more than 10 patients with skull base chordoma treated with PBT or CIRT were included. The outcomes analyzed were local control, overall survival, progression-free survival, and toxicities. Meta-analysis was performed using the Mantel-Haenszel method and the inverse variance method. Fourteen studies met the inclusion criteria, encompassing 1,145 patients (671 treated with PBT and 474 with CIRT). No significant difference was found between PBT and CIRT for 5-year local control (LC) and overall survival (OS). The only timepoint with a difference in local control was at 3 years, when PBT showed an advantage in local control (90% vs. 83% for CIRT; p = 0.05) and progression-free survival was similar (94% for PBT vs. 83% for CIRT; p = 0.09). Sensitivity analysis and meta-regression revealed no significant influence of predefined parameters on outcomes. Publication bias was suggested by asymmetrical funnel plots. Both PBT and CIRT are effective treatments for skull base chordoma, with comparable long-term efficacy. This meta-analysis underscores the need for individualized treatment approaches and further research to refine these therapies in clinical practice.

Inhomogeneity detection within a head-sized phantom using tracking of charged nuclear fragments in ion beam therapy

Objective.The highly conformal carbon-ion radiotherapy is associated with an increased sensitivity of the dose distributions to internal changes in the patient during the treatment course. Hence, monitoring methodologies capable of detecting such changes are of vital importance. We established experimental setup conditions to address the sensitivity of a monitoring approach based on secondary-fragment tracking for detecting clinically motivated air cavity dimensions in a homogeneous head-sized PMMA phantom in 40 mm depth.Approach.The air cavities were positioned within the entrance channel of a treatment field of 50 mm diameter at three lateral positions. The measured secondary-fragment emission profiles were compared to a reference measurement without cavities. The experiments were conducted at the Heidelberg Ion-Beam Therapy Center in Germany at typical doses and dose rates.Main results.Significances above a detectability threshold of 2σfor the larger cavities (20 mm diameter and 4 mm thickness, and 20 mm diameter and 2 mm thickness) across the entire treatment field. The smallest cavity of 10 mm diameter and 2 mm thickness, which is on the lower limit of clinical interest, could not be detected at any position. We also demonstrated that it is feasible to reconstruct the lateral position of the cavity on average within 2.8 mm, once the cavity is detected. This is sufficient for the clinicians to estimate medical effects of such a cavity and to decide about the need for a control imaging CT.Significance.This investigation defines well-controlled reference conditions for the evaluation of the performance of any kind of treatment monitoring method and its capability to detect internal changes within head-sized objects. Four air cavities with volumes between 0.31 cm3and 1.26 cm3were narrowed down around the detectability threshold of this secondary-fragment-based monitoring method.

Endoscopic Endonasal Approach for Clival Chordomas in Elderly Patients: Clinical Characteristics, Patient Outcome, and Recurrence Rate

Introduction  The endoscopic endonasal route has demonstrated to be the approach of choice for a large majority of clival chordomas (CCs). However, its results in elderly patients are under-evaluated in the literature. The aim of this study is to assess the surgical outcome for these patients, determining the factors associated with a larger tumor resection in this population. Materials and Methods  Our institutional database of CC has been retrospectively reviewed, to identify all cases over 65 years old, operated through an endoscopic endonasal approach (EEA). Preoperative clinical and radiological features were considered, as well as surgical results, morbidity, and patients' outcome at follow-up. Results  Out of our series of 143 endoscopic surgical procedures for CC, 34 (23.8%) were in patients older than 65 and 10 in older than 75 (7.0%). Gross tumor removal was achieved in 22 cases (64.7%). Complications consisted of 2 (5.9%) postoperative cerebrospinal leaks, 1 (2.9%) meningitis, 1 (2.9%) permanent cranial nerve VI palsy, 1 (2.9%) pneumonia, and 2 (5.9%) urinary infections. In 39.1% of cases, the preoperative ophthalmoplegia improved or resolved. Twenty-seven patients (79.4%) underwent radiation therapy. At follow-up (37.7 ± 44.9 months), 13 patients (38.2%) showed a recurrence/progression and 13 (38.3%) deceased. Conclusion  EEA can be a useful approach in elderlies, balancing the large tumor removal with an acceptable morbidity rate, even if higher than that for general CC population. However, patient selection remains crucial. A multidisciplinary evaluation is important to assess not only their medical conditions, but also their social and familiar conditions.

The Clinical Outcomes of Cervical Spine Chordoma: A Nationwide Multicenter Retrospective Study

OBJECTIVE

Chordoma, a rare malignant tumor originating from embryonal notochord remnants, exhibits high resistance to conventional treatments, making surgical resection imperative. However, the factors influencing prognosis specifically for cervical spine chordoma have not been clearly identified. We investigate the prognosis of cervical spine chordoma with factors influential in a nationwide multicenter retrospective study.

METHODS

This study included all patients diagnosed with cervical spine chordoma at 7 tertiary referral centers from January 1998 to March 2023, excluding those with clivus and thoracic spine chordomas extending into the cervical spine. Local recurrence (LR) was identified through follow-up magnetic resonance imaging, either as reappearance in completely resected tumors or regrowth in residual tumors. The study assessed LR and overall survival, analyzing factors influencing LR and death.

RESULTS

Forty-five patients with cervical spine chordoma had a mean age of 46.4 years. Over a median follow-up of 52 months, LR and distant metastasis were observed in 21 (46.7%) and 4 patients (8.9%), respectively, and 16 patients (36%) were confirmed dead. The 5-year and 10-year cumulative LR rates were 51.3% and 60%, respectively, while the 5-year and 10-year survival rates were 82% and 53%. Age was the only significant factor affecting mortality (hazard ratio, 1.04; 95% confidence interval, 1.04-1.07; p=0.015). Notably, the degree of resection and adjuvant therapy did not statistically significantly impact local tumor control and mortality.

CONCLUSION

This study, the largest multicenter retrospective analysis of cervical spine chordoma in Korea, identified age as the only factor significantly affecting patient survival.

A dosiomics approach to treatment outcome modeling in carbon ion radiotherapy for skull base chordomas

PURPOSE

To investigate the role of dosiomics features extracted from physical dose (DPHYS), RBE-weighted dose (DRBE) and dose-averaged Linear Energy Transfer (LETd), to predict the risk of local recurrence (LR) in skull base chordoma (SBC) treated with Carbon Ion Radiotherapy (CIRT). Thus, define and evaluate dosiomics-driven tumor control probability (TCP) models.

MATERIALS AND METHODS

54 SBC patients were retrospectively selected for this study. A regularized Cox proportional hazard model (r-Cox) and Survival Support Vector Machine (s-SVM) were tuned within a repeated Cross Validation (CV) and patients were stratified in low/high risk of LR. Models' performance was evaluated through Harrell's concordance statistic (C-index), and survival was represented through Kaplan-Meier (KM) curves. A multivariable logistic regression was fit to the selected feature sets to generate a dosiomics-driven TCP model for each map. These were compared to a reference model built with clinical parameters in terms of f-score and accuracy.

RESULTS

The LETd maps reached a test C-index of 0.750 and 0.786 with r-Cox and s-SVM, and significantly separated KM curves. DPHYS maps and clinical parameters showed promising CV outcomes with C-index above 0.8, despite a poorer performance on the test set and patients stratification. The LETd-based TCP showed a significatively higher f-score (0.67[0.52-0.70], median[IQR]) compared to the clinical model (0.4[0.32-0.63], p < 0.025), while DPHYS achieved a significatively higher accuracy (DPHYS: 0.73[0.65-0.79], Clinical: 0.6 [0.52-0.72]).

