The treatment outcome depending on the extent of resection in skull base and spinal chordomas

Radiotherapy for Mobile Spine and Sacral Chordoma: A Critical Review and Practical Guide from the Spine Tumor Academy

Chordomas are rare tumors of the embryologic spinal cord remnant. They are locally aggressive and typically managed with surgery and either adjuvant or neoadjuvant radiation therapy. However, there is great variability in practice patterns including radiation type and fractionation regimen, and limited high-level data to drive decision making. The purpose of this manuscript was to summarize the current literature specific to radiotherapy in the management of spine and sacral chordoma and to provide practice recommendations on behalf of the Spine Tumor Academy. A systematic review of the literature was performed using the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) approach. Medline and Embase databases were utilized. The primary outcome measure was the rate of local control. A detailed review and interpretation of eligible studies is provided in the manuscript tables and text. Recommendations were defined as follows: (1) consensus: approved by >75% of experts; (2) predominant: approved by >50% of experts; (3) controversial: not approved by a majority of experts. Expert consensus supports dose escalation as critical in optimizing local control following radiation therapy for chordoma. In addition, comprehensive target volumes including sites of potential microscopic involvement improve local control compared with focal targets. Level I and high-quality multi-institutional data comparing treatment modalities, sequencing of radiation and surgery, and dose/fractionation schedules are needed to optimize patient outcomes in this locally aggressive malignancy.

Incidence, Management, and Outcomes of Adult Spinal Chordoma Patients in the United States

STUDY DESIGN

Retrospective cohort study.

OBJECTIVE

Spinal chordomas are rare primary malignant neoplasms of the primitive notochord. They are slow growing but locally aggressive lesions that have high rates of recurrence and metastasis after treatment. Gold standard treatment remains en-bloc surgical resection with questionable efficacy of adjuvant therapies such as radiation and chemotherapy. Here we provide a comprehensive analysis of prognostic factors, treatment modalities, and survival outcomes in patients with spinal chordoma.

METHODS

Patients with diagnosis codes specific for chordoma of spine, sacrum, and coccyx were queried from the National Cancer Database (NCDB) during the years 2004-2016. Outcomes were investigated using Cox univariate and multivariate regression analyses, and survival curves were generated for comparative visualization.

RESULTS

1,548 individuals were identified with a diagnosis of chordoma, 60.9% of which were at the sacrum or coccyx and 39.1% at the spine. The mean overall survival of patients in our cohort was 8.2 years. Increased age, larger tumor size, and presence of metastases were associated with worsened overall survival. 71.2% of patients received surgical intervention and both partial and radical resection were associated with significantly improved overall survival (P < 0.001). Neither radiotherapy nor chemotherapy administration improved overall survival; however, amongst patients who received radiation, those who received proton-based radiation had significantly improved overall survival compared to traditional radiation.

CONCLUSION

Surgical resection significantly improves overall survival in patients with spinal chordoma. In those patients receiving radiation, those who receive proton-based modalities have improved overall survival. Further studies into proton radiotherapy doses are required.

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.

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.

Clivus chordomas: Heterogeneous tumor extension requires adapted surgical approaches

OBJECTIVE

Clivus chordomas are semi-malignant, but infiltratively growing tumors. Currently, a widely-accepted treatment concept encompasses maximal, but safe, surgical resection and radiotherapy. Caused by the size and the tumor extension, different surgical approaches, especially in recurrent cases, might be necessary.

METHODS

Retrospective review of 50 patients on whom 70 surgeries were performed: 29 in primary and 41 in recurrent cases. Based on MRI images, all cases were asserted according to the size and the extension of the tumor. Used surgical approaches were evaluated. Postoperative complications, neurological function prior to and after the surgery, the extent of tumor resection on postoperative MR images were assessed and progression-free survival was calculated.

