Surgical treatment of sacral chordoma: survival and prognostic factors

Nomograms to predict lung metastasis in malignant primary osseous spinal neoplasms and cancer-specific survival in lung metastasis subgroup

Purpose

To construct and validate nomograms for predicting lung metastasis probability in patients with malignant primary osseous spinal neoplasms (MPOSN) at initial diagnosis and predicting cancer-specific survival (CSS) in the lung metastasis subgroup.

Methods

A total of 1,298 patients with spinal primary osteosarcoma, chondrosarcoma, Ewing sarcoma, and chordoma were retrospectively collected. Least absolute shrinkage and selection operator (LASSO) and multivariate logistic analysis were used to identify the predictors for lung metastasis. LASSO and multivariate Cox analysis were used to identify the prognostic factors for 3- and 5-year CSS in the lung metastasis subgroup. Receiver operating characteristic (ROC) curves, calibration curves, and decision curve analyses (DCA) were used to estimate the accuracy and net benefits of nomograms.

Results

Histologic type, grade, lymph node involvement, tumor size, tumor extension, and other site metastasis were identified as predictors for lung metastasis. The area under the curve (AUC) for the training and validating cohorts were 0.825 and 0.827, respectively. Age, histologic type, surgery at primary site, and grade were identified as the prognostic factors for the CSS. The AUC for the 3- and 5-year CSS were 0.790 and 0.740, respectively. Calibration curves revealed good agreements, and the Hosmer and Lemeshow test identified the models to be well fitted. DCA curves demonstrated that nomograms were clinically useful.

Conclusion

The nomograms constructed and validated by us could provide clinicians with a rapid and user-friendly tool to predict lung metastasis probability in patients with MPOSN at initial diagnosis and make a personalized CSS evaluation for the lung metastasis subgroup.

Management of Chordoma of the Sacrum and Mobile Spine

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Chordomas account for 1% to 4% of primary tumors of the spine and sacrum.

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En bloc resection is the preferred surgical treatment for the management of chordomas.

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Proton beam radiation is increasingly being used as a postoperative radiation modality for the treatment of chordomas.

Nomograms for predicting long-term overall survival and cancer-specific survival in chordoma: a population-based study

Background: The aim of this study was to develop two predictive models to predict overall survival (OS) and cancer-specific survival (CSS) in chordoma patients. Methods: We searched for independent prognostic factors by using univariate and multivariate Cox regression analyses. The prediction model of OS and CSS of chordoma patients was constructed by using the screened factors. Results: The study enrolled 362 chordoma patients. Cox regression analysis showed that disease stage, age, surgery, marital status and tumor size are independent influencing factors of OS and CSS in chordoma patients. After testing, the prediction model constructed in this study has good performance. Conclusion: Two predictive models were successfully constructed and validated for chordoma patients' OS and CSS.

LncRNA NONHSAT114552 Sponges miR-320d to Promote Proliferation and Invasion of Chordoma Through Upregulating NRP1

Chordoma is a relatively rare malignant bone tumor with high local recurrence. To date, the mechanism remains unclear. lncRNAs play a pivotal role in tumorigenesis by acting as competitive endogenous RNAs of microRNAs. However, the biological role of lncRNA is still unclear in chordoma. In this research, our aim is to investigate the roles and regulation mechanisms of lncRNA NONHSAT114552 in chordoma development. The expression level of NONHSAT114552 and miR-320d in chordoma tissues was determined by qRT-PCR. Meantime, the correlation between NONHSAT114552 and clinical prognosis was also studied. Bioinformatics analysis and luciferase reporter assays were used to verify the relationship between NONHSAT114552 and miR-320d, and between miR-320d and Neuropilin 1 (NRP1). In addition, effects of NONHSAT114552 on chordoma cells (U-CH1 and U-CH2) proliferation and invasion and its regulation on miR-320d were also evaluated. Furthermore, the influences of NONHSAT114552/miR-320d/NRP1 axis on chordoma tumorigenesis were investigated in vivo. NONHSAT114552 was overexpressed while miR-320d was down-regulated in chordoma tissue compared to fetal nucleus pulposus. Kaplan-Meier survival analysis showed that NONHSAT114552 overexpression was associated with patients’ poor prognosis. Knockdown of NONHSAT114552 significantly suppressed chordoma cell proliferation and invasion. In vitro studies confirmed that NONHSAT114552 acted as ceRNA to regulate NRP1 by directly sponging miR-320d, thus facilitating chordoma cell proliferation and invasion. In vivo study demonstrated that NONHSAT114552 moderated chordoma growth by sponging miR-320d to regulating NRP1. Our findings indicate that lncRNA NONHSAT114552 exhibits a critical role in the tumorigenesis and development of chordoma and it may become one potential prognostic marker and therapeutic target for this disease. .

