Cranial Chordoma: A New Preoperative Grading System

Chordoma: Genetics and Contemporary Management

Chordomas, arising from notochord remnants, are rare neoplasms with aggressive growth patterns despite their histologically low-grade nature. This review explores their embryological origins, molecular markers like brachyury, and genetic alterations driving pathogenesis. Diagnosis relies on advanced imaging and biopsy confirmation due to overlapping features with chondrosarcoma. The WHO classification distinguishes conventional, dedifferentiated, and poorly differentiated chordomas, each with distinct prognostic implications. Recent genomic analyses uncovered recurrent mutations in PI3K signaling pathways and chromatin remodeling genes, informing prognostic models. Surgery remains the cornerstone of treatment, though adjuvant radiation complements surgical resection. Although chordomas are generally considered refractory to medical therapy, emerging targeted molecular strategies show potential promise in ongoing trials. This review aims to provide a concise yet comprehensive overview of chordomas, guiding clinicians in diagnosis, treatment, and prognostication for improved patient outcomes.

Predicting overall survival in chordoma patients using machine learning models: a web-app application

OBJECTIVE

The goal of this study was to evaluate the efficacy of machine learning (ML) techniques in predicting survival for chordoma patients in comparison with the standard Cox proportional hazards (CoxPH) model.

METHODS

Using a Surveillance, Epidemiology, and End Results database of consecutive newly diagnosed chordoma cases between January 2000 and December 2018, we created and validated three ML survival models as well as a traditional CoxPH model in this population-based cohort study. Randomly, the dataset was divided into training and validation datasets. Tuning hyperparameters on the training dataset involved a 1000-iteration random search with fivefold cross-validation. Concordance index (C-index), Brier score, and integrated Brier score were used to evaluate the performance of the model. The receiver operating characteristic (ROC) curves, calibration curves, and area under the ROC curves (AUC) were used to assess the reliability of the models by predicting 5- and 10-year survival probabilities.

RESULTS

A total of 724 chordoma patients were divided into training (n = 508) and validation (n = 216) cohorts. Cox regression identified nine significant prognostic factors (p < 0.05). ML models showed superior performance over CoxPH model, with DeepSurv having the highest C-index (0.795) and the best discrimination for 5- and 10-year survival (AUC 0.84 and 0.88). Calibration curves revealed strong correlation between DeepSurv predictions and actual survival. Risk stratification by DeepSurv model effectively discriminated high- and low-risk groups (p < 0.01). The optimized DeepSurv model was implemented into a web application for clinical use that can be found at https://hust-chengp-ml-chordoma-app-19rjyr.streamlitapp.com/ .

CONCLUSION

ML algorithms based on time-to-event results are effective in chordoma prediction, with DeepSurv having the best discrimination performance and calibration.

Management strategies in clival and craniovertebral junction chordomas: a 29-year experience

OBJECTIVE

Chordomas represent one of the most challenging subsets of skull base and craniovertebral junction (CVJ) tumors to treat. Despite extensive resection followed by proton-beam radiation therapy, the recurrence rate remains high, highlighting the importance of developing efficient treatment strategies. In this study, the authors present their experience in treating clival and CVJ chordomas over a 29-year period.

METHODS

The authors conducted a retrospective study of clival and CVJ chordomas that were surgically treated at their institution from 1991 to 2020. This study focuses on three aspects of the management of these tumors: the factors influencing the extent of resection (EOR), the predictors of survival, and the outcomes of the endoscopic endonasal approaches (EEAs) compared with open approaches (OAs).