CONCLUSION

This analysis supports the role of LETd as relevant source of prognostic factors for LR in SBC treated with CIRT. This is reflected in the TCP modeling, where LETd and DPHYS showed an improved performance with respect to clinical models.

Systematic Review and Meta-Analysis of Particle Beam Therapy versus Photon Radiotherapy for Skull Base Chordoma: TRP-Chordoma 2024

[Objective] The aim of this study was to compare the efficacy of particle beam therapy (PT) with photon radiotherapy (RT) for treatment of skull base chordoma. [Methods] A systematic review was conducted for skull base chordoma treated with PT or photon RT reported from 1990 to 2022. Data were extracted for overall survival (OS) and progression-free survival (PFS), late adverse events, age, gender, gross total resection (GTR) rates, tumor volume, total irradiation dose, and treatment modality. Random-effects meta-regression analysis with the treatment modality as an explanatory variable was performed for each outcome to compare the modalities. [Results] A meta-analysis of 30 selected articles found 3- and 5-year OS rates for PT vs. photon RT or combined photon RT/proton beam therapy (PBT) of 90.8% (95% CI: 87.4-93.3%) vs. 89.5% (95% CI: 83.0-93.6%), p = 0.6543; 80.0% (95% CI: 75.7-83.6%) vs. 89.5% (95% CI: 83.0-93.6%), p = 0.6787. The 5-year PFS rates for PT vs. photon RT or photon RT/PBT were 67.8% (95% CI: 56.5-76.7%) vs. 40.2% (95% CI: 31.6-48.7%), p = 0.0004. A random-effects model revealed that the treatment modality (PT vs. photon RT or photon RT/PBT) was not a significant factor for 3-year OS (p = 0.42) and 5-year OS (p = 0.11), but was a significant factor for 5-year PFS (p < 0.0001). The rates of brain necrosis were 8-50% after PT and 0-4% after photon RT or photon RT/PBT. [Conclusion] This study shows that PT results in higher PFS compared to photon RT for skull base chordoma, but that there is a tendency for a higher incidence of brain necrosis with PT. Publication and analysis of further studies is needed to validate these findings.

Proton beam therapy for clival chordoma: Optimising rare cancer treatments in Australia

With the anticipated launch of the Australian Bragg Centre for Proton Therapy and Research (ABCPTR) in Adelaide, Australia, proton therapy will become a significant addition to existing cancer treatment options for Australians. The anticipated benefits will be particularly evident in rare cancers such as clival chordomas, a challenging tumour entity due to the anatomical relationship with critical structures, and proven radio-resistance to conventional radiation therapy. The article synthesises key findings from major studies and evaluates the current evidence supporting various management strategies for clival chordomas. It also considers the influence of institutional volume and multidisciplinary team management on patient outcomes and outlines how high-quality care can be effectively delivered within the Australian healthcare system, emphasising the potential impact of proton therapy on the treatment paradigm of clival chordomas in Australia.

How proton therapy fits into the management of adult intracranial tumors

Intracranial tumors include a challenging array of primary and secondary parenchymal and extra-axial tumors which cause neurologic morbidity consequential to location, disease extent, and proximity to critical neurologic structures. Radiotherapy can be used in the definitive, adjuvant, or salvage setting either with curative or palliative intent. Proton therapy (PT) is a promising advance due to dosimetric advantages compared to conventional photon radiotherapy with regards to normal tissue sparing, as well as distinct physical properties, which yield radiobiologic benefits. In this review, the principles of efficacy and safety of PT for a variety of intracranial tumors are discussed, drawing upon case series, retrospective and prospective cohort studies, and randomized clinical trials. This manuscript explores the potential advantages of PT, including reduced acute and late treatment-related side effects and improved quality of life. The objective is to provide a comprehensive review of the current evidence and clinical outcomes of PT. Given the lack of consensus and directives for its utilization in patients with intracranial tumors, we aim to provide a guide for its judicious use in clinical practice.

Patterns of Temporal Lobe Reaction and Radiation Necrosis after Particle Radiotherapy in Patients with Skull Base Chordoma and Chondrosarcoma-A Single-Center Experience

BACKGROUND

The current study aims to evaluate the occurrence of temporal lobe reactions and identify possible risk factors for patients who underwent particle therapy of the skull base.

METHODS

244 patients treated for skull base chordoma (n = 144) or chondrosarcoma (n = 100) at the Heidelberg Ion Beam Therapy Center (HIT) using a raster scan technique, were analyzed. Follow-up MRI-scans were matched with the initial planning images. Radiogenic reactions were contoured and analyzed based on volume and dose of treatment.

RESULTS

51 patients with chordoma (35.4%) and 30 patients (30%) with chondrosarcoma experienced at least one temporal lobe reaction within the follow-up period (median 49 months for chondrosarcoma, 62 months for chordoma). Age, irradiated volume, and dose values were significant risk factors for the development of temporal lobe reactions with the highest significance for the value of DMax-7 being defined as the dose maximum in the temporal lobe minus the 7cc with the highest dose (p = 0.000000000019; OR 1.087).

CONCLUSION

Temporal lobe reactions are a common side effect after particle therapy of the skull base. We were able to develop a multivariate model, which predicted radiation reactions with a specificity of 99% and a sensitivity of 52.2%.

A meta-analysis comparing efficacy and safety between proton beam therapy versus carbon ion radiotherapy

BACKGROUND

This study aimed to compare the outcomes of proton beam therapy (PBT) and carbon ion radiotherapy (CIRT) by a systematic review and meta-analysis of the existing clinical evidence.

METHODS

A systematic literature search was performed to identify studies comparing the clinical outcomes of PBT and CIRT. The included studies were required to report oncological outcomes (local control [LC], progression-free survival [PFS], or overall survival [OS]) or adverse events.

RESULTS

Eighteen articles comprising 1857 patients (947 treated with PBT and 910 treated with CIRT) were included in the analysis. The pooled analysis conducted for the overall population yielded average hazard ratios of 0.690 (95% confidence interval (CI), 0.493-0.967, p = 0.031) for LC, 0.952 (95% CI, 0.604-1.500, p = 0.590) for PFS, and 1.183 (0.872-1.607, p = 0.281) for OS with reference to CIRT. The subgroup analyses included patients treated in the head and neck, areas other than the head and neck, and patients with chordomas and chondrosarcomas. These analyses revealed no significant differences in most outcomes, except for LC in the subgroup of patients treated in areas other than the head and neck. Adverse event rates were comparable in both groups, with an odds ratio (OR) of 1.097 (95% CI, 0.744-1.616, p = 0.641). Meta-regression analysis for possible heterogeneity did not demonstrate a significant association between treatment outcomes and the ratio of biologically effective doses between modalities.

CONCLUSION

This study highlighted the comparability of PBT and CIRT in terms of oncological outcomes and adverse events.