Surgical Management of Spinal Chordoma: A Systematic Review and Single-Center Experience

OBJECTIVE

Chordoma is a rare neoplasm of the neuraxis derived from remnants of the primitive notochord. The importance of wide margins and use of adjuvant therapy in spinal chordomas are still contentious points in the management of spinal chordomas. We conducted a systematic review of the surgical management of spinal chordomas alongside our 10-year institutional experience.

METHODS

A systematic search of the literature was performed in November 2020 using Embase and MEDLINE for articles regarding the surgical management of chordomas arising from the mobile spine and sacrum. We also searched for all adult patients who were surgically managed for spinal chordomas at our institute between 2010 and 2020. In both the systematic review and our institutional case series, data on adequacy of resection, use of adjuvant therapy, complications, recurrence (local or metastatic), and survival outcomes were collected.

RESULTS

We identified and analyzed 42 articles, yielding 1531 patients, from which the overall gross total or wide resection rate was 54.9%. Among the 8 cases in our institutional experience (4 sacral, 3 cervical, and 1 lumbar), we achieved gross total resection in 50% of initial operations. The recurrence rate was 25% in our gross total resection group and 50% where initial resection was subtotal. Of patients, 75% had no evidence of recurrence at most recent follow-up.

CONCLUSIONS

Albeit difficult at times because of the proximity to neurovascular tissue, achieving a wide resection followed by adjuvant therapy for spinal chordomas is of great importance. Multidisciplinary discussion is valuable to ensure the best outcome for the patient.

Outcomes of Surgery for Sacral Chordoma and Impact of Complications: A Report of 50 Consecutive Patients With Long-Term Follow-Up

STUDY DESIGN

Retrospective case series.

OBJECTIVE

To determine predictive factors of overall survival (OS) and local recurrence (LR), report complications, and assess the impact of complications on survival, recurrence, and function in patients undergoing en bloc resection of sacral chordoma.

METHODS

This retrospective case series was obtained from a prospective database (1995-2016). All patients underwent en bloc resection of sacral chordoma. Demographic, perioperative, and complication data were collected. Outcomes included: overall survival(OS), local recurrence(LR), and complications. Survival analysis with multivariable cox regression was performed.

RESULTS

Among 50 patients, median follow-up was 5.3 years (range = 1.3-17.2). The majority (82%) underwent a negative margin resection. Survival: 17 patients died (34%) with a median OS of 10.0 years (range = 1.3-17.2). Multivariable cox regression revealed that a negative margin resection was not significantly associated with improved survival (HR = 3.35, 95%CI 0.87-12.80, P = .078). Recurrence: 20 patients (40%) experienced LR with a median time of 6.2 years (range = 0-16.9). Multivariable cox regression revealed that a negative margin resection was associated with a significant decreased risk of LR (HR = 4.96, 95%CI 1.84-13.34, P = 0.002,). A 62% overall complication rate was seen (42% major), with 26% reoperation rate. Of the reoperations, 54% were delayed (>6 weeks after the index surgery). Multivariable cox regression demonstrated that neither major complication nor reoperation significantly impacted OS (HR = 0.62, 95%CI 0.22-1.79, P = 0.380), LR (HR = 1.28, 95%CI 0.49-3.36, P = 0.611), or functional outcomes (OR = 2.94, 95%CI 0.25-34.8, P = 0.393).

CONCLUSIONS

Negative margin resection was associated with decreased LR. Neither major complication nor reoperation significantly impacted OS, LR, or functional outcome. Though additional studies are needed, it appears that despite the morbidity associated with sacral chordoma resection, the long-term clinical outcomes are favorable.