RESULTS

A total of 265 surgical procedures were performed in 210 patients, including 123 OAs (46.4%) and 142 EEAs (53.6%). Tumors that had an intradural extension (p = 0.03), brainstem contact (p = 0.005), cavernous sinus extension (p = 0.004), major artery encasement (p = 0.01), petrous apex extension (p = 0.003), or high volume (p = 0.0003) were significantly associated with a lower EOR. The 5-year progression-free survival (PFS) and overall survival (OS) rates were 52.1% and 75.1%, respectively. Gross-total resection and Ki-67 labeling index < 6% were considered to be independent prognostic factors of longer PFS (p = 0.0005 and p = 0.003, respectively) and OS (p = 0.02 and p = 0.03, respectively). Postoperative radiation therapy correlated independently with a longer PFS (p = 0.006). Previous surgical treatment was associated with a lower EOR (p = 0.01) and a higher rate of CSF leakage after EEAs (p = 0.02) but did not have significantly lower PFS and OS compared with primary surgery. Previously radiation therapy correlated with a worse outcome, with lower PFS and OS (p = 0.001 and p = 0.007, respectively). EEAs were more frequently used in patients with upper and middle clival tumors (p = 0.002 and p < 0.0001, respectively), had a better rate of EOR (p = 0.003), and had a lower risk of de novo neurological deficit (p < 0.0001) compared with OAs. The overall rate of postoperative CSF leakage after EEAs was 14.8%.

CONCLUSIONS

This large study showed that gross-total resection should be attempted in a multidisciplinary skull base center before providing radiation therapy. EEAs should be considered as the gold-standard approach for upper/middle clival lesions based on the satisfactory surgical outcome, but OAs remain important tools for large complex chordomas.

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.

The transnasal endoscopic approach for resection of clival tumors: a single-center experience

Clival tumors present challenging entities regarding their treatment options. Due to their proximity to critical neurovascular structures, the operative goal of gross total tumor resection is rendered more difficult by a high risk of neurological deficits. Retrospective cohort study of patients treated for clival neoplasms through a transnasal endoscopic approach between 2009 and 2020. Assessment of preoperative clinical status, length of operation, number of approaches, pre- and postoperative radiotherapy, and the clinical outcome. Presentation and clinical correlation with our new classification. In total, 59 transnasal endoscopic operations were performed on 42 patients over 12 years. Most lesions were clival chordomas; 63% of the lesions did not reach the brainstem. Cranial nerve impairment was present in 67% of the patients, and 75% of the patients with cranial nerve palsy improved after surgical treatment. Interrater reliability for our proposed tumor extension classification showed a substantial agreement (Cohen's κ = 0.766). The transnasal approach was sufficient to achieve a complete tumor resection in 74% of the patients. Clival tumors exhibit heterogeneous characteristics. Depending on clival tumor extension, the transnasal endoscopic approach can present a safe surgical technique for upper and middle clival tumor resection, with a low risk of perioperative complications and a high rate of postoperative improvement.

Development and validation of a preoperative MRI-based radiomics nomogram to predict progression-free survival in patients with clival chordomas

Objectives

The aim of this study was to establish and validate a MRI-based radiomics nomogram to predict progression-free survival (PFS) of clival chordoma.

Methods

A total of 174 patients were enrolled in the study (train cohort: 121 cases, test cohort: 53 cases). Radiomic features were extracted from multiparametric MRIs. Intraclass correlation coefficient analysis and a Lasso and Elastic-Net regularized generalized linear model were used for feature selection. Then, a nomogram was established via univariate and multivariate Cox regression analysis in the train cohort. The performance of this nomogram was assessed by area under curve (AUC) and calibration curve.

Results

A total of 3318 radiomic features were extracted from each patient, of which 2563 radiomic features were stable features. After feature selection, seven radiomic features were selected. Cox regression analysis revealed that 2 clinical factors (degree of resection, and presence or absence of primary chordoma) and 4 radiomic features were independent prognostic factors. The AUC of the established nomogram was 0.747, 0.807, and 0.904 for PFS prediction at 1, 3, and 5 years in the train cohort, respectively, compared with 0.582, 0.852, and 0.914 in the test cohort. Calibration and risk score stratified survival curves were satisfactory in the train and test cohort.

Conclusions

The presented nomogram demonstrated a favorable predictive accuracy of PFS, which provided a novel tool to predict prognosis and risk stratification. Our results suggest that radiomic analysis can effectively help neurosurgeons perform individualized evaluations of patients with clival chordomas.

Skull Base Registries: A Roadmap

Hospitals, payors, and patients increasingly expect us to report our outcomes in more detail and to justify our treatment decisions and costs. Although there are many stakeholders in surgical outcomes, physicians must take the lead role in defining how outcomes are assessed. Skull base lesions interact with surrounding anatomy to produce a complex spectrum of presentations and surgical challenges, requiring a wide variety of surgical approaches. Moreover, many skull base lesions are relatively rare. These factors and others often preclude the use of prospective randomized clinical trials, thus necessitating alternate methods of scientific inquiry. In this paper, we propose a roadmap for implementing a skull base registry, along with expected benefits and challenges.