RESULTS

Tumor size was estimated as small (< 5 cm³) in 8, as medium (5-20 cm³) in 21, as large (20-100 cm³) in 17, and as giant (> 100 cm³) in 4 patients. Most frequently used surgical approaches in primary cases were the transsphenoidal one and midfacial degloving (51.7 % and 17.2 %, respectively). In recurrent cases, dependent on the tumor extension, transsphenoidal (21.9 %), retrosigmoidal (29.3 %), and pterional (19.5 %) approaches, as well as midfacial degloving (17.1 %) were used. Due to the vast tumor extension and infiltration, gross total or near total resection could be achieved in 12 patients (24 %), only. There was no mortality and no major complications in primary cases. In recurrences, however, postoperative hemorrhages and strokes emerged in 4.9 % and 7.1 %. Minor complications occurred in 17.1 % and were dominated by CSF leaks (12.2 %), both in primary in recurrent cases. While most cranial nerve impairments were caused by tumor infiltration of the cavernous sinus, and hence have not improved by treatment, the sixth nerve palsy as a consequence of tumor mass compression, could significantly be improved by surgery. Following surgery, patients were subjected to radiotherapy (68.9 % for primary cases, and 36.6 % for recurrences) mainly with carbon ions. Overall, 5-year progression-free survival was 44.7 %.

CONCLUSION

Caused by the heterogenous pattern of growth of clivus chordomas, surgical approaches should be chosen individually. Vast and infiltrative tumor extension constitute major limitations of surgical resection, and hence result in poor progression-frees survival.

Local and Distant Recurrence in Resected Sacral Chordomas: A Systematic Review and Pooled Cohort Analysis

STUDY DESIGN

Systematic review.

OBJECTIVES

Sacral chordomas are rare, primary tumors of the spine, best treated with en bloc resection. The purpose of this study was to assess the literature for resected sacral chordoma and to quantify the prevalence of, risk factors for, and treatment outcomes of local and distant recurrence therein.

METHODS

We searched 5 online databases from January 1980 to May 2016 to find articles that report survival, recurrence outcomes, and/or prognostic factors for the resected sacral chordoma patient population. Characteristics and clinical outcomes of the pooled cohort are reported. Fisher exact tests, unpaired t tests, and one-way analysis of variance were used to investigate patient- and treatment-associated prognostic factors for local and distant recurrence. Survival analyses were performed for time to local recurrence and death. The protocol's PROSPERO ID is CRD42015024384.

RESULTS

Fifty-seven studies, with 1235 unique sacral chordoma patients, were included in this review. Local and distant recurrence occurred in 42.6% and 22.4% of patients with adequate follow-up, respectively. Kaplan-Meier overall median survival for patients with and without recurrence were 98 and 209 months after surgery, respectively. Wide surgical margin was associated with a lower rate of local recurrence; and wide surgical margin, female sex, and patient age ≥65 years were associated with lower rates of distant recurrence.

CONCLUSIONS

While surgical margin remains the most significant prognostic factor for local and distant recurrence, combined surgical approach may be associated with local recurrence. Male sex and age <65 years may be associated with distant recurrence. Patients with risk factors for recurrence should undergo close monitoring to maximize survival.

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.

Management of Sacrococcygeal Chordoma: A Systematic Review and Meta-analysis of Observational Studies

STUDY DESIGN

Systematic review and meta-analysis of observational studies.

OBJECTIVE

The aim of the study is to evaluate different treatment modalities in the management of sacrococcygeal chordoma.

SUMMARY OF BACKGROUND DATA

Chordomas are primary malignant bone tumors associated with considerable morbidity and mortality.

METHODS

We searched MEDLINE, EMBASE, Cochrane Central-Register of Controlled Trials, and Scopus from inception to July 2015. Eligible studies included patients with sacrococcygeal chordoma treated exclusively with surgery, radiotherapy, or both. Two reviewers independently assessed the eligibility of potential studies, risk of bias, and extracted data. Outcomes of interest were all-cause mortality, progression-free survival, and metastases. We analyzed further surgical outcomes by resection margin. All outcomes were assessed at 60 months and more than 60 months following intervention.