Risk Factors for Radiation Necrosis and Local Recurrence after Proton Beam Therapy for Skull Base Chordoma or Chondrosarcoma

[Proposal] Here, we retrospectively evaluate risk factors for radiation necrosis and local recurrence after PBT for skull base chordoma or chondrosarcoma. [Patients and Methods] We analyzed 101 patients who received PBT for skull base chordomas and chondrosarcomas from January 1989 to February 2021. Multivariable logistic regression models were applied for local recurrence, temporal lobe radiation necrosis rates, and temporal lobe radiation necrosis. [Results] In multivariate analysis, chordoma and large tumor size were independent significant factors for local recurrence. The 1-, 2-, 3-, 4- and 5-year local recurrence rates were 3.9%, 16.9%, 20.3%, 28.5% and 44.0% for chordoma and 0%, 0%, 0%, 0% and 7.1% for chondrosarcoma, respectively. The local recurrence rates of small tumors (<30 mm) were 4.3%, 14.7%, 17.7%, 17.7% and 25.9%, and those for large tumors were 3.6%, 15.1%, 19.2%, 32.7% and 59.6%, respectively. In multivariate analysis, BED Gy10 and total dose were risk factors for radiation necrosis. [Conclusions] For skull base chordoma and chondrosarcoma, the risk factors of local recurrence were chordoma and large tumor size, and those of radiation necrosis were BED Gy10 and total dose, respectively. DVH analysis is needed to investigate the risk factors for brain necrosis in more detail.

Radiation Therapy for Chordomas and Chondrosarcomas of the Skull Base: Evaluation of the Effectiveness of Treatment Methods (Review)

Chordomas and chondrosarcomas of the skull base are rare tumors. They are located in close proximity to critical structures, which poses a serious problem in the treatment of these tumors. Despite advances in surgery, radical resection is often not possible. Radiation therapy for chordomas and chondrosarcomas of the skull base is able to improve overall survival and local control. The aim of this review is to analyze the literature data and evaluate the efficacy of radiation therapy techniques for chordomas and chondrosarcomas of the skull base. The most promising methods of radiation therapy for chordomas and chondrosarcomas of the skull base have been shown to be pencil-beam scanning proton therapy with intensity modulation and carbon ion therapy. These techniques have demonstrated high local control and overall survival with a low incidence of severe radiation-induced toxicity, which confirms their clinical benefits. It has also been found that stereotactic radiosurgery can be effectively used for small tumors (less than 7 cm3).

The Role of Carbon Ion Therapy in the Changing Oncology Landscape-A Narrative Review of the Literature and the Decade of Carbon Ion Experience at the Italian National Center for Oncological Hadrontherapy

BACKGROUND

Currently, 13 Asian and European facilities deliver carbon ion radiotherapy (CIRT) for preclinical and clinical activity, and, to date, 55 clinical studies including CIRT for adult and paediatric solid neoplasms have been registered. The National Center for Oncological Hadrontherapy (CNAO) is the only Italian facility able to accelerate both protons and carbon ions for oncological treatment and research.

METHODS

To summarise and critically evaluate state-of-the-art knowledge on the application of carbon ion radiotherapy in oncological settings, the authors conducted a literature search till December 2022 in the following electronic databases: PubMed, Web of Science, MEDLINE, Google Scholar, and Cochrane. The results of 68 studies are reported using a narrative approach, highlighting CNAO's clinical activity over the last 10 years of CIRT.

RESULTS

The ballistic and radiobiological hallmarks of CIRT make it an effective option in several rare, radioresistant, and difficult-to-treat tumours. CNAO has made a significant contribution to the advancement of knowledge on CIRT delivery in selected tumour types.

CONCLUSIONS

After an initial ramp-up period, CNAO has progressively honed its clinical, technical, and dosimetric skills. Growing engagement with national and international networks and research groups for complex cancers has led to increasingly targeted patient selection for CIRT and lowered barriers to facility access.

Efficacy and safety of carbon ion radiotherapy for chordomas: a systematic review and meta-analysis

OBJECTIVE

Carbon ion radiotherapy (C-ion RT) for chordomas has been gradually performed in several research centres. This study aimed to systematically review the results of clinical reports from these institutions and to evaluate the safety and efficacy of C-ion RT.

METHODS

In accordance with the PRISMA guidelines and set search strategies, we searched four databases for articles from their inception to February 11, 2023. These articles were screened, and data were extracted independently by two researchers. STATA 14.0 was used for statistical analysis of survival results.

RESULTS

A total of 942 related articles were retrieved, 11 of which were included. Regarding lesion location, 57% (n = 552) originated in the sacral region, 41% (n = 398) in the skull base, and 2% (n = 19) in the spine (upper cervical). The local control (LC) rates at 1, 2, 3, 5, 9, and 10 years in these studies were 96%, 93%, 83%, 76%, 71%, and 54%, respectively. The overall survival (OS) rates at 1, 2, 3, 5, 9, and 10 years in these studies were 99%, 100%, 93%, 85%, 76%, and 69%, respectively. Acute and late toxicities were acceptable, acute toxicities were mainly grade 1 to grade 2 and late toxicities were mainly grade 1 to grade 3.

CONCLUSION

C-ion RT has attractive clinical application prospects and is an important local treatment strategy for chordomas. Encouraging results were observed in terms of LC and OS. Meanwhile, the acute and late toxicities were acceptable. PROSPERO registration number: CRD42023398792.

Current topics and management of head and neck sarcomas

Given the low incidence, variety of histological types, and heterogeneous biological features of head and neck sarcomas, there is limited high-quality evidence available to head and neck oncologists. For resectable sarcomas, surgical resection followed by radiotherapy is the principle of local treatment, and perioperative chemotherapy is considered for chemotherapy-sensitive sarcomas. They often originate in anatomical border areas such as the skull base and mediastinum, and they require a multidisciplinary treatment approach considering functional and cosmetic impairment. Moreover, head and neck sarcomas may exhibit different behaviour and characteristics than sarcomas of other areas. In recent years, the molecular biological features of sarcomas have been used for the pathological diagnosis and development of novel agents. This review describes the historical background and recent topics that head and neck oncologists should know about this rare tumour from the following five perspectives: (i) epidemiology and general characteristics of head and neck sarcomas; (ii) changes in histopathological diagnosis in the genomic era; (iii) current standard treatment by histological type and clinical questions specific to head and neck; (iv) new drugs for advanced and metastatic soft tissue sarcomas; and (v) proton and carbon ion radiotherapy for head and neck sarcomas.

The role of particle radiotherapy in the treatment of skull base tumors

The skull base is an anatomically and functionally critical area surrounded by vital structures such as the brainstem, the spinal cord, blood vessels, and cranial nerves. Due to this complexity, management of skull base tumors requires a multidisciplinary approach involving a team of specialists such as neurosurgeons, otorhinolaryngologists, radiation oncologists, endocrinologists, and medical oncologists. In the case of pediatric patients, cancer management should be performed by a team of pediatric-trained specialists. Radiation therapy may be used alone or in combination with surgery to treat skull base tumors. There are two main types of radiation therapy: photon therapy and particle therapy. Particle radiotherapy uses charged particles (protons or carbon ions) that, due to their peculiar physical properties, permit precise targeting of the tumor with minimal healthy tissue exposure. These characteristics allow for minimizing the potential long-term effects of radiation exposure in terms of neurocognitive impairments, preserving quality of life, and reducing the risk of radio-induced cancer. For these reasons, in children, adolescents, and young adults, proton therapy should be an elective option when available. In radioresistant tumors such as chordomas and sarcomas and previously irradiated recurrent tumors, particle therapy permits the delivery of high biologically effective doses with low, or however acceptable, toxicity. Carbon ion therapy has peculiar and favorable radiobiological characteristics to overcome radioresistance features. In low-grade tumors, proton therapy should be considered in challenging cases due to tumor volume and involvement of critical neural structures. However, particle radiotherapy is still relatively new, and more research is needed to fully understand its effects. Additionally, the availability of particle therapy is limited as it requires specialized equipment and expertise. The purpose of this manuscript is to review the available literature regarding the role of particle radiotherapy in the treatment of skull base tumors.