High systemic inflammation score is associated with adverse survival in skull base chordoma

Background

The systemic inflammation score (SIS), based on preoperative lymphocyte to monocyte ratio (LMR) and albumin (ALB), was recently developed and is demonstrated to be a novel prognostic indicator in several cancers. However, data discussing the utility of SIS in chordoma are lacking. We aimed to investigate the distribution and the prognostic role of SIS in primary skull base chordoma patients undergoing surgery.

Material and methods

Preoperative SIS was retrospectively collected from 183 skull base chordoma patients between 2008 and 2014 in a single center. Its associations with clinical features and overall survival (OS) were further analyzed. The SIS-based nomogram was developed and evaluated by the concordance index (C-index), time-dependent receiver operating characteristic (ROC) curve, calibration curve, and decision curve analysis (DCA).

Results

The numbers of patients in the SIS 2, 1, and 0 group were 29 (15.8%), 60 (32.8%), 94 (51.4%), respectively. High SIS was associated with older age (p = 0.008), brainstem involvement of tumors (p = 0.039), and adverse OS (p < 0.001). Importantly, multivariate Cox analysis showed that high SIS independently predicts adverse OS. Furthermore, the nomogram based on SIS and clinical variables showed eligible performance for OS prediction in both training and validation cohorts.

Conclusions

The SIS is a promising, simple prognostic biomarker, and the SIS-based nomogram serves as a potential risk stratification tool for outcome in skull base chordoma patients.

Clinical Grading System, Surgical Outcomes and Prognostic Analysis of Cranial Base Chordomas

Objective

Cranial base chordomas are rare, but their treatment is challenging. Tumor recurrence is still common despite improvements in microsurgical techniques and postoperative radiotherapy. We retrospectively analyzed the course of treatment, overall survival, and recurrence/progression of chordomas over the past 10 years.

Methods

We retrospectively reviewed 50 patients who underwent surgery at Tianjin Huanhu Hospital between 2010 and 2020 and were pathologically diagnosed with chordomas. Tumor resection was performed within the maximum safe range in all patients; the extent of resection was evaluated by imaging; and the incidence of complications, recurrence or progression, and overall survival were assessed.

Results

Fifty patients were divided into the low-risk group (LRG) and high-risk group (HRG) based on the cranial chordoma grading system (CCGS). The Karnofsky Performance Scale scores and gross total resection rate of the LRG were significantly higher than those of the HRG (p<0.05). The incidence of complications and mortality in the LRG were lower than those of HRG. The analysis of cumulative survival and cumulative recurrence free survival/progression free survival (RFS/PFS) showed no statistical differences in the extent of resection for survival, recurrence, or progression. Univariate and multivariate analyses showed that Ki-67 was significantly associated with tumor recurrence and was an independent hazard factor (p=0.02).

Conclusion

The CCGS can help neurosurgeons anticipate surgical outcomes. Pathological results are important in evaluating the possibility of tumor recurrence, and postoperative radiotherapy improves overall survival and RFS/PFS.

Multivariate Analysis and Validation of the Prognostic Factors for Skull Base Chordoma

Background: Skull base chordoma is a rare tumor with low-grade malignancy and a high recurrence rate, the factors affecting the prognosis of patients need to be further studied. For that, we investigated prognostic factors of skull base chordoma through the database of the Surveillance, Epidemiology, and End Results (SEER) program, and validated in an independent data set from the Xiangya Hospital.

Methods: Six hundred and forty-three patients diagnosed with skull base chordoma were obtained from the SEER database (606 patients) and the Xiangya Hospital (37 patients). Categorical variables were selected by Chi-square test with a statistical difference. Survival curves were constructed by Kaplan–Meier analysis and compared by log-rank test. Univariate and multivariate Cox regression analyses were used to explore the prognostic factors. Propensity score matching (PSM) analysis was undertaken to reduce the substantial bias between gross total resection (GTR) and subtotal resection (STR) groups. Furthermore, clinical data of 37 patients from the Xiangya Hospital were used as validation cohorts to check the survival impacts of the extent of resection and adjuvant radiotherapy on prognosis.