RESULTS

We included 33 noncomparative studies reporting on 501 patients (mean age 57 years). Overall mortality rate was (16%) after surgical resection with adjuvant radiotherapy and (28%) after surgical resection, and (43%) after radiotherapy (P = 0.28). All-cause mortality following wide surgical resection was (32%) compared to (40%) after marginal resection (P = 0.51). Overall progression-free survival rate was (58%) after surgical resection with adjuvant radiotherapy and (55%) after surgery (P = 0.92). However, at more than 60 months follow-up, progression-free survival rates were significantly higher (P = 0.024) following surgical resection with adjuvant radiotherapy (74%) in comparison to surgery (55%) and radiotherapy (36%). Overall progression-free survival rates were nonsignificantly higher after wide surgical resection (66%) than marginal resection (33%) (P = 0.16). However, at 60 months follow-up, progression-free survival rates were significantly higher following wide surgical resection (73%) than marginal resection (33%) (P = 0.047).

CONCLUSION

Sacrococcygeal chordoma is a difficult to treat disease entity. Until comparative studies become available, wide surgical resection and multidisciplinary management are the recommended approaches to improve patient outcomes.

LEVEL OF EVIDENCE

3.

Prognostic Factors in Patients With Spinal Chordoma: An Integrative Analysis of 682 Patients

BACKGROUND

The low incidence of spinal chordoma precludes a prospective study of prognostic factors with a large patient cohort.

OBJECTIVE

To perform a comprehensive integrative analysis on the prognostic factors, treatment, and outcomes of patients with spinal chordoma using data from 2 institutions and the literature.

METHODS

Appropriate studies were identified per search criteria. The local database was retrospectively searched to include a similar patient cohort.

RESULTS

Overall, 108 studies from the literature and 30 patients from our local institution were identified, resulting in a total of 682 patients. The median age was 57 years old and 35.2% were female. The median follow-up was 46 months (range: 1-408). The median progression-free survival (PFS) and overall survival (OS) were 72 months and 115 months, respectively. Significant prognostic factors for PFS on multivariate analysis included age (pediatric vs adult, hazard ratio [HR]: 2.00-14.36), tumor location (mobile spine vs sacral spine, HR: 0.31-0.87), pathology (differentiated vs classic, HR: 2.48-10.90),and chemotherapy (HR:1.11-3.85). Significant prognostic factors for OS on multivariate analysis included age (geriatric vs adult, HR: 1.52-3.45 and pediatric vs adult, HR: 1.73-9.36), bladder or bowel dysfunction (HR: 1.27-5.43), pathology (dedifferentiated vs classic, HR: 2.38-11.09), recurrence or progression (HR: 1.72-4.48), and metastases (HR: 1.11-2.47).

CONCLUSION

In patients with spinal chordoma, young age, location in sacral spine, dedifferentiated pathology, and chemotherapy were negative predictors of PFS, while young and old age, bladder or bowel dysfunction at presentation, dedifferentiated pathology, recurrence or progression, and metastases portended a worse OS.

Surgical Consideration for Adolescents and Young Adults With Cervical Chordoma

STUDY DESIGN

Retrospective study.

OBJECTIVE

The aim of this study was to compare the clinical outcomes between adolescent and young adult (AYA) patients and old adult patients with cervical chordoma who were treated surgically and present the surgical consideration for adolescents and young adults with cervical chordoma.

SUMMARY OF BACKGROUND DATA

With predominance in senior patients, chordoma is distinctively rare in AYAs. Because of the rarity of AYA chordoma, individual case report represents most of the literature on this disease entity on mobile spine and lack of long-term follow up, which leads to the paucity of clinical evidence for treatment planning and prognosis prediction.

METHODS

A retrospective study was conducted to investigate the prognosis of AYA patients with cervical chordoma who were treated surgically. We collected the clinical data of these patients and their older counterparts, and further compared the prognosis of the patients in different age groups. To estimate survival curves, Kaplan-Meier method was used, and significance was assessed using a log-rank test.

