Perspectives Commentary on: Skull Base Chordoma and Chondrosarcoma: Influence of Clinical and Demographic Factors on Prognosis: A SEER Analysis by Bohman et al. World Neurosurg 82:806-814, 2014
Skull Base Chordomas and Chondrosarcomas: A Population-Based Analysis Hormuzdiyar H. Dasenbrock and E. Antonio Chiocca
hordomas are very rare tumors that are hypothesized to arise from notochord remnants and to have an estimated incidence of 0.8/100,000 in the American population. Although the majority of chordomas arise from the sacrum, approximately 35% arise from the clivus and another 15% are seen in the spinal column. Patients with chordomas of the skull base typically present with cranial neuropathies from local mass effect but may also present with symptoms attributable to suprasellar extension, brainstem compression, or neurovascular encasement. Chordomas are indolent, slow-growing tumors that are histologically benign (8). However, their natural history can be anything but benign: chordomas have the potential to be locally aggressive, with high rates of recurrence and a predilection to seed any contaminated area of the operative field (5).
C
function and minimizing postoperative morbidity also are important considerations. Given the substantial variability in the precise location of clival chordomas and their adjacent extension, the best operative approach must be considered for each tumor. Several different open surgical approaches have been described, including transmaxillary, translabial, frontal orbitozygomatic, transpetrosal, and transcondylar (1, 12, 17, 23). However, endoscopic endonasal approaches to the clivus have been used increasingly, with authors reporting excellent local control and minimal postoperative morbidity (15, 16, 22). Cranial neuropathies and cerebrospinal fluid leakage are the most common immediate postoperative complications, but cerebrovascular injury is another potential devastating complication because of the encasement of vascular structures by the tumor.
Although much of the morbidity and mortality of chordomas is attributable to local disease, distant metastases also are rarely seen (28). Chondrosarcomas are histologically distinct tumors that also have a propensity to arise from the clivus; although patients with chondrosarcomas often have a similar presentation to chordomas, those with the former tumor are known to have a more favorable prognosis (2). Given the large tumor burden of chordomas upon presentation and their often-intimate association with critical neurological and vascular structures, the treatment of chordomas and chondrosarcomas, especially in the skull base, is particularly challenging (28).
Several retrospective, institutional studies have suggested that greater extent of surgical resection is associated with improved long-term local control and overall survival (6, 10, 14, 24-26). Given the comparatively indolent nature of the growth of chordomas, long-term follow-up, i.e., 5 10 years postoperatively, is needed to appropriately assess the validity of a treatment modality. In a recent systematic review and meta-analysis of these observational studies, Di Maio et al. (13) found that 5-year progression-free survival and overall survival were significantly improved for patients in whom a complete resection was achieved. Additionally, given the relative rarity and complexity of skull base chordomas, some have advocated the centralization of these complex procedures at high-volume centers, and in another population-based study, Jones et al. (21) suggest that outcomes may be improved for patients who undergo surgical resection at high-volume centers.