Results: We found that age at diagnosis, primary site, disease stage, surgical treatment, and tumor size was significantly associated with the prognosis of skull base chordoma. PSM analysis revealed that there was no significant difference in the OS between GTR and STR (p = 0.157). Independent data set from the Xiangya Hospital proved no statistical difference in OS between GTR and STR groups (p = 0.16), but the GTR group was superior to the STR group for progression-free survival (PFS) (p = 0.048). Postoperative radiotherapy does not improve OS (p = 0.28), but it can prolong PFS (p = 0.0037). Nomograms predicting 5- and 10-year OS and DSS were constructed based on statistically significant factors identified by multivariate Cox analysis. Age, primary site, tumor size, surgical treatment, and disease stage were included as prognostic predictors in the nomograms with good performance.

Conclusions: We identified age, tumor size, surgery, primary site, and tumor stage as main factors affecting the prognosis of the skull base chordoma. Resection of the tumor as much as possible while ensuring safety, combined with postoperative radiotherapy may be the optimum treatment for skull base chordoma.

Endoscopic Endonasal Surgical Strategy for Skull Base Chordomas Based on Tumor Growth Directions: Surgical Outcomes of 167 Patients During 3 Years

Background

Skull base chordomas (SBCs) are rare malignant bone tumors with dismal long-term local control. Endoscopic endonasal surgeries (EESs) are increasingly adopted to resect SBCs recently. Gross total resection (GTR) favors good outcomes. However, the SBCs often invade the skull base extensively and hide behind vital neurovascular structures; the tumors were challenging to remove entirely. To improve the GTR, we established a surgical strategy for EES according to the tumor growth directions.

Methods

A total of 112 patients with SBCs from 2018 to 2019 were classified into the derivation group. We retrospectively analyzed their radiologic images and operation videos to find the accurate tumor locations. By doing so, we confirmed the tumor growth directions and established a surgical strategy. Fifty-five patients who were operated on in 2020 were regarded as the validation group, and we performed their operations following the surgical strategy to verify its value.

Results

In the derivation group, 78.6% of SBCs invade the dorsum sellae and posterior clinoid process region. 62.5% and 69.6% of tumors extend to the left and right posterior spaces of cavernous ICA, respectively. 59.8% and 61.6% of tumors extend to the left and right posterior spaces of paraclival and lacerum ICA (pc-la ICA), respectively. 30.4% and 28.6% of tumors extended along the left and right petroclival fissures that extend toward the jugular foramen, respectively. 30.4% of tumors involved the foramen magnum and craniocervical junction region. The GTR was achieved in 60.8% of patients with primary SBCs in the derivation group. Based on the tumors’ growth pattern, pituitary transposition and posterior clinoidectomy techniques were adopted to resect tumors that hid behind cavernous ICA. Paraclival ICA transposition was used when the tumor invaded the posterior spaces of pc-la ICA. Lacerum fibrocartilage resection and eustachian tube transposition may be warranted to resect the tumors that extended to the jugular foramen. GTR was achieved in 75.0% of patients with primary SBCs in the validation group.

Conclusion

Besides the midline clival region, the SBCs frequently grow into the eight spaces mentioned above. The surgical strategy based on the growth pattern contributes to increasing the GTR rate.

Mid-term follow-up surgical results in 284 cases of clival chordomas: the risk factors for outcome and tumor recurrence

Objective

Skull base chordoma (SBC) is rare and one of the most challenging diseases to treat. We aimed to assess the optimal timing of adjuvant radiation therapy (RT) and to evaluate the factors that influence resection and long-term outcomes.

Methods

In total, 284 patients with 382 surgeries were enrolled in this retrospective study. Postsurgically, 64 patients underwent RT before recurrence (pre-recurrence RT), and 47 patients underwent RT after recurrence. During the first attempt to achieve gross-total resection (GTR), when the entire tumor was resected, 268 patients were treated with an endoscopic midline approach, and 16 patients were treated with microscopic lateral approaches. Factors associated with the success of GTR were identified using χ² and logistic regression analyses. Risk factors associated with chordoma-specific survival (CSS) and progression-free survival (PFS) were evaluated with the Cox proportional hazards model.