Future Perspective: Carbon Ion Radiotherapy for Head and Neck and Skull Base Malignancies

Head and neck and base of skull malignancies are challenging for surgical and radiotherapy treatment due to the density of sensitive tissues. Carbon ion radiotherapy (CIRT) is a form of heavy particle therapy that uses accelerated carbon ions to treat malignancies that may be radioresistant or in challenging anatomic locations. CIRT has an increased biological effectiveness (ie, increased cell killing) at the end of the range of the carbon beam (ie, within the target tissue) but not in the entrance dose. This increased biological effectiveness can overcome the effects of radioresistant tumors, tissue hypoxia, and the need for radiotherapy fractionation.

Proton or Carbon Ion Therapy for Skull Base Chordoma: Rationale and First Analysis of a Mono-Institutional Experience

Background: Skull base chordomas are radio-resistant tumors that require high-dose, high-precision radiotherapy, as can be delivered by particle therapy (protons and carbon ions). We performed a first clinical outcome analysis of particle therapy based on the initial 4-years of operation. Methods: Between August 2017 and October 2021, 44 patients were treated with proton (89%) or carbon ion therapy (11%). Prior gross total resection had been performed in 21% of lesions, subtotal resection in 57%, biopsy in 12% and decompression in 10%. The average prescription dose was 75.2 Gy RBE in 37 fractions for protons and 66 Gy RBE in 22 fractions for carbon ions. Results: At a median follow-up of 34.3 months (range: 1–55), 2-, and 3-year actuarial local control rates were 95.5% and 90.9%, respectively. The 2-, and 3-year overall and progression-free survival rates were 97.7%, 93.2%, 95.5% and 90.9%, respectively. The tumor volume at the time of particle therapy was highly predictive of local failure (p < 0.01), and currently, there is 100% local control in patients with tumors < 49 cc. No grade ≥3 toxicities were observed. There was no significant difference in outcome or side effect profile seen for proton versus carbon ion therapy. Five patients (11.4%) experienced transient grade ≤2 radiation-induced brain changes. Conclusions: The first analysis suggests the safety and efficacy of proton and carbon ion therapy at our center. The excellent control of small to mid-size chordomas underlines the effectiveness of particle therapy and importance of upfront maximum debulking of large lesions.

Microstructural parameters from DW-MRI for tumour characterization and local recurrence prediction in particle therapy of skull-base chordoma

BACKGROUND

Quantitative imaging such as Diffusion-Weighted MRI (DW-MRI) can be exploited to non-invasively derive patient-specific tumor microstructure information for tumor characterization and local recurrence risk prediction in radiotherapy.

PURPOSE

To characterize tumor microstructure according to proliferative capacity and predict local recurrence through microstructural markers derived from pre-treatment conventional DW-MRI, in skull-base chordoma (SBC) patients treated with proton (PT) and carbon ion (CIRT) radiotherapy.

METHODS

Forty-eight patients affected by SBC, who underwent conventional DW-MRI before treatment and were enrolled for CIRT (n = 25) or PT (n = 23), were retrospectively selected. Clinically verified local recurrence information (LR) and histological information (Ki-67, proliferation index) were collected. Apparent diffusion coefficient (ADC) maps were calculated from pre-treatment DW-MRI and, from these, a set of microstructural parameters (cellular radius R, volume fraction vf, diffusion D) were derived by applying a fine-tuning procedure to a framework employing Monte Carlo simulations on synthetic cell substrates. In addition, apparent cellularity (ρ_app ) was estimated from vf and R for an easier clinical interpretation. Histogram-based metrics (mean, median, variance, entropy) from estimated parameters were considered to investigate differences (Mann-Whitney U-test, α = 0.05) in estimated tumor microstructure in SBCs characterized by low or high cell proliferation (Ki-67). Recurrence-free survival analyses were also performed to assess the ability of the microstructural parameters to stratify patients according to the risk of local recurrence (Kaplan-Meier curves, log-rank test α = 0.05).

RESULTS

Refined microstructural markers revealed optimal capabilities in discriminating patients according to cell proliferation, achieving best results with mean values (p-values were 0.0383, 0.0284, 0.0284, 0.0468, and 0.0088 for ADC, R, vf, D, and ρ_app, respectively). Recurrence-free survival analyses showed significant differences between populations at high and low risk of local recurrence as stratified by entropy values of estimated microstructural parameters (p = 0.0110).

CONCLUSION

Patient-specific microstructural information was non-invasively derived providing potentially useful tools for SBC treatment personalization and optimization in particle therapy.

Proton and carbon ion beam treatment with active raster scanning method in 147 patients with skull base chordoma at the Heidelberg Ion Beam Therapy Center-a single-center experience

BACKGROUND

This study aimed to compare the results of irradiation with protons versus irradiation with carbon ions in a raster scan technique in patients with skull base chordomas and to identify risk factors that may compromise treatment results.

METHODS

A total of 147 patients (85 men, 62 women) were irradiated with carbon ions (111 patients) or protons (36 patients) with a median dose of 66 Gy (RBE (Relative biological effectiveness); carbon ions) in 4 weeks or 74 Gy (RBE; protons) in 7 weeks at the Heidelberg Ion Beam Therapy Center (HIT) in Heidelberg, Germany. The median follow-up time was 49.3 months. All patients had gross residual disease at the beginning of RT. Compression of the brainstem was present in 38%, contact without compression in 18%, and no contact but less than 3 mm distance in 16%. Local control and overall survival were evaluated using the Kaplan-Meier Method based on scheduled treatment (protons vs. carbon ions) and compared via the log rank test. Subgroup analyses were performed to identify possible prognostic factors.

RESULTS

During the follow-up, 41 patients (27.9%) developed a local recurrence. The median follow-up time was 49.3 months (95% CI: 40.8-53.8; reverse Kaplan-Meier median follow-up time 56.3 months, 95% CI: 51.9-60.7). No significant differences between protons and carbon ions were observed regarding LC, OS, or overall toxicity. The 1‑year, 3‑year, and 5‑year LC rates were 97%, 80%, and 61% (protons) and 96%, 80%, and 65% (carbon ions), respectively. The corresponding OS rates were 100%, 92%, and 92% (protons) and 99%, 91%, and 83% (carbon ions). No significant prognostic factors for LC or OS could be determined regarding the whole cohort; however, a significantly improved LC could be observed if the tumor was > 3 mm distant from the brainstem in patients presenting in a primary situation.

CONCLUSION

Outcomes of proton and carbon ion treatment of skull base chordomas seem similar regarding tumor control, survival, and toxicity. Close proximity to the brainstem might be a negative prognostic factor, at least in patients presenting in a primary situation.

3D-printed guides for cervical pedicle screw placement in primary spine tumor: Case report and technical description

Introduction

For spine surgeons, dealing with unstable cervical spine has been usually challenging, and this becomes more difficult when facing a primary craniovertebral junction tumor. Primary spine tumor surgery should always include column reconstruction in order to guarantee biomechanical stability of the spine, but surgeons should always be aware that instrumentations could create interferences with postoperative radiations. However, although carbon fiber instrumentations have started to be used in thoracolumbar oncology for few years, these options are still not available for cervical spine. In the reported case, the adopted strategy to obtain adequate column reconstruction was based on the idea of reducing the amount of titanium needed for posterior fixation and maximizing the distance between the radiation target and titanium rods.