Cervical chordomas: multicenter case series and meta-analysis

BACKGROUND

En bloc spondylectomy is the gold standard for surgical resection of sacral chordomas (CHO), but the effect of extent of resection on recurrence and survival in patients with CHO of the cervical spine remains elusive.

METHODS

MEDLINE, Embase, Scopus, and Cochrane were systematically reviewed. Patients with cervical CHO treated at three tertiary-care academic institutions were reviewed for inclusion. We performed an individual participant data meta-analysis to assess the overall survival (OS) and progression free survival (PFS) after en bloc-gross total resection (GTR) and intralesional-GTR compared to subtotal resection (STR). We then performed an intention-to-treat analysis including all patients with attempted en bloc resection in the en bloc group, regardless of the surgical margins.

RESULTS

There was a total of 13 series including 161 patients with cervical CHO, including our current series of 22 patients. GTR (en bloc-GTR + intralesional-GTR) was associated with a significant decrease in the risk of local progression (pooled hazard ratio (PHR) = 0.22; 95% CI 0.08-0.59; p = 0.003) and risk of death (PHR 0.31; 95%; CI 0.12-0.83; p = 0.020). A meta-regression analyses determined that intralesional-GTR improved PFS (PHR 0.35; 95% CI 0.16-0.76; p = 0.009) as well as OS (PHR 0.25; 95% CI 0.08-0.79; p = 0.019) when compared to STR. En bloc-GTR was associated with a significant reduction in the risk of local progression (PHR 0.06; 95% CI 0.01-0.77; p = 0.030), but not a decreased OS (PHR 0.50; 95% CI 0.19-1.27; p = 0.145). Our intention-to-treat analyses revealed a near significant improvement in OS for the en bloc group (PHR: 0.15; 95% CI 0.02-1.22; p = 0.054), and nearly identical improvement in PFS. Radiation data was not available for the studies included in the meta-analysis.

CONCLUSION

This is the first and only meta-analysis of patients with cervical CHO. We found that both en bloc-GTR and intralesional-GTR resulted in improved local tumor control when compared to STR.

Nomograms to predict lung metastasis probability and lung metastasis subgroup survival in malignant bone tumors

The aim of this study was to construct and validate nomograms for predicting lung metastasis and lung metastasis subgroup overall survival in malignant primary osseous neoplasms. Least absolute shrinkage and selection operator, logistic and Cox analyses were used to identify risk factors for lung metastasis in malignant primary osseous neoplasms and prognostic factors for overall survival in the lung metastasis subgroup. Further, nomograms were established and validated. A total of 3184 patients were collected. Variables including age, histology type, American Joint Committee on Cancer T and N stage, other site metastasis, tumor extension and surgery were extracted for the nomograms. The authors found that nomograms could provide an effective approach for clinicians to identify patients with a high risk of lung metastasis in malignant primary osseous neoplasms and perform a personalized overall survival evaluation for the lung metastasis subgroup.

Surgical management of chordoma: A systematic review

Context: Chordomas are rare primary tumors of bone characterized by local aggressiveness and poor prognosis. The surgical exeresis plays a critical role for their management. Objective: The aim was to provide an overview of the surgical management of chordomas of the mobile spine and sacrum, describing the most common surgical approaches, the role of surgical margins, the difficulties of en block resection, the outcomes of surgery, the recurrence rate and the use of associated therapies. Methods: We performed a systematic search using the keywords "chordoma" in combination with "surgery", "spine", "sacrum" and "radiotherapy". Results: Fifty-eight studies, describing 1359 patients with diagnosis of chordoma were retrieved. 17 studies were performed on subjects with cervical chordomas and 49 focused on patients with sacrococcygeal chordomas. The remaining studies included patients with chordomas in cranial region and/or mobile spine and/or sacroccygeal region. The recurrence rate ranged from 25% to 60% for cervical chordomas, and from 18% to 89% for sacrococcygeal chordomas. Conclusion: Despite the remarkable advances in the local management of chordoma performed in the last decades, the current results of surgery alone are still unsatisfactory. The radical en bloc excision of tumour is technically demanding, particularly in the cervical spine. Although radical surgery must still be considered the gold standard for the management of chordomas, a multidisciplinary approach is required to improve the local control of the disease in patients who undergo both radical and non-radical surgery. Adjuvant radiation therapy increases the continuous disease-free survival and the local recurrence-free survival. Level of evidence: Systematic review; level III.