Results

In total, 74.6% of tumors were marginally resected [GTR (40.1%), near-total resection (34.5%)]. History of surgery, large tumor volumes, and tumor locations in the lower clivus were associated with a lower GTR rate. The mean follow-up period was 43.9 months. At the last follow-up, 181 (63.7%) patients were alive. RT history, histologic subtype (dedifferentiated and sarcomatoid), non-GTR, no postsurgical RT, and the presence of metastasis were associated with poorer CSS. Patients with pre-recurrence RT had the longest PFS and CSS, while patients without postsurgical RT had the worst outcome.

Conclusion

GTR is the goal of initial surgical treatment. Pre-recurrence RT would improve outcome regardless of GTR.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10143-021-01576-4.

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.

Tumor Growth Rate as a New Predictor of Progression-Free Survival After Chordoma Surgery

BACKGROUND

Currently, different postoperative predictors of chordoma recurrence have been identified. Tumor growth rate (TGR) is an image-based calculation that provides quantitative information of tumor's volume changing over time and has been shown to predict progression-free survival (PFS) in other tumor types.

OBJECTIVE

To explore the usefulness of TGR as a new preoperative radiological marker for chordoma recurrence.

METHODS

A retrospective single-institution study was carried out including patients reflecting these criteria: confirmed diagnosis of chordoma on pathological analysis, no history of previous radiation, and at least 2 preoperative thin-slice magnetic resonance images available to measure TGR. TGR was calculated for all patients, showing the percentage change in tumor size over 1 mo.

RESULTS

A total of 32 patients were retained for analysis. Patients with a TGR ≥ 10.12%/m had a statistically significantly lower mean PFS (P < .0001). TGR ≥ 10.12%/m (odds ratio = 26, P = .001) was observed more frequently in recurrent chordoma. In a subgroup analysis, we found that the association of Ki-67 labeling index ≥ 6% and TGR ≥ 10.12%/m was correlated with recurrence (P = .0008).

CONCLUSION

TGR may be considered as a preoperative radiological indicator of tumor proliferation and seems to preoperatively identify more aggressive tumors with a higher tendency to recur. Our findings suggest that the therapeutic strategy and clinical-radiological follow-up of patients with chordoma can be adapted also according to this new parameter.

Surgical Management of Skull Base and Spine Chordomas

OPINION STATEMENT

Management of chordoma along the cranial-spinal axis is a major challenge for both skull base and spinal surgeons. Although chordoma remains a rare tumor, occurring in approximately 1 per 1 million individuals, its treatment poses several challenges. These tumors are generally poorly responsive to radiation and chemotherapy, leading to surgical resection as the mainstay of treatment. Due to anatomic constraints and unique challenges associated with each primary site of disease, gross total resection is often not feasible and is associated with high rates of morbidity. Additionally, chordoma is associated with high rates of recurrence due to the tumor's aggressive biologic features, and postoperative radiation is increasingly incorporated as a treatment option for these patients. Despite these challenges, modern-day surgical techniques in both skull base and spinal surgery have facilitated improved patient outcomes. For example, endoscopic endonasal techniques have become the mainstay in resection of skull base chordomas, improving the ability to achieve gross total resection, while reducing associated morbidity of open transfacial techniques. Resection of spinal chordomas has been facilitated by emerging techniques in preoperative imaging, intraoperative navigation, spinal reconstruction, and radiotherapy. Taken collectively, the treatment of chordoma affecting the skull base and spinal requires a multidisciplinary team of surgeons, radiation oncologists, and medical oncologists who specialize in the treatment of this challenging disease.

Apparent diffusion coefficient as a prognostic factor in clival chordoma

Clival chordoma is a rare disease with high recurrence rates even after a combination of surgical resection and radiotherapy. Apparent diffusion coefficient (ADC) has been used to evaluate aggressive features of chordoma, but its utility for clival chordoma has not been explored specifically. In this study, the utility of preoperative ADC values was analyzed for predicting tumor progression and recurrence in patients with clival chordoma. Between 2012 and 2019, a total of 30 operated cases were analyzed with available preoperative ADC data. Receiver operating characteristic (ROC) analysis was used to obtain ADC cutoff values for predicting tumor aggressiveness. The mean and minimum ADC values were significantly lower in the aggressive tumor group than in the stable tumor group (both P < 0.001). ROC analysis showed that a mean cutoff ADC value of 1198 × 10⁻⁶ mm²/s and minimum ADC value of 895.5 × 10^–6 mm²/s could be used to predict aggressive features of clival chordoma. Subtotal resection, partial resection, and mean and minimum ADC values that were lower than cutoff values were negative predictors of overall survival and progression-free survival. In conclusion, mean and minimum ADC values could be useful in predicting aggressiveness of clival chordoma.