Case report and aim

We present the case of a 53-year-old woman harboring a craniovertebral junction chordoma. A short occipito-C3 construct was selected. Specifically, titanium cervical pedicle screws were placed by using a new technology consisting in patient-tailored and customized 3D-printed guides. The aim of this case report is to determine the feasibility and safety of 3D-printed guides for cervical pedicle screw (CPS) positioning, even in the case of cervical spine tumor.

Conclusion

CPS could represent a good solution by providing strong biomechanical purchase and tailored 3D-printed guides could increase the safety and the accuracy of this challenging screw placement, even in oncological patients.

Outcomes of Gamma Knife radiosurgery for skull base chondrosarcomas: a multi-institutional retrospective study

OBJECTIVE

Radiotherapy has an essential role in the management of skull base chondrosarcomas (SBCs) after resection. This multi-institutional study evaluated the outcomes of Gamma Knife radiosurgery (GKRS) for histopathologically proven SBCs.

METHODS

Data of patients who underwent GKRS for SBCs at Gamma Knife centers in Japan were retrospectively collected. Patients without a histopathological diagnosis and those who had intracranial metastases from extracranial chondrosarcomas were excluded. Histologically, grade III and some nonconventional variants were identified as aggressive types. The cumulative local control rates (LCRs) and disease-specific survival (DSS) rates were calculated using the Kaplan-Meier method. Factors potentially affecting the LCR were evaluated using the Cox proportional hazards model for bivariate and multivariate analyses. The incidence of radiation-induced adverse effects (RAEs) was calculated as crude rates, and factors associated with RAEs were examined using Fisher's exact test.

RESULTS

Fifty-one patients were enrolled, with a median age of 38 years. Thirty patients (59%) were treated with upfront GKRS for residual SBCs after resection (n = 27) or biopsy (n = 3), and 21 (41%) underwent GKRS as a salvage treatment for recurrence. The median tumor volume was 8 cm3. The overall LCRs were 87% at 3 years, 78% at 5 years, and 67% at 10 years after GKRS. A better LCR was associated with a higher prescription dose (p = 0.039) and no history of repeated recurrence before GKRS (p = 0.024). The LCRs among patients with the nonaggressive histological type and treatment with ≥ 16 Gy were 88% at 3 years, 83% at 5 years, and 83% at 10 years. The overall survival rates after GKRS were 96% at 5 years and 83% at 10 years. Although RAEs were observed in 3 patients (6%), no severe RAEs with Common Terminology Criteria for Adverse Events grade 3 or higher were identified. No significant factor was associated with RAEs.

CONCLUSIONS

GKRS for SBCs has a favorably low risk of RAEs and could be a reasonable therapeutic option for SBC in multimodality management. A sufficient GKRS prescription dose is necessary for higher LCRs. Histological grading and subtype evaluations are important for excluding exceptional SBCs. Patients with conventional SBCs have a long life expectancy and should be observed for life after treatment.

Single-cell transcriptome reveals cellular hierarchies and guides p-EMT-targeted trial in skull base chordoma

Skull base chordoma (SBC) is a bone cancer with a high recurrence rate, high radioresistance rate, and poorly understood mechanism. Here, we profiled the transcriptomes of 90,691 single cells, revealed the SBC cellular hierarchies, and explored novel treatment targets. We identified a cluster of stem-like SBC cells that tended to be distributed in the inferior part of the tumor. Combining radiated UM-Chor1 RNA-seq data and in vitro validation, we further found that this stem-like cell cluster is marked by cathepsin L (CTSL), a gene involved in the packaging of telomere ends, and may be responsible for radioresistance. Moreover, signatures related to partial epithelial-mesenchymal transition (p-EMT) were found to be significant in malignant cells and were related to the invasion and poor prognosis of SBC. Furthermore, YL-13027, a p-EMT inhibitor that acts through the TGF-β signaling pathway, demonstrated remarkable potency in inhibiting the invasiveness of SBC in preclinical models and was subsequently applied in a phase I clinical trial that enrolled three SBC patients. Encouragingly, YL-13027 attenuated the growth of SBC and achieved stable disease with no serious adverse events, underscoring the clinical potential for the precision treatment of SBC with this therapy. In summary, we conducted the first single-cell RNA sequencing of SBC and identified several targets that could be translated to the treatment of SBC.

Long-term outcomes of high dose carbon-ion radiation therapy for unresectable upper cervical (C1-2) chordoma

Background

Chordoma is a rare, locally invasive neoplasm of the axial skeleton. Complete resection is often difficult, especially for the upper‐cervical (C1‐2) spine. We evaluated the efficacy and safety of carbon‐ion radiotherapy (CIRT) for unresectable C1‐2 chordoma.

Methods

Patients with C1‐2 chordoma treated with definitive CIRT (60.8 Gy [RBE] in 16 fractions) were retrospectively analyzed. We evaluated OS, LC, PFS, and toxicity.

Results

Nineteen eligible patients all completed the planned course of CIRT. With the median follow‐up 68 months (range: 29–144), median OS was 126 months (range: 36‐NA). Five‐year OS, LC, and PFS were 68.4% (95% CI, 42.8%–84.4%), 75.2% (46.1%–90.0%), and 64.1% (36.3%–82.3%), respectively. Regarding acute toxicity of grade ≥3, there was only one grade 3 mucositis. Late toxicity included radiation‐induced myelitis (grade 3 in 1 patient; 5.3%), and compression fractures (n = 5; 26.3%).

Conclusions

High‐dose CIRT is a promising treatment option for unresectable upper cervical chordoma.

Hadron Therapy Achievements and Challenges: The CNAO Experience

Protons and carbon ions (hadrons) have useful properties for the treatments of patients affected by oncological pathologies. They are more precise than conventional X-rays and possess radiobiological characteristics suited for treating radio-resistant or inoperable tumours. This paper gives an overview of the status of hadron therapy around the world. It focusses on the Italian National Centre for Oncological Hadron therapy (CNAO), introducing operation procedures, system performance, expansion projects, methodologies and modelling to build individualized treatments. There is growing evidence that supports safety and effectiveness of hadron therapy for a variety of clinical situations. However, there is still a lack of high-level evidence directly comparing hadron therapy with modern conventional radiotherapy techniques. The results give an overview of pre-clinical and clinical research studies and of the treatments of 3700 patients performed at CNAO. The success and development of hadron therapy is strongly associated with the creation of networks among hadron therapy facilities, clinics, universities and research institutions. These networks guarantee the growth of cultural knowledge on hadron therapy, favour the efficient recruitment of patients and present available competences for R&D (Research and Development) programmes.