The initial standard of care for patients with clival chordomas is radical surgical resection: resection of the tumor and drilling the adjacent bone (1). Although the primary goal of the surgical resection is an oncologic resection, preservation of neurological
Key words Chondrosarcoma - Chordoma - Outcomes - Prognosis - Skull base -
468
Abbreviations and Acronyms SEER: Surveillance, Epidemiology, and End Results
www.SCIENCEDIRECT.com
Department of Neurosurgery, Harvard Medical School, Institute for the Neurosciences at the Brigham and Women’s/Faulkner Hospital, and Center for Neuro-oncology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA To whom correspondence should be addressed: E. Antonio Chiocca, M.D., Ph.D. [E-mail: [email protected]] Citation: World Neurosurg. (2015) 83, 4:468-470. http://dx.doi.org/10.1016/j.wneu.2014.08.049
WORLD NEUROSURGERY, http://dx.doi.org/10.1016/j.wneu.2014.08.049
PERSPECTIVES
The precise role for radiation therapy in the treatment of chordomas remains controversial. One commonly used modality of irradiation in this patient population is adjuvant postoperative proton-beam radiation (4, 19). However, substantial variability in the timing and modality of radiation exits in clinical practice. Some have suggested that adjuvant radiation be used to improve local control for all patients after surgical resection, whereas others have reserved radiation for patients with gross residual tumor or local recurrence. In rare cases, stereotactic radiosurgery alone has been used for skull base chordomas (11, 18). Additionally, several different modalities of radiation treatment have been described for skull base chordomas and chondrosarcomas, including traditional photon based radiation, stereotactic radiosurgery, highdensity proton beam, and carbon ion (9, 11, 18-20, 27). Although the data on the utility of radiation have been conflicting, a recent systematic review by Amichetti et al. (3) found improved local control when adjuvant postoperative proton radiation was used. Although randomized, controlled trials remain the current goldstandard for high-quality data in the era of evidence-based medicine, the relative rarity of clival chordomas and chondrosarcomas makes the implementation of such a trial logistically challenging. Additionally, the substantial variability in the exact clival location, surrounding local extension, and adjacent neurovascular encasement of each skull base chordoma highlights that an individualized approach is of the utmost importance for each tumor. However, this variability limits the ability to standardize treatment, particularly operative regimens, for these lesions and further limits the logistical implementation of a randomized controlled trial. The majority of studies that have been published on the outcomes of patients undergoing treatment for skull base chordomas have been single-institution—often single-surgeon— retrospective case series. Although these analyses have been critical in understanding surgical nuances and postoperative complications, including the potential to seed the operative field for patients undergoing treatment of Chordomas (5), the generalizability of these studies may be limited. Moreover, although conducting a meta-analysis of observational studies is an additional strategy to increase the sample size of a study, these meta-analyses are hindered by the inherent biases of the studies that they compile. Therefore, those with chordomas and chondrosarcomas of the skull base may be a particularly good patient population to study using large nationwide databases, such as the Surveillance, Epidemiology, and End Results (SEER) database of the National Cancer Institute. In a recent issue of WORLD NEUROSURGERY, Bohman et al. (7) use the SEER database to evaluate the factors that impact long-term, tumor-specific and overall survival for patients with skull base chordomas and condrosarcomas. They found that patients with a diagnosis of chondrosarcoma had improved survival compared with those with chordomas in multivariate analyses. Older age and greater tumor size were found to be associated with inferior survival for patients with chordoma; for those with condrosarcoma, older age, earlier decade of diagnosis, and mesenchymal subtype were associated with poor survival. Adjuvant radiation was not found to improve outcomes for patients with either tumor histology. There are many important advantages to selecting population databases to study the outcomes of patients undergoing
WORLD NEUROSURGERY 83 [4]: 468-470, APRIL 2015
treatment of clival chordomas and chondrosarcomas. National databases are particularly useful in analyzing patients with relatively rare conditions, where the number of patients in specific studies may be small. These databases significantly increase the sample size for analyses compared with institutional retrospective reviews, without further augmenting the inherent biases of these retrospective reviews that are a potential limitation of metaanalyses of observational studies. Greater sample size increases the statistical power to analyze outcomes. Data on specific variables that may be important confounders can often be extracted from these data sets, such as race, socioeconomic status, insurance coverage, and hospital volume. Specific databases, including the SEER database, have collected data for many decades, allowing for the evaluation of long-term outcomes. Perhaps most critical, however, is that large population-based data sets provide a