A case-control study of computer navigation assisted resection of primary sacral chordoma above sacrum 3 level

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This is a retrospective case-control study.

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The computer navigation aided technology can make more cases achieve safe surgical margin.

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The clear bone resection margins were achieved in all cases in navigation group.

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The application of computer navigation doesn’t increase the operation time and intraoperative blood loss.

Background

The operation of sacral chordoma resection is difficult especial in the tumor above sacrum 3 level and the local recurrence rate was high. The purpose of this study is to analyze the effect of computer navigation aided technology in primary sacral chordoma resection above sacrum 3 level through a case-control study, which including perioperative safety, surgical margin, postoperative recurrence and function results.

Methods

This is a retrospective case-control study. The clinical data of 25 patients received initial computer-assisted resection of sacral chordoma above the level of sacrum 3 from 2009 to 2016 were analyzed; the patients underwent non-navigation assisted resection of tumor above the level of sacrum 3 in the same period were matched and 25 patients were selected randomly. There was no significant difference between these two groups in gender (P = 0.370), age (P = 0.554), tumor transverse diameter (P = 0.836). The average maximum diameter of tumor in navigation group was significant bigger than that in non-navigation group (P = 0.005). The intraoperative safety results, surgical margin, postoperative complications, recurrence rate and function were compared between these groups.

Results

There was no significant difference between navigation and non-navigation group in operative time (P = 0.105) and intraoperative blood loss (P = 0.537). There were 18 wide resections, 4 marginal resections and 3 intracapsular resections in navigation group; there were 6 wide resections, 12 marginal resections and 7 intracapsular resections in non-navigation group; the surgical margins of two groups were significant different (P = 0.003). There were 5 cases (20%) and 6 cases (24%) with wound complication in navigation group and non-navigation group (P = 0.733). The average follow-up was 49.6 (16–102) months in navigation group and 51.3 (12–110) months in non-navigation group. Three cases (12%) showed recurrence in navigation group and six cases showed recurrence (24%) in non-navigation group. The surgical margin was significantly related with tumor recurrence (P = 0.000). The average MSTS score was 27.3 (19–30) and 26.5 (20–29) in navigation group and non-navigation group (P = 0.374).

Conclusion

The computer navigation aided technology can improve the accuracy of primary sacral chordoma resection, and make more cases achieve safe surgical margin. Compared with the traditional operation, the application of computer navigation in the larger tumor resection does not increase the operation time and intraoperative blood loss, which shows good safety.

A Combined One-Staged Robot-Assisted Sacral Chordoma Resection

BACKGROUND

The robotic surgery is an advanced modern minimally invasive technology, widely used in urologic oncology, and it has become useful in particular conditions. Over time, different surgical specialties made use of the robotic properties to minimize complications for high-risk procedures. A combined 1-staged robot-assisted multidisciplinary surgery with intraoperative neurophysiological monitoring can be a safe procedure to remove a sacral chordoma with low morbidity rates.

CASE DESCRIPTION

A 64-year-old woman complained of a few months of drug-resistant low back and abdominal pain. The subsequent development of constipation brought the patient to undergo an abdominal computed tomography scan and magnetic resonance imaging. Radiologic investigations revealed a large size sacral mass associated with a partial destruction of the sacrum and posterior compression of the rectum. The tumor was en bloc removed by a combined 1-staged anterior laparoscopic robot-assisted and posterior open lumbosacral approach with continue intraoperative neurophysiological monitoring of sacral and pudendal plexuses. The histological diagnosis was of chordoma. After surgery, the patient reported pain relief and the total recovery of bowel dysfunction with good 11-month follow-up outcome.

CONCLUSIONS

This combined technique represents a promising treatment option in selected cases. The robotic technology combined with the experience of highly qualified staff can improve the surgical result by minimizing complications. However, longer follow-up is necessary to confirm the long-term effects in terms of recurrence and survival.