Impact of Treatment Modalities upon Survival Outcomes in Skull Base and Clival Chordoma: An NCDB Analysis

Objectives  Skull base chordomas are locally aggressive malignant tumors derived from the notochord remnant. There are limited large-scale studies examining the role and extent of surgery and radiation therapy. Design  Analysis of the National Cancer Database (NCDB) was performed to evaluate the survival outcomes of various treatments, and to assess for predictors of overall survival (OS). Participants  This is a retrospective, population-based cohort study of patients diagnosed with a clival/skull base chordoma between 2004 and 2015 in the NCDB. Main Outcome Measures  The primary outcome was overall survival (OS). Results  In all, 468 cases were identified. Forty-nine percent of patients received surgery and 20.7% had positive margins. Mean age at diagnosis was 48.4 years in the surgical cohort, and 55% were males. Of the surgical cohort, 33.8% had negative margins, 20.7% had positive margins, and 45.5% had unknown margin status. Age ≥ 65 (hazard ratio [HR]: 3.07; 95% confidence interval [CI]: 1.63-5.76; p  < 0.001), diagnosis between 2010 and 2015 (HR: 0.49; 95% CI: 0.26-0.90; p  = 0.022), tumor size >5 cm (HR: 2.29; 95% CI: 1.26-4.15; p  = 0.007), and government insurance (HR: 2.28; 95% CI: 1.24-4.2; p  = 0.008) were independent predictors of OS. When comparing surgery with or without adjuvant radiation, no survival differences were found, regardless of margin status ( p  = 0.66). Conclusion  Surgery remains the mainstay of therapy. Advanced age (>65 years), large tumor size, and government insurance were predictors of worse OS. Whereas negative margins and the use of adjuvant radiation did not appear to impact OS, these may very well reduce local recurrences. A multidisciplinary approach is critical in achieving optimal outcomes in this challenging disease.

Two-Year Toxicity and Efficacy of Carbon Ion Radiotherapy in the Treatment of Localized Prostate Cancer: A Single-Centered Study

Background

We aimed at determining the safety and feasibility of spot-scanning carbon ion radiotherapy (CIRT) for patients with localized prostate cancer.

Methods

We enrolled 118 patients with localized prostate cancer who underwent treatment with spot-scanning CIRT at the Shanghai Proton and Heavy Ion Center (SPHIC) from January 2016 to December 2020. The dose was gradually increased from relative biological effectiveness (RBE)-weighted dose (D_RBE) = 59.2–65.6 Gy in 16 fractions. The primary endpoint was the occurrence of acute and late toxicities, while the secondary endpoints were biochemical relapse-free survival (bRFS), distant metastasis-free survival (DMFS), prostate cancer-specific survival (PCSS), and overall survival (OS).

Results

The median follow-up time was 30.2 months (4.8–62.7 months). Acute grade 1 and 2 genitourinary (GU) toxicities were 15.3% and 18.6%, while acute grade 1 and 2 gastrointestinal (GI) toxicities were 2.5% and 0%, respectively. Late grade 1 and 2 GU toxicities were 4.2% and 1.7%, respectively. No late GI toxicity was observed. Moreover, there were no cases of severe acute or late toxicity (≥ grade 3). No significant association were observed between the factors and the acute GU toxicities, except for clinical target volume (CTV) (p = 0.031) on multivariate analysis. The 2-year bRFS, DMFS, PCSS, and OS were 100%, 100%, 100%, and 98.8%, respectively.

Conclusion

The 2-year outcomes were encouraging, providing additional and useful information on the feasibility and safety of spot-scanning CIRT for treating prostate cancer. Thus, we recommend long-term follow-up and prospective multicentered studies to reinforce the role of CIRT in the management of localized prostate cancer.

Analysis of tumour microstructure estimation from conventional diffusion MRI and application to skull-base chordoma. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2021;2021:3761-3764. [PMID: 34892054 DOI: 10.1109/embc46164.2021.9630129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Skull-base chordoma (SBC) is a rare tumour whose molecular and radiological characteristics are still being investigated. In neuro-oncology microstructural imaging techniques, like diffusion-weighted MRI (DW-MRI), have been widely investigated, with the apparent diffusion coefficient (ADC) being one of the most used DW-MRI parameters due to its ease of acquisition and computation. ADC is a potential biomarker without a clear link to microstructure. The aim of this work was to derive microstructural information from conventional ADC, showing its potential for the characterisation of skull-base chordomas. Sixteen patients affected by SBC, who underwent conventional DW-MRI were retrospectively selected. From mono-exponential fits of DW-MRI, ADC maps were estimated using different sets of b-values. DW-MRI signals were simulated from synthetic substrates , which mimic the cellular packing of a tumour tissue with well-defined microstructural features. Starting from a published method, an error-driven procedure was evaluated to improve the estimates of microstructural parameters obtained through the simulated signals. A quantitative description of the tumour microstructure was then obtained from the DW-MRI images. This allowed successfully differentiating patients according to histologically-verified cell proliferation information.Clinical Relevance - The impact on cancer management derives from the expected improvement of radiation treatment quality tailored to a patient-specific non-invasive description of tumour microstructure.

Particle Beam Therapy Tolerance and Outcome on Patients with Autoimmune Diseases: A Single Institution Matched Case-Control Study

It is unclear whether autoimmune diseases (ADs) may predispose patients to higher radiation-induced toxicity, and no data are available regarding particle therapy. Our objective was to determine if cancer patients with ADs have a higher incidence of complications after protons (PT) or carbon ion (CIRT) therapy.

METHODS

In our retrospective monocentric study, 38 patients with ADs over 1829 patients were treated with particle therapy between 2011 and 2020. Thirteen patients had collagen vascular disease (CVD), five an inflammatory bowel disease (IBD) and twenty patients an organ-specific AD. Each patient was matched with two control patients without ADs on the basis of type/site of cancer, type of particle treatment, age, sex, hypertension and/or diabetes and previous surgery.

RESULTS

No G4-5 complications were reported. In the AD group, the frequency of acute grade 3 (G3) toxicity was higher than in the control group (15.8% vs. 2.6%, p = 0.016). Compared to their matched controls, CVD-IBD patients had a higher frequency of G3 acute complications (27.7 vs. 2.6%, p = 0.002). There was no difference between AD patients (7.9%) and controls (2.6%) experiencing late G3 toxicity (p = 0.33). The 2 years disease-free survival was lower in AD patients than in controls (74% vs. 91%, p = 0.01), although the differences in terms of survival were not significant.

CONCLUSIONS

G3 acute toxicity was more frequently reported in AD patients after PT or CIRT. Since no severe G4-G5 events were reported and in consideration of the benefit of particle therapy for selected cancers, we conclude that particle therapy should be not discouraged for patients with ADs. Further prospective studies are warranted to gain insight into toxicity in cancer patients with ADs enrolled for particle therapy.

Craniovertebral junction chordomas: Case series and strategies to overcome the surgical challenge

Introduction:

Chordomas are rare and malignant primary bone tumors. Different strategies have been proposed for chordomas involving the craniovertebral junction (CVJ) compared to other locations. The impossibility to achieve en bloc excision, the impact on stability and the need for proper reconstruction make their surgical management challenging.

Objective:

The objective is to discuss surgical strategies in CVJ chordomas operated in a single-center during a 7 years' experience (2013-2019).

Methods:

Adult patients with CVJ chordoma were retrospectively analyzed. The clinical, radiological, pathological, and surgical data were discussed.

Results:

A total number of 8 patients was included (among a total number of 32 patients suffering from skull base chordoma). Seven patients underwent endoscopic endonasal approach (EEA), and posterior instrumentation was needed in three cases. Three explicative cases were reported: EEA for midline tumor involving lower clivus and upper cervical spine (case 1), EEA and complemental posterior approach for occurred occipitocervical instability (case 2), C2 chordoma which required aggressive bone removal and consequent implant positioning, focusing on surgical planning (timing and type of surgical stages, materials and customization of fixation system) (case 3).

Conclusion:

EEA could represent a safe route to avoid injuries to neurovascular structure in clival locations, while a combined approach could be considered when tumor spreads laterally. Tumor involvement or surgical procedures could give raise to CVJ instability with the need of complementary posterior instrumentation. Thus, a tailored preoperative planning should play a key role, especially when aggressive bone removal and implant positioning are needed.