national perspective, allowing for much broader and potentially more generalizable data than that from single-surgeon or institutional reviews. For example, Bohman et al. have shown in this study that 5-year and 10-year survival for patients with skull base chordomas and condrosarcomas are both much lower than what has been previously reported from institutional analyses. Although it is difficult to determine whether the exact percentages remain applicable to patients who present today (as the study includes patients who presented from 1983 to 2009), these data on survival may be more applicable to the general population than previously reported percentages from institutional data. Additionally, the findings from the SEER database help confirm at a national level that patients with chondrosarcomas have a comparatively indolent course and better prognosis than those with a skull base chordoma (2). Nonetheless, there are important limitations of national databases, which must be considered when evaluating the data and conclusions from such studies. Although national data sets include specific factors that may not be easily evaluated in institutional reviews, there are also critical variables that cannot be obtained. In this study by Bohman et al., data were not available on the precise tumor location and local extension of the tumor, on the baseline and postoperative neurological deficits, on the surgical approach that was selected, on the postoperative complications, and on the modality, duration, and indications for radiation. The lack of data on these key factors greatly limits the ability to make specific conclusions from national datasets. Bohman et al. also did not find that the addition of radiation improved survival for patients with chordomas or chondrosarcomas in multivariate analysis, although 10-year overall survival was improved for patients with skull base chondrosarcomas who underwent radiation in univariate analysis. However, as mentioned already, there was a relative paucity of data available from SEER regarding the timing, duration, and modality of radiation in this study. Thus, it is difficult to ascertain whether the lack of a survival benefit for those who received adjuvant radiation was caused by a lack of treatment benefit or to variability in radiation regimens. The authors of “Skull Base Chordoma and Chondrosarcoma: Influence of Clinical and Demographic Factors on Prognosis: A SEER Analysis” are to be commended for performing an elegant population-based study evaluating the variables that impact 5- and 10-year survival for patients with skull base
www.WORLDNEUROSURGERY.org
469
PERSPECTIVES
chordomas and condrosarcomas. However, as is oft the case, this well-designed study has further shown areas in which highquality data are lacking, with potential important clinical implications. The fact that no clear survival benefit was seen for subjects undergoing adjuvant radiation further adds to the growing body of literature evaluating this controversial topic. As the authors suggest, given the logistical barriers with conducting a randomized,
REFERENCES 1. al-Mefty O, Borba LA: Skull base chordomas: a management challenge. J Neurosurg 86:182-189, 1997. 2. Almefty K, Pravdenkova S, Colli BO, Al-Mefty O, Gokden M: Chordoma and chondrosarcoma: similar, but quite different, skull base tumors. Cancer 110:2457-2467, 2007. 3. Amichetti M, Cianchetti M, Amelio D, Enrici RM, Minniti G: Proton therapy in chordoma of the base of the skull: a systematic review. Neurosurg Rev 32:403-416, 2009. 4. Ares C, Hug EB, Lomax AJ, Bolsi A, Timmermann B, Rutz HP, Schuller JC, Pedroni E, Goitein G: Effectiveness and safety of spot scanning proton radiation therapy for chordomas and chondrosarcomas of the skull base: first longterm report. Int J Radiat Oncol Biol Phys 75: 1111-1118, 2009. 5. Arnautovic KI, Al-Mefty O: Surgical seeding of chordomas. Neurosurg Focus 10:E7, 2001. 6. Bloch OG, Jian BJ, Yang I, Han SJ, Aranda D, Ahn BJ, Parsa AT: A systematic review of intracranial chondrosarcoma and survival. J Clin Neurosci 16:1547-1551, 2009. 7. Bohman LE, Koch M, Bailey RL, AlonsoBasanta M, Lee JY: Skull Base Chordoma and Chondrosarcoma: Influence of Clinical and Demographic Factors on Prognosis; A SEER analysis. World Neurosurg 82:806-814, 2014. 8. Chambers KJ, Lin DT, Meier J, Remenschneider A, Herr M, Gray ST: Incidence and survival patterns of cranial chordoma in the United States. Laryngoscope 124:1097-1102, 2014. 9. Chang SD, Martin DP, Lee E, Adler JR Jr: Stereotactic radiosurgery and hypofractionated stereotactic radiotherapy for residual or recurrent cranial base and cervical chordomas. Neurosurg Focus 10:E5, 2001. 10. Colli BO, Al-Mefty O: Chordomas of the skull base: follow-up review and prognostic factors. Neurosurg Focus 10:E1, 2001. 11. Dassoulas K, Schlesinger D, Yen CP, Sheehan J: The role of Gamma Knife surgery in the treatment
470
www.SCIENCEDIRECT.com
controlled trial for patients with these rare tumors, high-quality registries with prospectively collected data may be another study design that may help further understand the role of radiation in this patient population. Nonetheless, the onus is on the neurosurgical, oncological, and radiation oncological community to provide high-quality data evaluating the impact of adjuvant radiation on the outcomes of patients with skull base chordomas.
of skull base chordomas. J Neurooncol 94:243-248, 2009.
the Surveillance, Epidemiology, and End Results (SEER) database. J Clin Neurosci 2014.