RESULTS

Forty consecutive patients with chordoma of the cervical spine treated in our institution were included in the study. Two groups were identified according to age. Group 1 comprised children and adolescents (age ≤ 25 yrs; n = 9) and Group 2 comprised adults (age > 25 years; n = 31). In comparison, Group 1 was featured by significantly higher rate of recurrence and shorter overall survival, although no difference found in the surgical modality between two groups.

CONCLUSION

There is a dismal prognosis in young patients with chordoma, and thus support the notion that as radical a total en bloc spondylectomy (TES) of the lesions as possible may benefit the overall survival of these young patients. Although the ensuing neurological deficits may be devastating, it will be worth sacrificing if the life expectancy of these young patients is prolonged.

LEVELS OF EVIDENCE

4.

Single-Fraction Spine Stereotactic Body Radiation Therapy for the Treatment of Chordoma

PURPOSE

Chordoma is a radioresistant tumor that presents a therapeutic challenge with spine involvement, as high doses of radiation are needed for local control while limiting dose to the spinal cord. The purpose of this study is to determine the efficacy and safety of single-fraction spine stereotactic body radiation therapy for the treatment of spine chordoma.

METHODS

A retrospective review of our institutional database from 2006 to 2013 identified 8 patients (12 cases) with chordoma of the spine who were treated with spine stereotactic body radiation therapy. Surgical resection was performed in 7 of the 12 cases. The treatment volume was defined by the bony vertebral level of the tumor along with soft tissue extension appreciated on magnetic resonance imaging fusion. Medical records and imaging were assessed for pain relief and local control. Treatment toxicity was evaluated using Common Terminology Criteria for Adverse Events version 4.0.

RESULTS

Median age was 59 years (range, 17-91). Median target volume was 48 cm³ (1-304), and median prescription dose was 16 Gy (11-16). Median conformality index was 1.44 (1.14-3.21), and homogeneity index was 1.12 (1.05-1.19). With a median follow-up time of 9.7 months (.5-84), local control was achieved in 75% of the cases treated. One patient developed limited grade 2 spinal cord myelopathy that resolved with steroids. There were no other treatment toxicities from spine stereotactic body radiation therapy.

CONCLUSION

Single-fraction spine stereotactic body radiation therapy can be safely delivered to treat chordoma of the spine with the potential to improve pain symptoms. Although the early data are suggestive, long-term follow-up with more patients is necessary to determine the efficacy of spine stereotactic body radiation therapy in the treatment of chordoma of the spine.

OUTCOME OF CLIVAL CHORDOMAS AFTER SKULL BASE SURGERIES WITH MEAN FOLLOW-UP OF 10 YEARS

BACKGROUND AND OBJECTIVE

Skull base chordomas are clinically malignant because of the difficulty of total removal, high recurrence rate, and occasional drop metastasis. Although aggressive surgical resection and postoperative radiation have been recommended, the long-term outcome remains unsatisfactory.

METHODS

From 1992 to 2011, we treated 24 patients with skull base chordoma using aggressive surgical removal as a principal strategy. Skull base approaches were selected according to tumor extension to remove the tumor and surrounding bone as completely as possible. After surgery, all patients were closely observed with MRI to find small and localized recurrent tumors, which were treated with gamma-knife radiosurgery or surgical resection. The mean postoperative follow-up duration was 10.2 years (range, 1-17.2 years).

RESULTS

The 5-, 10-, and 15-year overall survival rates were 86%, 72%, and 72%, respectively. The 5- and 10-year progression-free survival rates were 47% and 35%, respectively. Tumor extension to the brainstem and partial tumor removal were the factors related to poor survival.

CONCLUSIONS

Our results suggest that aggressive surgical removal improves the long-term outcome of patients with skull base chordoma. We would like to emphasize that skull base chordomas should be aggressively removed using various skull base approaches.