Potential role of functional imaging in predicting outcome for patients treated with carbon ion therapy: a review

OBJECTIVE

Carbon ion radiation therapy (CIRT) is an emerging radiation technique with advantageous physical and radiobiologic properties compared to conventional radiotherapy (RT) providing better response in case of radioresistant and hypoxic tumors. Our aim is to critically review if functional imaging techniques could play a role in predicting outcome of CIRT-treated tumors, as already proven for conventional RT.

METHODS

14 studies, concerning Magnetic resonance imaging (MRI) and Positron Emission Tomography (PET), were selected after a comprehensive search on multiple electronic databases from January 2000 to March 2020.

RESULTS

MRI studies (n = 5) focused on diffusion-weighted MRI and, even though quantitative parameters were the same in all studies (apparent diffusion coefficient, ADC), results were not univocal, probably due to different imaging acquisition protocols and tumoral histology. For PET studies (n = 9), different tracers were used such as [¹⁸F]FDG and other uncommon tracers ([¹¹C]MET, [¹⁸F]FLT), with a relevant heterogeneity regarding parameters used for outcome assessment.

CONCLUSION

No conclusion can be drawn on the predictive value of functional imaging in CIRT-treated tumors. A standardization of image acquisition, multi-institutional large trials and external validations are needed in order to establish the prognostic value of functional imaging in CIRT and to guide clinical practice.

ADVANCES IN KNOWLEDGE

Emerging studies focused on functional imaging's role in predicting CIRT outcome. Due to the heterogeneity of images acquisition and studies, results are conflicting and prospective large studies with imaging standardized protocol are needed.

How LEM-based RBE and dose-averaged LET affected clinical outcomes of sacral chordoma patients treated with carbon ion radiotherapy

PURPOSE/OBJECTIVE

To understand the role of relative biological effectiveness (RBE) and dose-averaged linear energy transfer (LET_d) distributions in the treatment of sacral chordoma (SC) patients with carbon ion radiotherapy (CIRT).

MATERIAL/METHODS

Clinical plans of 50 SC patients consecutively treated before August 2018 with a local effect model-based optimization were recalculated with the modified microdosimetric kinetic RBE model (mMKM). Twenty-six patients were classified as progressive disease and the relapse volume was contoured on the corresponding follow-up diagnostic sequence. The remaining 24 patients populated the control group. Target prescription dose (D_RBE|50%), near-to-minimum- (D_RBE|95%) and near-to-maximum- (D_RBE|2%) doses were compared between the two cohorts in both RBE systems. LET_d distribution was evaluated for in-field relapsed cases with respect to the control group.

RESULTS

Target D_MKM|50% and D_MKM|95% were respectively 10% and 18% lower than what we aimed at. Dosimetric evaluators showed no significant difference, in neither of the RBE frameworks, between relapsed and control sets. Half of the relapse volumes were located in a well-covered high dose region. On average, over these cases, median target LET_d was significantly lower than the control cohort mean value (27 vs 30 keV/μm). Most notably, the volume receiving dose from high-LET particles (>50 keV/μm) lay substantially below recently reported data in the literature.

CONCLUSION

A combined multi model RBE- and LET-based optimization could play a key role in the enhancement of the therapeutic ratio of CIRT for large radioresistant tumors such as sacral chordomas.

Clinicopathological and Prognostic Characteristics in Dedifferentiated/Poorly Differentiated Chordomas: A Pooled Analysis of Individual Patient Data From 58 Studies and Comparison With Conventional Chordomas

Background

Currently, the clinicopathological and prognostic characteristics of dedifferentiated chordoma (DC) and poorly differentiated chordoma (PDC) remain poorly understood. In this study, we sought to characterize clinicopathological parameters in a large PDC/DC cohort and determine their correlations with progression-free survival (PFS) and overall survival (OS) of patients. We also attempted to compare clinical features between PDC/DC and conventional chordoma (CC).

Methods

Literature searches (from inception to June 01, 2020) using Medline, Embase, Google Scholar and Wanfang databases were conducted to identify eligible studies according to predefined criteria. The local database at our center was also retrospectively reviewed to include CC patients for comparative analysis.

Results

Fifty-eight studies from the literature and 90 CC patients from our local institute were identified; in total, 54 PDC patients and 96 DC patients were analyzed. Overall, PDC or DC had distinct characteristics from CC, while PDC and DC shared similar clinical features. Adjuvant radiotherapy and chemotherapy were associated with both PFS and OS in PDC patients in the univariate and/or multivariate analyses. In the DC cohort, tumor resection type, adjuvant chemotherapy and tumor dedifferentiation components significantly affected PFS, whereas none of them were predictive of outcome in the multivariate analysis. By analyzing OS, we found that surgery, resection type and the time to dedifferentiation predicted the survival of DC patients; however, only surgery remained significant after adjusting for other covariables.

Conclusions

These data may offer useful information to better understand the clinical characteristics of PDC/DC and may be helpful in improving the outcome prediction of patients.

Particle Radiotherapy for Skull Base Chondrosarcoma: A Clinical Series from Italian National Center for Oncological Hadrontherapy

Simple Summary

Skull-base chondrosarcoma is a rare locally aggressive or malignant group of cartilaginous neoplasm. The standard of care consists of surgery and high-dose radiation therapy, better if with particle, due to their radioresistance and proximity to organs at risk such as brainstem and optic pathways. Due to the rarity of the tumor and its site, outcomes in terms of local control and toxicity of patients with this malignancy after receiving particle therapy has been documented only in a limited number of series with a restricted number of patients, in particular with regard to carbon ions. The aim of our retrospective study is to assess the role of particle therapy (protons and carbon ions) after surgery in our Institute in skull-base chondrosarcomas.

Abstract

Background: The standard treatment for skull base chondrosarcoma (SB-CHS) consists of surgery and high-dose radiation therapy. Our aim was to evaluate outcome in terms of local control (LC) and toxicity of proton therapy (PT) and carbon ion (CIRT) after surgery. Materials and methods: From September 2011 to July 2020, 48 patients underwent particle therapy (67% PT, 33% CIRT) for SB-CHS. PT and CIRT total dose was 70 GyRBE (relative biological effectiveness) in 35 fractions and 70.4 GyRBE in 16 fractions, respectively. Toxicity was assessed using the Common Terminology Criteria for Adverse Events (CTCAE v5). Results: After a median follow-up time of 38 months, one local failure (2%) was documented and the patient died for progressive disease. Overall, 3-year LC was 98%. One (2%) and 4 (8%) patients experienced G3 acute and late toxicity, respectively. White-matter brain changes were documented in 22 (46%) patients, but only 7 needed steroids (G2). No patients had G3 brain toxicity. No G4–5 complications were reported. We did not find any correlation between high-grade toxicity or white-matter changes and characteristics of patients, disease and surgery. Conclusions: PT and CIRT appeared to be effective and safe treatments for patients with SB-CHS, resulting in high LC rates and an acceptable toxicity profile.

Chordoma: Current status, problems, and future directions

Chordoma is a rare tumor that occurs along the axial spine in pediatrics and adults, with an incidence of approximately 350 cases per year in the United States. While typically described as slow-growing, many patients will eventually develop loco-regional relapse or metastatic disease with few treatment options. Despite numerous efforts over the last 10+ years, effective treatments for patients are lacking. As subtypes of chordoma are identified and described in more detail, further knowledge regarding the natural history of each type, tumor location, age differences, genomic variability, and an overall better understanding of chordoma may be the key to developing meaningful clinical trials and effective therapies for patients with chordoma.