12. Di Maio S, Rostomily R, Sekhar LN: Current surgical outcomes for cranial base chordomas: cohort study of 95 patients. Neurosurgery 70:1355-1360: discussion 1360, 2012.
22. Komotar RJ, Starke RM, Raper DM, Anand VK, Schwartz TH: The endoscope-assisted ventral approach compared with open microscope-assisted surgery for clival chordomas. World Neurosurg 76:318-327,: discussion 259-362, 2011.
13. Di Maio S, Temkin N, Ramanathan D, Sekhar LN: Current comprehensive management of cranial base chordomas: 10-year meta-analysis of observational studies. J Neurosurg 115:1094-1105, 2011. 14. Eid AS, Chang UK, Lee SY, Jeon DG: The treatment outcome depending on the extent of resection in skull base and spinal chordomas. Acta Neurochir (Wien) 153:509-516, 2011. 15. Fraser JF, Nyquist GG, Moore N, Anand VK, Schwartz TH: Endoscopic endonasal minimal access approach to the clivus: case series and technical nuances. Neurosurgery 67:ons150-158,: discussion ons158, 2010. 16. Fraser JF, Nyquist GG, Moore N, Anand VK, Schwartz TH: Endoscopic endonasal transclival resection of chordomas: operative technique, clinical outcome, and review of the literature. J Neurosurg 112:1061-1069, 2010. 17. Gay E, Sekhar LN, Rubinstein E, Wright DC, Sen C, Janecka IP, Snyderman CH: Chordomas and chondrosarcomas of the cranial base: results and follow-up of 60 patients. Neurosurgery 36: 887-896,: discussion 896-887, 1995. 18. Hasegawa T, Ishii D, Kida Y, Yoshimoto M, Koike J, Iizuka H: Gamma Knife surgery for skull base chordomas and chondrosarcomas. J Neurosurg 107:752-757, 2007.
23. Lanzino G, Dumont AS, Lopes MB, Laws ER Jr: Skull base chordomas: overview of disease, management options, and outcome. Neurosurg Focus 10:E12, 2001. 24. Sekhar LN, Pranatartiharan R, Chanda A, Wright DC: Chordomas and chondrosarcomas of the skull base: results and complications of surgical management. Neurosurg Focus 10:E2, 2001. 25. Sen C, Triana AI, Berglind N, Godbold J, Shrivastava RK: Clival chordomas: clinical management, results, and complications in 71 patients. J Neurosurg 113:1059-1071, 2010. 26. Tzortzidis F, Elahi F, Wright D, Natarajan SK, Sekhar LN: Patient outcome at long-term followup after aggressive microsurgical resection of cranial base chordomas. Neurosurgery 59: 230-237,: discussion 230-237, 2006. 27. Uhl M, Mattke M, Welzel T, Roeder F, Oelmann J, Habl G, Jensen A, Ellerbrock M, Jakel O, Haberer T, Herfath K, Debus J: Highly effective treatment of skull base chordoma with carbon ion irradiation using a raster scan technique in 155 patients: First long-term results. Cancer 120: 3410-3417, 2014. 28. Walcott BP, Nahed BV, Mohyeldin A, Coumans JV, Kahle KT, Ferreira MJ: Chordoma: current concepts, management, and future directions. Lancet Oncol 13:e69-76, 2012.
19. Hug EB: Review of skull base chordomas: prognostic factors and long-term results of protonbeam radiotherapy. Neurosurg Focus 10:E11, 2001. 20. Jian BJ, Bloch OG, Yang I, Han SJ, Aranda D, Tihan T, Parsa AT: Adjuvant radiation therapy and chondroid chordoma subtype are associated with a lower tumor recurrence rate of cranial chordoma. J Neurooncol 98:101-108, 2010.
Citation: World Neurosurg. (2015) 83, 4:468-470. http://dx.doi.org/10.1016/j.wneu.2014.08.049 Journal homepage: www.WORLDNEUROSURGERY.org Available online: www.sciencedirect.com
21. Jones PS, Aghi MK, Muzikansky A, Shih HA, Barker FG 2nd, Curry WT Jr: Outcomes and patterns of care in adult skull base chordomas from
1878-8750/$ - see front matter ª 2015 Published by Elsevier Inc.