Vertebrobasilar Artery Encasement by Skull Base Chordomas: Surgical Outcome and Management Strategies

BACKGROUND

Vascular encasement by skull base chordomas can increase surgical risk and hinder completeness of resection. However, the evidence behind this remains anecdotic.

OBJECTIVE

To give a better portrayal of chordomas encasing vertebrobasilar arteries mainly in regard of surgical vascular risk and its impact on extent of resection.

METHODS

A retrospective cohort study comparing skull base chordomas with encasement (≥180o encirclement) of the vertebrobasilar arteries to a control group of skull base chordomas with intradural extension. Data gathered involved pre- and postoperative volumetric analysis of the tumor, degree of encasement of involved vessel, occurrence of complication, and survival data including progression-free survival (PFS) and overall survival (OS).

RESULTS

A total of 24 patients with vertebrobasilar encasement were included in the study and an equal number of control cases were randomly selected from the same time period, totalizing 48 patients. Lower clival tumors with condyle involvement were more likely to have encasement. Gross total resection (GTR) rate was significantly lower in the encasement group (13% vs 42%, P = .023). Rates of postoperative new neurological deficit, CFS leak and 30 d postoperative mortality were not statistically different between groups. There was no statistically significant difference in mean PFS (P = .608) and OS (P = .958).

CONCLUSION

Skull base chordomas encasing vertebrobasilar arteries are highly challenging tumors. This study demonstrates that although safe resection is possible, GTR is hindered by the presence of encasement. We advocate letting the tumor's adherence to vessels lead the resection, leaving a small piece of tumor behind if adherent to the vessels.

Stent-Assisted Coil Embolization of a Basilar Artery Dissecting Aneurysm Involved in Skull Base Chordoma Before Endoscopic Transsphenoidal Transclival Resection

BACKGROUND

Skull base chordomas will occasionally penetrate the clival dura mater and extend into the prepontine cistern, involving the basilar artery. Few reports have described cases of skull base chordoma accompanying a dissecting aneurysm of the basilar artery, and the treatment strategies have remained largely unknown.

CASE DESCRIPTION

A 28-year-old man was referred to our hospital with a complaint of severe headache. A skull base chordoma involving a basilar artery dissecting aneurysm was diagnosed. We initially performed endovascular surgery for the dissecting aneurysm after dual antiplatelet therapy before surgical resection of the tumor, which was successfully achieved without complications. Follow-up angiography 3 months after endovascular surgery disclosed obliteration of the dissecting aneurysm. We then stopped the dual antiplatelet therapy, and performed judicious resection using an endoscopic transclival approach. The residual tumor was treated with radiosurgery. At the last follow-up examination, the patient was stable, and the tumor remained sufficiently controlled.

CONCLUSIONS

We have reported a case of a dissecting aneurysm of the basilar artery with clival chordoma. Our findings suggest that chordoma with intradural vascular encasement has the potential to invade the vessel wall. To avoid rupture of those critical vascular structures, treatment strategies that minimize stress on the involved arteries and offer safe and sufficient surgical resection should be considered.