Preliminary investigation of bilateral internal iliac artery ligation and anterior tumor separation through laparoscopy before posterior resection of a giant sacral tumor

BACKGROUND

Surgical is the optimal therapeutic strategy for sacral tumors, and complete resection can effectively improve the recurrence and survival rates. However, the specialized anatomy, massive bleeding and adhesion to the anterior tissue, especially that caused by giant sacral tumors, makes complete resection difficult. The laparoscopic technique provides a new method to resect sacral tumors.

METHODS

34 patients with primary giant sacral tumors who underwent surgical resection were enrolled. After bilateral internal iliac artery ligation and anterior laparoscopic tumor separation, the sacral tumors were successfully resected posteriorly. The clinical, radiological and follow-up data were collected and analyzed.

RESULTS

The average operative time was 276.47 min and that for laparoscopy was 76.24 min. The average intraoperative blood loss was 1757.64 ml. No complications associated with laparoscopic surgery, such as intestinal, urinary tract, or vascular injuries, occurred. Ten patients (29.41%) had perioperative complications, including infection, unhealed wounds, and cerebrospinal fluid leaks in 10, 5 and 2 patients, respectively. Patients with complications had significantly longer total (55.00 ± 34.53 vs 25.13 ± 14.60, P = 0.001) and postoperative (39.10 ± 30.61 vs 14.83 ± 10.00, P = 0.002) hospitalization stays than patients without complications. Postoperatively, bowel and bladder dysfunction, intestinal obstruction, pain, and perianal numbness occurred in 21, 5, 8, and 2 patients, respectively. The recurrence rate was 11.76%.

CONCLUSIONS

Laparoscopically assisted sacral tumor resection is a technically feasible and effective surgical method to resect giant sacral tumors, with the advantages of reduced operative blood loss during internal iliac artery ligation and anterior tumor separation.

Conditional survival and changing risk profile in patients with chordoma: a population-based longitudinal cohort study

Objective

To evaluate the conditional survival of patients with chordoma to potentially help physician planning of optimal cancer surveillance and guide better clinical decisions.

Methods

In total, 1942 patients with chordoma were identified and extracted from Surveillance, Epidemiology, and End Results (SEER) databases (1973–2015). The cumulative survival estimates were used to calculate the conditional survival rate, and the Greenwood formula was used to estimate the 95% CI. In addition, multivariable Cox regression analyses were used to calculate hazard ratios, according to the duration of survival.

Results

The conditional 5-year disease-specific survival in patients with regional or localized chordoma was relatively stable over time, whereas in patients with distant chordoma, there was a gradual improvement. The conditional 5-year disease-specific survival (DSS) of patients older than 60 years old and patients with a tumor size between 5 and 10 cm improved. Interestingly, for patients with a tumor larger than 10 cm, the conditional 5-year DSS decreased over time. After surviving 5 years, the hazard ratio (HR) of patients older than 60 years old decreased from 1.33 to 1.24, that of patients with a tumor size between 5 and 10 cm decreased from 1.61 to 1.52 and that of patients with distant metastasis decreased from 3.30 to 1.09. However, after surviving 5 years, the HR of patients with a tumor size larger than 10 cm increased from 2.33 to 3.77, that of patients who underwent surgical resection increased from 0.37 to 0.58 and that of patients who received radiation therapy increased from 0.81 to 1.04.

Conclusion

Age at diagnosis, tumor size and disease stage can influence conditional survival for patients with chordoma. The HR of different factors will change over the survival time. Therefore, understanding the changing risk profile and conditional 5-year DSS of chordoma is critical for accurate clinical treatment guidance.

Pediatric extraosseous sacral chordoma: case report and literature review of embryonic derivation and clinical implications

An extraosseous intradural presentation for a sacral chordoma in the pediatric age group has not been reported to date. This is a report on an 11-year-old boy who presented with an extraosseous, intradural sacral chordoma. He underwent gross-total resection and received adjuvant proton beam therapy. Neoplastic transformation of the notochord is reviewed to illustrate the developmental basis for the surgical anatomy and pathogenesis of the classic chordoma variant. Clinical and pathological features are reviewed to differentiate this chordoma presentation from classic osseous chordomas and ecchordosis physaliphora, a related benign developmental notochordal lesion. Finally, the role of developmental signaling in the pathogenesis of chordomas from postembryonic notochordal tissue is discussed.