A Review of Particle Therapy for Skull Base Tumors: Modern Considerations and Future Directions

Skull base tumors constitute one of the established indications for particle therapy, specifically proton therapy. However, a number of prognostic factors, practical clinical management issues, and the emerging role of carbon ion therapy remain subjects of active clinical investigation. This review summarizes these topics, assesses the present status, and reflects on future research directions focusing on the management of chordomas, one of the most aggressive skull base tumors. In addition, the role of particle therapy for benign tumors of the skull base, including pituitary adenoma and acoustic neuroma, is reviewed.

Sinonasal cancers treatments: state of the art

PURPOSE OF REVIEW

The present review provides the reader with the state-of-the-art concepts of sinonasal oncology in view of the latest literature data.

RECENT FINDINGS

Most recent publications in sinonasal oncology assessed treatment timing, centralization, surgical approach, margin status, orbit/neck management, salvage strategies, emerging surgical technologies, intensity-modulated radiation therapy (IMRT), volumetric modulated arc therapy (VMAT), particle radiotherapy, and neoadjuvant chemotherapy.

SUMMARY

Indications to endoscopic surgery for sinonasal cancer have plateaued and are unlikely to further expand. Endoscopic surgery provides noninferior results compared to open surgery and best suits timing constraints imposed by multimodal treatment. Management of orbit-encroaching sinonasal cancer is remarkably improving mostly owing to optimal use of nonsurgical strategies. Prognostic value of the margin status and management of the nodal basin and recurrent sinonasal tumors are far from being fully elucidated. Most promising surgical technologies are surgical navigation, optical imaging, and radiofrequency-aided ablation. IMRT and VMAT have theoretical technical advantages that are in the process of being clinically demonstrated. Pieces of evidence are progressively confirming the physical and radiobiological advantages offered by particle radiotherapy. Systemic therapy is being tested mostly in the neoadjuvant setting with the aim of improving outcomes in locally advanced sinonasal cancers; response to induction chemotherapy could better select a further locoregional approach.

Chordoma-Current Understanding and Modern Treatment Paradigms

Chordoma is a low-grade notochordal tumor of the skull base, mobile spine and sacrum which behaves malignantly and confers a poor prognosis despite indolent growth patterns. These tumors often present late in the disease course, tend to encapsulate adjacent neurovascular anatomy, seed resection cavities, recur locally and respond poorly to radiotherapy and conventional chemotherapy, all of which make chordomas challenging to treat. Extent of surgical resection and adequacy of surgical margins are the most important prognostic factors and thus patients with chordoma should be cared for by a highly experienced, multi-disciplinary surgical team in a quaternary center. Ongoing research into the molecular pathophysiology of chordoma has led to the discovery of several pathways that may serve as potential targets for molecular therapy, including a multitude of receptor tyrosine kinases (e.g., platelet-derived growth factor receptor [PDGFR], epidermal growth factor receptor [EGFR]), downstream cascades (e.g., phosphoinositide 3-kinase [PI3K]/protein kinase B [Akt]/mechanistic target of rapamycin [mTOR]), brachyury—a transcription factor expressed ubiquitously in chordoma but not in other tissues—and the fibroblast growth factor [FGF]/mitogen-activated protein kinase kinase [MEK]/extracellular signal-regulated kinase [ERK] pathway. In this review article, the pathophysiology, diagnosis and modern treatment paradigms of chordoma will be discussed with an emphasis on the ongoing research and advances in the field that may lead to improved outcomes for patients with this challenging disease.

Radiomics and Dosiomics for Predicting Local Control after Carbon-Ion Radiotherapy in Skull-Base Chordoma

Skull-base chordoma (SBC) can be treated with carbon ion radiotherapy (CIRT) to improve local control (LC). The study aimed to explore the role of multi-parametric radiomic, dosiomic and clinical features as prognostic factors for LC in SBC patients undergoing CIRT. Before CIRT, 57 patients underwent MR and CT imaging, from which tumour contours and dose maps were obtained. MRI and CT-based radiomic, and dosiomic features were selected and fed to two survival models, singularly or by combining them with clinical factors. Adverse LC was given by in-field recurrence or tumour progression. The dataset was split in development and test sets and the models' performance evaluated using the concordance index (C-index). Patients were then assigned a low- or high-risk score. Survival curves were estimated, and risk groups compared through log-rank tests (after Bonferroni correction α = 0.0083). The best performing models were built on features describing tumour shape and dosiomic heterogeneity (median/interquartile range validation C-index: 0.80/024 and 0.79/0.26), followed by combined (0.73/0.30 and 0.75/0.27) and CT-based models (0.77/0.24 and 0.64/0.28). Dosiomic and combined models could consistently stratify patients in two significantly different groups. Dosiomic and multi-parametric radiomic features showed to be promising prognostic factors for LC in SBC treated with CIRT.

Brainstem NTCP and Dose Constraints for Carbon Ion RT-Application and Translation From Japanese to European RBE-Weighted Dose

Background and Purpose

The Italian National Center of Oncological Hadrontherapy (CNAO) has applied dose constraints for carbon ion RT (CIRT) as defined by Japan’s National Institute of Radiological Sciences (NIRS). However, these institutions use different models to predict the relative biological effectiveness (RBE). CNAO applies the Local Effect Model I (LEM I), which in most clinical situations predicts higher RBE than NIRS’s Microdosimetric Kinetic Model (MKM). Equal constraints therefore become more restrictive at CNAO. Tolerance doses for the brainstem have not been validated for LEM I-weighted dose (D_{LEM I}). However, brainstem constraints and a Normal Tissue Complication Probability (NTCP) model were recently reported for MKM-weighted dose (D_MKM), showing that a constraint relaxation to D_{MKM|0.7 cm³} <30 Gy (RBE) and D_{MKM|0.1 cm³} <40 Gy (RBE) was feasible. The aim of this work was to evaluate the brainstem NTCP associated with CNAO’s current clinical practice and to propose new brainstem constraints for LEM I-optimized CIRT at CNAO.

Material and Methods

We reproduced the absorbed dose of 30 representative patient treatment plans from CNAO. Subsequently, we calculated both D_{LEM I} and D_MKM, and the relationship between D_MKM and D_{LEM I} for various brainstem dose metrics was analyzed. Furthermore, the NTCP model developed for D_MKM was applied to estimate the NTCPs of the delivered plans.

Results

The translation of CNAO treatment plans to D_MKM confirmed that the former CNAO constraints were conservative compared with D_MKM constraints. Estimated NTCPs were 0% for all but one case, in which the NTCP was 2%. The relationship D_MKM/D_{LEM I} could be described by a quadratic regression model which revealed that the validated D_MKM constraints corresponded to D_{LEM I|0.7 cm³} <41 Gy (RBE) (95% CI, 38–44 Gy (RBE)) and D_{LEM I|0.1 cm³} <49 Gy (RBE) (95% CI, 46–52 Gy (RBE)).

Conclusion

Our study demonstrates that RBE-weighted dose translation is of crucial importance in order to exchange experience and thus harmonize CIRT treatments globally. To mitigate uncertainties involved, we propose to use the lower bound of the 95% CI of the translation estimates, i.e., D_{LEM I|0.7 cm³} <38 Gy (RBE) and D_{LEM I|0.1 cm³} <46 Gy (RBE) as brainstem dose constraints for 16 fraction CIRT treatments optimized with LEM I.