Use of Salvage Surgery or Stereotactic Radiosurgery for Multiply Recurrent Skull Base Chordomas: A Single-Institution Experience and Review of the Literature

Introduction  Chordomas are locally destructive neoplasms characterized by appreciable recurrence rates after initial multimodality treatment. We examined the outcome of salvage treatment in recurrent/progressive skull base chordomas. Methods  This is a retrospective review of recurrent/progressive skull base chordomas at a tertiary urban academic medical center. The outcomes evaluated were overall survival, progression-free survival (PFS), and incidence of new toxicity. Results  Eighteen consecutive patients who underwent ≥1 course of treatment (35.3% salvage surgery, 23.5% salvage radiation, and 41.2% both) were included. The median follow-up was 98.6 months (range 16-215 months). After initial treatment, the median PFS was 17.7 months (95% confidence interval [CI]: 4.9-22.6 months). Following initial therapy, age ≥ 40 had improved PFS on univariate analysis ( p  = 0.03). All patients had local recurrence, with 15 undergoing salvage surgical resections and 16 undergoing salvage radiation treatments (mostly stereotactic radiosurgery [SRS]). The median PFS was 59.2 months (95% CI: 4.0-99.3 months) after salvage surgery, 58.4 months (95% CI: 25.9-195 months) after salvage radiation, and 58.4 months (95% CI: 25.9.0-98.4 months) combined. Overall survival for the total cohort was 98.7% ± 1.7% at 2 years and 92.8% ± 5.5% at 5 years. Salvage treatments were well-tolerated with two patients (11%) reporting tinnitus and one patient each (6%) reporting headaches, visual field deficits, hearing loss, anosmia, dysphagia, or memory loss. Conclusion  Refractory skull base chordomas present a challenging treatment dilemma. Repeat surgical resection or SRS seems to provide adequate salvage therapy that is well-tolerated when treated at a tertiary center offering multimodality care.

Natural Growth Dynamics of Untreated Skull Base Chordomas In Vivo

OBJECTIVE

To study the natural growth dynamics of skull base chordomas.

METHODS

A retrospective study of skull base chordomas was performed. Patients with ≥2 preoperative magnetic resonance (MR) images and with pathologically confirmed chordomas were enrolled. All clinical data and MR images were studied.

RESULTS

Twenty-one patients with pathologically confirmed skull base chordomas were enrolled. The mean volume of the tumors at diagnosis was 19.9 ± 17.0 cm³, with a mean interval examination period of 22.4 ± 26.1 (range, 3-113) months. The mean tumor volume change was approximately 15.4 ± 16.3 cm³. The mean specific growth rate was 8% ± 9% per month, and the mean specific growth volume was 0.8 ± 0.7 cm³ per month. The tumor MR signal index grade, female gender, no dura mater breakthrough, endophytic type, small tumors, and soft tumor texture were related to a higher tumor growth rate (P < 0.05), and small tumors showed the greatest growth rate compared with the middle-sized and large tumors. Curve estimation was performed using a power function (R² = 0.545).

CONCLUSIONS

The skull base chordoma is a slow-growing tumor. The cases involving characteristics of female gender, endophytic type, small tumor size, and MR grade 3 showed a higher growth rate.

Identification of the Different Roles and Potential Mechanisms of T Isoforms in the Tumor Recurrence and Cell Cycle of Chordomas

Purpose

The roles of T (brachyury) isoforms in chordomas remain unclear. This study aimed to investigate the different roles and mechanisms of them in chordomas.

Patients and methods

The expression of T isoforms mRNAs in 57 chordomas was assessed, and a prognosis analysis was conducted. Cell apoptosis, proliferation and cell cycle assays were performed after specific T isoform mRNA knockdown. Whole-transcriptome sequencing, Gene Set Enrichment Analysis, Gene Ontology analysis, Kyoto Encyclopedia of Genes and Genomes analysis and competing endogenous RNA (ceRNA) analysis were conducted.

Results

As revealed in this study, the T-long isoform was a significant risk factor (hazard ratio [HR], 1.09; P=0.018) and the T-short isoform was a protective factor (HR, 0.24; P=0.012) associated with tumor recurrence. After T-long isoform knockdown, the cell cycle was arrested at G0/G1 phase and cell proliferation was significantly inhibited. A bioinformatic analysis revealed that the upregulation of H19, P21 and GADD45B; downregulation of SKP2 and CDK2; and accompanying changes in the P53 signaling pathway consistently contributed to G0/G1 arrest. After T-short isoform knockdown, the cell cycle was arrested at G2/M phase and cell apoptosis tended to increase slightly (P=0.067). The upregulation of YWHAZ and downregulation of E2F1 and its target genes might contribute to cell cycle arrest in G2/M phase and apoptosis. In addition, the ceRNA network, consisting of long noncoding RNAs, mRNAs and microRNAs, was established.