Robotic Surgery Assisted Staged En-Bloc Sacrectomy for Sacral Chordoma: A Case Report

CASE

Two male patients aged 37 years and 39 years, diagnosed with sacral chordoma, underwent robotic-assisted preparatory adhesiolysis from the anterior aspect of the tumor, followed by posterior en-bloc partial sacrectomy. The average total operative time was 360 minutes (anterior docking + anterior console + posterior excision), and mean blood loss was 930 mL. Both patients were mobilized early, had no postoperative complications, and were free of local recurrence at 18 month of follow-up.

CONCLUSIONS

Robotic-assisted surgery is a novel, valid, safe, and minimally invasive technique which drastically reduces the associated surgical complications of single-staged posterior sacrectomy, resulting in excellent functional and oncological outcome.

Predictive Value of Preoperative Magnetic Resonance Imaging Findings for Survival and Local Recurrence in Patients Undergoing En Bloc Resection of Sacral Chordomas

BACKGROUND

Few studies have assessed the prognostic importance of preoperative magnetic resonance imaging (MRI) scan findings in patients undergoing en bloc resection of sacral chordomas.

OBJECTIVE

To (1) report in-depth imaging characteristics of sacral chordomas, (2) describe the patterns of local and distant recurrence, and (3) determine imaging predictors of overall survival (OS) and local recurrence (LR).

METHODS

This retrospective case series was obtained from a prospectively maintained spine database from 1995 to 2016. All patients underwent en bloc resection of sacral chordomas. Detailed demographic, outcome, and MRI data were collected. A survival analysis was completed with multivariable cox regression to assess the impact of MRI findings on OS and LR.

RESULTS

A total of 41 patients underwent en bloc resection of sacral chordoma with preoperative MRI scans. Tumor characteristics included lobulated: (93%) and soft tissue tail (54%). The following areas had tumor invasion lobulated: sacroiliac (SI) joint (15%), ilium (5%), piriformis (61%), gluteus (46%), subcutaneous fat (32%), and lumbosacral venous plexus (22%). After multivariable analysis, only subcutaneous fat extension was an independent predictor of decreased OS (hazard ratio 5.30, 95% confidence interval 1.47-19.19, P = .011). Though not significant after multivariable analysis, the following factors were significant predictors of LR after univariate logrank testing: above the L5/S1 disc space (P = .004), SI joint invasion (P = .036), and piriformis extension (P = .022).

CONCLUSION

The presence of subcutaneous fat extension was an independent predictor of decreased OS. Other MRI findings with potential for future evaluation include size, presence of soft tissue tail, extension above L5/S1, and SI joint and piriformis invasion.

Adjuvant gamma knife surgery and image-guided, intensity-modulated radiation therapy for the treatment of sacral chordomas

Aim

The aim of this study was to confirm whether patients with sacral chordoma benefit from adjuvant radiotherapy and to determine the optimal photon radiotherapy module for comprehensive treatment.

Background

Chordoma is a rare slow-growing neoplasm arisen from cellular remnants of the notochord. About 50% occur in the sacrococcygeal region. Surgical resection and adjuvant radiation therapy are recommended treatment due to the improving local control rate.

Materials and methods

118 patients treated by surgery and adjuvant radiotherapy from August 2003 to May 2015 were retrospectively analyzed. All patients received surgical resection after diagnosis. Among these patients, 44 were treated by exclusive surgery, and 48 were treated with adjuvant image-guided, intensity-modulated radiation therapy (IG-IMRT). In addition, 26 patients were treated with gamma knife surgery (GKS) after surgical resection. The median follow-up was 54 months for all patients. Kaplan-Meier analysis was used to calculate recurrence-free survival (RFS) overall survival (OS).

Results

Patients treated with adjuvant radiotherapy had better RFS (p = 0.014) than those treated exclusively by surgery. The patients in the IG-IMRT group exhibited better recurrence-free survival (p = 0.01) than the GKS group. Moreover, in the IG-IMRT group, patients treated by higher dose were associated with better RFS (p = 0.04). No significant difference in OS was found. No grade 3 late toxicity was found.

Conclusions

We confirmed that adjuvant radiotherapy improved RFS but not OS in sacral chordoma patients after surgery. Furthermore, favorable RFS and low adverse event rates were observed following IG-IMRT. Our results suggest that high dose IG-IMRT is an appropriate module of adjuvant radiotherapy for sacral chordoma patients.