Adjuvant Stereotactic Radiosurgery and Radiation Therapy for the Treatment of Intracranial Chordomas

Objective Chordomas are locally aggressive, highly recurrent tumors requiring adjuvant radiotherapy following resection for successful management. We retrospectively reviewed patients treated for intracranial chordomas with adjuvant stereotactic radiosurgery (SRS) and stereotactic radiation therapy (SRT). Methods A total of 57 patients underwent 83 treatments at the UCLA Medical Center between February 1990 and August 2011. Mean follow-up was 57.8 months. Mean tumor diameter was 3.36 cm. Overall, 8 and 34 patients received adjuvant SRS and SRT, and the mean maximal dose of radiation therapy was 1783.3 cGy and 6339 cGy, respectively. Results Overall rate of recurrence was 51.8%, and 1- and 5-year progression-free survival (PFS) was 88.2% and 35.2%, respectively. Gross total resection was achieved in 30.9% of patients. Adjuvant radiotherapy improved outcomes following subtotal resection (5-year PFS 62.5% versus 20.1%; p = 0.036). SRS and SRT produced comparable rates of tumor control (p = 0.28). Higher dose SRT (> 6,000 cGy) (p = 0.013) and younger age (< 45 years) (p = 0.03) was associated with improved rates of tumor control. Conclusion Adjuvant radiotherapy is critical following subtotal resection of intracranial chordomas. Adjuvant SRT and SRS were safe and improved PFS following subtotal resection. Higher total doses of SRT and younger patient age were associated with improved rates of tumor control.

Proton therapy for sarcomas

Sarcomas are a heterogeneous group of tumors that can occur in a wide array of anatomic sites and age ranges with varying histologies. Proton beam therapy, as compared with advanced x-ray radiation therapy techniques, can substantially lower dose to nontarget tissues. This dosimetric advantage can potentially allow for improvement of the therapeutic ratio in the treatment of many of the sarcomas by either increasing the local control, via increased dose to the target, or by decreasing the normal tissue complications, via lowered dose to the avoidance structures. This article reviews the key dosimetric studies and clinical outcomes published to date documenting the potential role proton beam therapy may play in the treatment of sarcomas.

Male sex as a risk factor for the clinical course of skull base chordomas

Object

Chordomas of the skull base are rare and locally invasive and have a poor prognosis. The aim of this retrospective multicenter study was to evaluate the current pattern of care and clinical course and to identify prognostic factors.

Methods

A total of 47 patients (26 men; mean age 48.5 years) treated in 5 centers were included. Histology was centrally reviewed; additionally, semiquantitative N- and E-cadherin expression analysis was performed. Prognostic factors were obtained from multivariate regression models. For survival analysis the Kaplan-Meier method was used.

Results

The median follow-up period was 5.2 years. Complete resection, incomplete resection, and extended biopsy were performed in 14.9%, 80.9%, and 4.3% of patients, respectively. Surgical morbidity was not associated with extent of resection. Adjuvant radiation therapy was performed in 30 (63.8%) of 47 patients. The median progression-free survival (PFS) was 7.3 years. Complete resection prolonged median overall survival (OS) (p = 0.04). Male patients presented with worse PFS (4.8 years vs 9.8 years; p = 0.04) and OS (8.3 years vs not reached; p = 0.03) even though complete resection was exclusively achieved in the male subpopulation. Multivariate analysis confirmed male sex as the most important risk factor for tumor progression (p = 0.04) and death (p = 0.02). Age, duration of symptoms, initial Karnofsky Performance Scale score, brainstem compression, involvement of the petrous bone, infiltration of the dura mater, modality and dose of radiation therapy, and the E- and N-cadherin expression patterns did not gain prognostic relevance.

Conclusions

In skull base chordomas, male patients bear a higher risk of progressive disease and death. Male patients might benefit from more aggressive adjuvant therapy and/or from a closer follow-up schedule.

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

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