Conclusion

The T-long isoform was a risk factor and the T-short isoform was a protective factor for chordoma recurrence. In addition, the cell cycle was the main target of T isoforms knockdown, and the changes in the downstream transcriptome may contribute to the different effects of specific T isoform knockdown on the changes in the cell cycle distributions and apoptosis and proliferation of chordoma cells.

Lessons learned in the evolution of endoscopic skull base surgery

OBJECTIVEEndoscopic skull base surgery (ESBS) is a relatively recent addition to the neurosurgical armamentarium. As with many new approaches, there has been significant controversy regarding its value compared with more traditional approaches to ventral skull base pathology. Although early enthusiasm for new approaches that appear less invasive is usually high, these new techniques require rigorous study to ensure that widespread implementation is in the best interest of patients.METHODSThe authors compared surgical results for ESBS with transcranial surgery (TCS) for several different pathologies over two different time periods (prior to 2012 and 2012-2017) to see how results have evolved over time. Pathologies examined were craniopharyngioma, anterior skull base meningioma, esthesioneuroblastoma, chordoma, and chondrosarcoma.RESULTSESBS offers clear advantages over TCS for most craniopharyngiomas and chordomas. For well-selected cases of planum sphenoidale and tuberculum sellae meningiomas, ESBS has similar rates of resection with higher rates of visual improvement, and more recent results with lower CSF leaks make the complication rates similar between the two approaches. TCS offers a higher rate of resection with fewer complications for olfactory groove meningiomas. ESBS is preferred for lower-grade esthesioneuroblastomas, but higher-grade tumors often still require a craniofacial approach. There are few data on chondrosarcomas, but early results show that ESBS appears to offer clear advantages for minimizing morbidity with similar rates of resection, as long as surgeons are familiar with more complex inferolateral approaches.CONCLUSIONSESBS is maturing into a well-established approach that is clearly in the patients' best interest when applied by experienced surgeons for appropriate pathology. Ongoing critical reevaluation of outcomes is essential for ensuring optimal results.

Endoscopic transnasal surgery of clival lesions: our experience

BACKGROUND

The clivus is a region characterized by complex anatomy, with vascular and neural structures that are located in close proximity. Different pathologies can affect this area, and traditional surgical approaches were open approaches. Recently, the endoscopic transnasal technique has been introduced, and currently represents a good alternative for the surgical management of these lesions. This is a preliminary report on patients treated endoscopically for clival lesions by the authors' Skull Base Team.

PATIENTS AND METHODS

This was a retrospective chart review of patients who underwent an endoscopic exclusive transnasal approach (EEA) or a transoral one (TO) for clival lesions between June 2015 and November 2017 at our Skull Base Referral Center. Patient characteristics and symptoms, preoperative neuroradiological evaluation, surgical approach, complications, and postoperative results were evaluated.

RESULTS

Nine patients (6 females and 3 males; age range 6-82 years, mean 50.8 years) underwent EEA or TO. From histological analysis, we found chordomas (6/9 subjects), chondrosarcoma (1/9), craniopharyngioma (1/9), and eosinophilic granuloma (1/9). Three patients had previously been operated for a parasellar chondrosarcoma (1/9), a pituitary macroadenoma (1/9), or a chondroid chordoma (1/9). The lesions were totally (2/9) or sub-totally (5/9) resected, debulked (1/9), or analyzed with a biopsy (1/9). Reconstruction was accomplished with a multilayer technique (7/9), or with a gasket-seal (1/9), using a mucoperichondrial graft, a single/double nasoseptal flap, a middle turbinate flap, a fascia lata, or a synthetic fascia. One patient (11.1%) was re-operated on due to cerebrospinal leakage, without further complications. Two patients (22.2%) were re-operated on due to chordoma regrowth. Adjuvant chemotherapy was administered to 1/9 patient with progressive healing. All of the other patients underwent proton-beam radiotherapy with no documented tumor growth (median follow-up: 20 months; range 5.1-29.9 months).

CONCLUSIONS

Clival lesions represent a heterogeneous group of lesions located in a very complex and difficult area. EEA and TO approaches are safe and mini-invasive, with lower morbidity and with postoperative complications when compared to the traditional open approaches, according to the extent and type of pathology.