WORLD NEUROSURGERY, http://dx.doi.org/10.1016/j.wneu.2014.08.049
Skull Base Chordomas and Chondrosarcomas: A Population-Based Analysis Hormuzdiyar H. Dasenbrock and E. Antonio Chiocca
hordomas are very rare tumors that are hypothesized to arise from notochord remnants and to have an estimated incidence of 0.8/100,000 in the American population. Although the majority of chordomas arise from the sacrum, approximately 35% arise from the clivus and another 15% are seen in the spinal column. Patients with chordomas of the skull base typically present with cranial neuropathies from local mass effect but may also present with symptoms attributable to suprasellar extension, brainstem compression, or neurovascular encasement. Chordomas are indolent, slow-growing tumors that are histologically benign (8). However, their natural history can be anything but benign: chordomas have the potential to be locally aggressive, with high rates of recurrence and a predilection to seed any contaminated area of the operative field (5).
C
function and minimizing postoperative morbidity also are important considerations. Given the substantial variability in the precise location of clival chordomas and their adjacent extension, the best operative approach must be considered for each tumor. Several different open surgical approaches have been described, including transmaxillary, translabial, frontal orbitozygomatic, transpetrosal, and transcondylar (1, 12, 17, 23). However, endoscopic endonasal approaches to the clivus have been used increasingly, with authors reporting excellent local control and minimal postoperative morbidity (15, 16, 22). Cranial neuropathies and cerebrospinal fluid leakage are the most common immediate postoperative complications, but cerebrovascular injury is another potential devastating complication because of the encasement of vascular structures by the tumor.
Although much of the morbidity and mortality of chordomas is attributable to local disease, distant metastases also are rarely seen (28). Chondrosarcomas are histologically distinct tumors that also have a propensity to arise from the clivus; although patients with chondrosarcomas often have a similar presentation to chordomas, those with the former tumor are known to have a more favorable prognosis (2). Given the large tumor burden of chordomas upon presentation and their often-intimate association with critical neurological and vascular structures, the treatment of chordomas and chondrosarcomas, especially in the skull base, is particularly challenging (28).
Several retrospective, institutional studies have suggested that greater extent of surgical resection is associated with improved long-term local control and overall survival (6, 10, 14, 24-26). Given the comparatively indolent nature of the growth of chordomas, long-term follow-up, i.e., 5 10 years postoperatively, is needed to appropriately assess the validity of a treatment modality. In a recent systematic review and meta-analysis of these observational studies, Di Maio et al. (13) found that 5-year progression-free survival and overall survival were significantly improved for patients in whom a complete resection was achieved. Additionally, given the relative rarity and complexity of skull base chordomas, some have advocated the centralization of these complex procedures at high-volume centers, and in another population-based study, Jones et al. (21) suggest that outcomes may be improved for patients who undergo surgical resection at high-volume centers.
The initial standard of care for patients with clival chordomas is radical surgical resection: resection of the tumor and drilling the adjacent bone (1). Although the primary goal of the surgical resection is an oncologic resection, preservation of neurological
Key words Chondrosarcoma - Chordoma - Outcomes - Prognosis - Skull base -
468
Abbreviations and Acronyms SEER: Surveillance, Epidemiology, and End Results
www.SCIENCEDIRECT.com
Department of Neurosurgery, Harvard Medical School, Institute for the Neurosciences at the Brigham and Women’s/Faulkner Hospital, and Center for Neuro-oncology, Dana-Farber Cancer Institute, Boston, Massachusetts, USA To whom correspondence should be addressed: E. Antonio Chiocca, M.D., Ph.D. [E-mail: [email protected]] Citation: World Neurosurg. (2015) 83, 4:468-470. http://dx.doi.org/10.1016/j.wneu.2014.08.049
WORLD NEUROSURGERY, http://dx.doi.org/10.1016/j.wneu.2014.08.049
PERSPECTIVES