Comparison of radiomics machine-learning classifiers and feature selection for differentiation of sacral chordoma and sacral giant cell tumour based on 3D computed tomography features

OBJECTIVE

We aimed to identify optimal machine-learning methods for preoperative differentiation of sacral chordoma (SC) and sacral giant cell tumour (SGCT) based on 3D non-enhanced computed tomography (CT) and CT-enhanced (CTE) features.

METHODS

A total of 95 patients were divided into a training set and a validation set. Three best feature selection methods (Relief, least absolute shrinkage and selection operator (LASSO) and Random Forest (RF)) and three classification methods, including generalised linear models (GLM), support vector machines (SVM) and RF, were compared for their performance in distinguishing SC and SGCT. The performance of the radiomics model was investigated via area under the receiver-operating characteristic curve (AUC) and accuracy (ACC) analysis.

RESULTS

The selection method LASSO + classifier GLM had the highest AUC of 0.984 and ACC of 0.897 in the validating set, followed by Relief + GLM (AUC = 0.909, ACC = 0.862) and LASSO + SVM (AUC = 0.900, ACC = 0.862) based on CTE features. For CT features, RF + GLM had the highest AUC of 0.889, while LASSO + GLM achieved a high ACC of 0.793 in the validating set. Regardless of the methods, CTE features significantly outperformed those from CT for the differentiation of SC and SGCT (Z_AUC = -3.029, Z_ACC = -4.553; p < 0.05).

CONCLUSIONS

Our study demonstrated CTE features performed better than CT features. The selection method LASSO + classifier GLM had the best performance in differentiation of SC and SGCT, which could enhance the application of radiomics methods in sacral tumours.

KEY POINTS

• Sacral chordoma and sacral giant cell tumour are the two most common primary tumours of the sacrum with many common clinical and imaging characteristics. • A radiomics model helps clinicians to identify the histology of a sacral tumour. • CTE features should be preferred.

Role of the Apparent Diffusion Coefficient as a Predictor of Tumor Progression in Patients with Chordoma

BACKGROUND AND PURPOSE

Diffusion-weighted imaging may aid in distinguishing aggressive chordoma from nonaggressive chordoma. This study explores the prognostic role of the apparent diffusion coefficient in chordomas.

MATERIALS AND METHODS

Sixteen patients with residual or recurrent chordoma were divided postoperatively into those with an aggressive tumor, defined as a growing tumor having a doubling time of <1 year, and those with a nonaggressive tumor on follow-up MR images. The ability of the ADC to predict an aggressive tumor phenotype was investigated by receiver operating characteristic analysis. The prognostic role of ADC was assessed using a Kaplan-Meier curve with a log-rank test.

RESULTS

Seven patients died during a median follow-up of 48 months (range, 4-126 months). Five of these 7 patients were in the aggressive tumor group, and 2 were in the nonaggressive tumor group. The mean ADC was significantly lower in the aggressive tumor group than in the nonaggressive tumor group (P = .002). Receiver operating characteristic analysis showed that a cutoff ADC value of 1.494 × 10^-3 × mm²/s could be used to diagnose aggressive tumors with an area under the curve of 0.983 (95% CI, 0.911-1.000), a sensitivity of 1.000 (95% CI, 0.541-1.000), and a specificity of 0.900 (95% CI, 0.555-0.998). Furthermore, a cutoff ADC of ≤1.494 × 10^-3 × mm²/s was associated with a significantly worse prognosis (P = .006).

CONCLUSIONS

Lower ADC values could predict tumor progression in postoperative chordomas.

Initial Experience with Intraoperative Phosphorous-32 Brachytherapy During Resection of Malignant Spinal Tumors

INTRODUCTION

Brachytherapy is a major adjuvant modality for neoplasms, but few have trialed its use for spinal tumors. This study examines perioperative and oncologic outcomes of patients with malignant spinal tumors who underwent resection with intraoperative phosphorous-32 (P32) brachytherapy.

METHODS

Consecutive adult patients who underwent P32 brachytherapy during malignant spinal tumor resection were retrospectively identified from 2014 to 2015. Complications, tumor recurrence, and survival were reviewed. A comprehensive review of the literature was performed.