The precise role for radiation therapy in the treatment of chordomas remains controversial. One commonly used modality of irradiation in this patient population is adjuvant postoperative proton-beam radiation (4, 19). However, substantial variability in the timing and modality of radiation exits in clinical practice. Some have suggested that adjuvant radiation be used to improve local control for all patients after surgical resection, whereas others have reserved radiation for patients with gross residual tumor or local recurrence. In rare cases, stereotactic radiosurgery alone has been used for skull base chordomas (11, 18). Additionally, several different modalities of radiation treatment have been described for skull base chordomas and chondrosarcomas, including traditional photon based radiation, stereotactic radiosurgery, highdensity proton beam, and carbon ion (9, 11, 18-20, 27). Although the data on the utility of radiation have been conflicting, a recent systematic review by Amichetti et al. (3) found improved local control when adjuvant postoperative proton radiation was used. Although randomized, controlled trials remain the current goldstandard for high-quality data in the era of evidence-based medicine, the relative rarity of clival chordomas and chondrosarcomas makes the implementation of such a trial logistically challenging. Additionally, the substantial variability in the exact clival location, surrounding local extension, and adjacent neurovascular encasement of each skull base chordoma highlights that an individualized approach is of the utmost importance for each tumor. However, this variability limits the ability to standardize treatment, particularly operative regimens, for these lesions and further limits the logistical implementation of a randomized controlled trial. The majority of studies that have been published on the outcomes of patients undergoing treatment for skull base chordomas have been single-institution—often single-surgeon— retrospective case series. Although these analyses have been critical in understanding surgical nuances and postoperative complications, including the potential to seed the operative field for patients undergoing treatment of Chordomas (5), the generalizability of these studies may be limited. Moreover, although conducting a meta-analysis of observational studies is an additional strategy to increase the sample size of a study, these meta-analyses are hindered by the inherent biases of the studies that they compile. Therefore, those with chordomas and chondrosarcomas of the skull base may be a particularly good patient population to study using large nationwide databases, such as the Surveillance, Epidemiology, and End Results (SEER) database of the National Cancer Institute. In a recent issue of WORLD NEUROSURGERY, Bohman et al. (7) use the SEER database to evaluate the factors that impact long-term, tumor-specific and overall survival for patients with skull base chordomas and condrosarcomas. They found that patients with a diagnosis of chondrosarcoma had improved survival compared with those with chordomas in multivariate analyses. Older age and greater tumor size were found to be associated with inferior survival for patients with chordoma; for those with condrosarcoma, older age, earlier decade of diagnosis, and mesenchymal subtype were associated with poor survival. Adjuvant radiation was not found to improve outcomes for patients with either tumor histology. There are many important advantages to selecting population databases to study the outcomes of patients undergoing
WORLD NEUROSURGERY 83 [4]: 468-470, APRIL 2015
treatment of clival chordomas and chondrosarcomas. National databases are particularly useful in analyzing patients with relatively rare conditions, where the number of patients in specific studies may be small. These databases significantly increase the sample size for analyses compared with institutional retrospective reviews, without further augmenting the inherent biases of these retrospective reviews that are a potential limitation of metaanalyses of observational studies. Greater sample size increases the statistical power to analyze outcomes. Data on specific variables that may be important confounders can often be extracted from these data sets, such as race, socioeconomic status, insurance coverage, and hospital volume. Specific databases, including the SEER database, have collected data for many decades, allowing for the evaluation of long-term outcomes. Perhaps most critical, however, is that large population-based data sets provide a national perspective, allowing for much broader and potentially more generalizable data than that from single-surgeon or institutional reviews. For example, Bohman et al. have shown in this study that 5-year and 10-year survival for patients with skull base chordomas and condrosarcomas are both much lower than what has been previously reported from institutional analyses. Although it is difficult to determine whether the exact percentages remain applicable to patients who present today (as the study includes patients who presented from 1983 to 2009), these data on survival may be more applicable to the general population than previously reported percentages from