RESULTS

A total of 8 patients were included. Average age was 54.3 years, and 25.0% were males. Tumor types included metastatic leiomyosarcoma, chordoma, multifocal recurrent ependymomas, breast metastasis, malignant meningioma, and myxofibrosarcoma. One-half of patients underwent en bloc tumor resection. P32 plaques were applied to 2 sites per patient for mean 13.1 minutes per site with a goal penetration of 10 Gy to 1-mm depth. Perioperative complications occurred in 3 patients (37.5%), including a persistent cerebral spinal fluid leak, deep infection requiring reoperation, and sacral insufficiency fracture. At a mean 25.6 months follow-up, local recurrence rate was 25.0%, and overall survival was 75.0%. Mean time to recurrence was 14.4 months. Survival at 6, 12, 18, and 24 months was 100.0%, 100.0%, 85.7%, and 71.4%, respectively.

CONCLUSIONS

The use of P32 is safe and feasible. P32 intraoperative brachytherapy does not seem to increase the rate of complications. The sample size of this series is small with heterogeneity in tumor type, but recurrence and survival outcomes seem promising compared with previous reports. Further clinical trials are needed.

Prognostic Factors and Survival Outcome in Patients with Chordoma in the United States: A Population-Based Analysis

OBJECTIVE

To evaluate prognostic factors of patients with chordoma through a population-based analysis.

METHODS

Surveillance, Epidemiology, and End Results (SEER) database was queried for patients with chordoma from 1973 to 2013. Kaplan-Meier univariate analysis and Cox regression multivariate analysis were performed to examine prognostic factors in overall survival (OS) and disease-specific survival (DSS).

RESULTS

One thousand five hundred ninety-eight patients with chordoma are identified. Kaplan-Meier analysis showed that OS and DSS were 61% and 71% at 5 years and 41% and 57% at 10 years. Multivariate Cox regression analysis demonstrated that independent predictors of OS and DSS are age at diagnosis (hazard ratio [HR]= 2.80 [95% confidence interval {CI}, 2.12-3.70], P < 0.001; HR = 1.60 [95% CI, 1.18-2.16], P = 0.002), surgical treatment (HR = 0.62 [95% CI, 0.52-0.73], P < 0.001; HR = 0.64 [95% CI, 0.52-0.79], P < 0.001), radiation therapy (HR = 1.23 [95% CI, 1.07-1.42], P = 0.004; HR = 1.29 [95% CI, 1.09-1.54], P = 0.004), tumor size (HR = 1.53 [95% CI, 1.32-1.78], P < 0.001; HR = 1.62 [95% CI, 1.35-1.94], P < 0.001) and distant metastasis (HR = 3.40 [95% CI, 2.45-4.71], P < 0.001; HR = 3.77 [95% CI, 2.61-5.45], P < 0.001).

CONCLUSION

We report the largest study to date to evaluate prognostic factors of patients with chordoma. Multivariate analysis demonstrated that older age, greater tumor size, and distant metastasis were correlated with decreased survival, whereas surgical resection was correlated with increased survival. Patients receiving radiation therapy also showed decreased survival, likely an indication of the patients' advanced stage of disease, making them poor surgical candidates.

Whole-transcriptome analysis of chordoma of the skull base

Fourteen skull base chordoma specimens and three normal specimens were microdissected from paraffin-embedded tissue. Pools of RNA from highly enriched preparations of these cell types were subjected to expression profiling using whole-transcriptome shotgun sequencing. Using strict criteria, 294 differentially expressed transcripts were found, with 28 % upregulated and 72 % downregulated. The transcripts were annotated using NCBI Entrez Gene and computationally analyzed with the Ingenuity Pathway Analysis program. From these significantly changed expressions, the analysis identified 222 cancer-related transcripts. These 294 differentially expressed genes and non-coding RNA transcripts provide here a set to specifically define skull base chordomas and to identify novel and potentially important targets for diagnosis, prognosis, and therapy of this cancer. Significance Genomic profiling to subtype skull base chordoma reveals potential candidates for specific biomarkers, with validation by IHC for selected candidates. The highly expressed developmental genes T, LMX1A, ZIC4, LHX4, and HOXA1 may be potential drivers of this disease.