institutional data. Additionally, the findings from the SEER database help confirm at a national level that patients with chondrosarcomas have a comparatively indolent course and better prognosis than those with a skull base chordoma (2). Nonetheless, there are important limitations of national databases, which must be considered when evaluating the data and conclusions from such studies. Although national data sets include specific factors that may not be easily evaluated in institutional reviews, there are also critical variables that cannot be obtained. In this study by Bohman et al., data were not available on the precise tumor location and local extension of the tumor, on the baseline and postoperative neurological deficits, on the surgical approach that was selected, on the postoperative complications, and on the modality, duration, and indications for radiation. The lack of data on these key factors greatly limits the ability to make specific conclusions from national datasets. Bohman et al. also did not find that the addition of radiation improved survival for patients with chordomas or chondrosarcomas in multivariate analysis, although 10-year overall survival was improved for patients with skull base chondrosarcomas who underwent radiation in univariate analysis. However, as mentioned already, there was a relative paucity of data available from SEER regarding the timing, duration, and modality of radiation in this study. Thus, it is difficult to ascertain whether the lack of a survival benefit for those who received adjuvant radiation was caused by a lack of treatment benefit or to variability in radiation regimens. The authors of “Skull Base Chordoma and Chondrosarcoma: Influence of Clinical and Demographic Factors on Prognosis: A SEER Analysis” are to be commended for performing an elegant population-based study evaluating the variables that impact 5- and 10-year survival for patients with skull base
www.WORLDNEUROSURGERY.org
469
PERSPECTIVES
chordomas and condrosarcomas. However, as is oft the case, this well-designed study has further shown areas in which highquality data are lacking, with potential important clinical implications. The fact that no clear survival benefit was seen for subjects undergoing adjuvant radiation further adds to the growing body of literature evaluating this controversial topic. As the authors suggest, given the logistical barriers with conducting a randomized,
REFERENCES 1. al-Mefty O, Borba LA: Skull base chordomas: a management challenge. J Neurosurg 86:182-189, 1997. 2. Almefty K, Pravdenkova S, Colli BO, Al-Mefty O, Gokden M: Chordoma and chondrosarcoma: similar, but quite different, skull base tumors. Cancer 110:2457-2467, 2007. 3. Amichetti M, Cianchetti M, Amelio D, Enrici RM, Minniti G: Proton therapy in chordoma of the base of the skull: a systematic review. Neurosurg Rev 32:403-416, 2009. 4. Ares C, Hug EB, Lomax AJ, Bolsi A, Timmermann B, Rutz HP, Schuller JC, Pedroni E, Goitein G: Effectiveness and safety of spot scanning proton radiation therapy for chordomas and chondrosarcomas of the skull base: first longterm report. Int J Radiat Oncol Biol Phys 75: 1111-1118, 2009. 5. Arnautovic KI, Al-Mefty O: Surgical seeding of chordomas. Neurosurg Focus 10:E7, 2001. 6. Bloch OG, Jian BJ, Yang I, Han SJ, Aranda D, Ahn BJ, Parsa AT: A systematic review of intracranial chondrosarcoma and survival. J Clin Neurosci 16:1547-1551, 2009. 7. Bohman LE, Koch M, Bailey RL, AlonsoBasanta M, Lee JY: Skull Base Chordoma and Chondrosarcoma: Influence of Clinical and Demographic Factors on Prognosis; A SEER analysis. World Neurosurg 82:806-814, 2014. 8. Chambers KJ, Lin DT, Meier J, Remenschneider A, Herr M, Gray ST: Incidence and survival patterns of cranial chordoma in the United States. Laryngoscope 124:1097-1102, 2014. 9. Chang SD, Martin DP, Lee E, Adler JR Jr: Stereotactic radiosurgery and hypofractionated stereotactic radiotherapy for residual or recurrent cranial base and cervical chordomas. Neurosurg Focus 10:E5, 2001. 10. Colli BO, Al-Mefty O: Chordomas of the skull base: follow-up review and prognostic factors. Neurosurg Focus 10:E1, 2001. 11. Dassoulas K, Schlesinger D, Yen CP, Sheehan J: The role of Gamma Knife surgery in the treatment
470
www.SCIENCEDIRECT.com
controlled trial for patients with these rare tumors, high-quality registries with prospectively collected data may be another study design that may help further understand the role of radiation in this patient population. Nonetheless, the onus is on the neurosurgical, oncological, and radiation oncological community to provide high-quality data evaluating the impact of adjuvant radiation on the outcomes of patients with skull base chordomas.
of skull base chordomas. J Neurooncol 94:243-248, 2009.
the Surveillance, Epidemiology, and End Results (SEER) database. J Clin Neurosci 2014.
12. Di Maio S, Rostomily R, Sekhar LN: Current surgical outcomes for cranial base chordomas: cohort study of 95 patients. Neurosurgery 70:1355-1360: discussion 1360, 2012.
22. Komotar RJ, Starke RM, Raper DM, Anand VK, Schwartz TH: The endoscope-assisted ventral approach compared with open microscope-assisted surgery for clival chordomas. World Neurosurg 76:318-327,: discussion 259-362, 2011.
13. Di Maio S, Temkin N, Ramanathan D, Sekhar LN: Current comprehensive management of cranial base chordomas: 10-year meta-analysis of observational studies. J Neurosurg 115:1094-1105, 2011. 14. Eid AS, Chang UK, Lee SY, Jeon DG: The treatment outcome depending on the extent of resection in skull base and spinal chordomas. Acta Neurochir (Wien) 153:509-516, 2011. 15. Fraser JF, Nyquist GG, Moore N, Anand VK, Schwartz TH: Endoscopic endonasal minimal access approach to the clivus: case series and technical nuances. Neurosurgery 67:ons150-158,: discussion ons158, 2010. 16. Fraser JF, Nyquist GG, Moore N, Anand VK, Schwartz TH: Endoscopic endonasal transclival resection of chordomas: operative technique, clinical outcome, and review of the literature. J Neurosurg 112:1061-1069, 2010. 17. Gay E, Sekhar LN, Rubinstein E, Wright DC, Sen C, Janecka IP, Snyderman CH: Chordomas and chondrosarcomas of the cranial base: results and follow-up of 60 patients. Neurosurgery 36: 887-896,: discussion 896-887, 1995. 18. Hasegawa T, Ishii D, Kida Y, Yoshimoto M, Koike J, Iizuka H: Gamma Knife surgery for skull base chordomas and chondrosarcomas. J Neurosurg 107:752-757, 2007.
23. Lanzino G, Dumont AS, Lopes MB, Laws ER Jr: Skull base chordomas: overview of disease, management options, and outcome. Neurosurg Focus 10:E12, 2001. 24. Sekhar LN, Pranatartiharan R, Chanda A, Wright DC: Chordomas and chondrosarcomas of the skull base: results and complications of surgical management. Neurosurg Focus 10:E2, 2001. 25. Sen C, Triana AI, Berglind N, Godbold J, Shrivastava RK: Clival chordomas: clinical management, results, and complications in 71 patients. J Neurosurg 113:1059-1071, 2010. 26. Tzortzidis F, Elahi F, Wright D, Natarajan SK, Sekhar LN: Patient outcome at long-term followup after aggressive microsurgical resection of cranial base chordomas. Neurosurgery 59: 230-237,: discussion 230-237, 2006. 27. Uhl M, Mattke M, Welzel T, Roeder F, Oelmann J, Habl G, Jensen A, Ellerbrock M, Jakel O, Haberer T, Herfath K, Debus J: Highly effective treatment of skull base chordoma with carbon ion irradiation using a raster scan technique in 155 patients: First long-term results. Cancer 120: 3410-3417, 2014. 28. Walcott BP, Nahed BV, Mohyeldin A, Coumans JV, Kahle KT, Ferreira MJ: Chordoma: current concepts, management, and future directions. Lancet Oncol 13:e69-76, 2012.
19. Hug EB: Review of skull base chordomas: prognostic factors and long-term results of protonbeam radiotherapy. Neurosurg Focus 10:E11, 2001. 20. Jian BJ, Bloch OG, Yang I, Han SJ, Aranda D, Tihan T, Parsa AT: Adjuvant radiation therapy and chondroid chordoma subtype are associated with a lower tumor recurrence rate of cranial chordoma. J Neurooncol 98:101-108, 2010.
Citation: World Neurosurg. (2015) 83, 4:468-470. http://dx.doi.org/10.1016/j.wneu.2014.08.049 Journal homepage: www.WORLDNEUROSURGERY.org Available online: www.sciencedirect.com
21. Jones PS, Aghi MK, Muzikansky A, Shih HA, Barker FG 2nd, Curry WT Jr: Outcomes and patterns of care in adult skull base chordomas from
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