Photon Irradiation for Spinal Chordomas and Chondrosarcomas




Abstract


While surgical excision represents the primary curative modality for chondrosarcomas and chordomas, tumor-free surgical margins can be difficult or impossible to achieve in the spine without significant morbidity. Therefore, additional therapy is usually needed for durable local control. Adjuvant radiotherapy to a minimum of 60–65 Gy is recommended following incomplete resection or positive margins, though data are limited to largely retrospective series. Radiotherapy has also been given preoperatively in conjunction with a postoperative boost. The advent of intensity-modulated radiation therapy has allowed safer delivery of higher doses of radiation to spinal tumors with conventional fractionation. Perhaps more promising, however, is the emergence of stereotactic radiosurgery to deliver high-dose radiotherapy to tumors with a steep dose gradient around the spinal cord. By overcoming radioresistance typically associated with chordoma and chondrosarcoma, stereotactic radiosurgery may offer definitive local control as a surgical replacement or adjuvant.




Keywords

Chondrosarcoma, Chordoma, External beam radiation, Image-guided radiation therapy, Mobile spine, Photon irradiation, Sacrum, Stereotactic radiosurgery

 






  • Outline



  • Introduction 355



  • External Beam Radiotherapy With Conventional Fractionation 356



  • Stereotactic Radiosurgery 356



  • Radiation Toxicity 361



  • Conclusions 361



  • References 361


© 2018 Elsevier Inc. All rights reserved. Please note that the copyright for the original figures submitted by the contributors is owned by Contributors.




Introduction


Chordoma is a rare malignancy arising from remnants of the embryonic notochord at an estimated incidence of <1 per 100,000 and a median age at diagnosis of 59 years. Most chordomas present in the spine, either the mobile spine (53%) or the sacral/coccygeal spine (47%), as opposed to cranial, extra-axial, or other sites. Overall survival rates for chordoma have been reported to be 68% at 5 years and 40% at 10 years.


Chondrosarcoma is a type of sarcoma that produces a cartilaginous matrix. It is also rare, with an estimated annual incidence of 1 in 200,000. About 7%–10% occur in the mobile spine and 5% in the sacrum.


Although chordoma and chondrosarcoma are often considered to be slow growing, both tumors, even when of low malignant grade, can cause significant morbidity and mortality when located in the spine. Traditional treatment approaches include surgery, either en bloc or intralesional resection, and radiotherapy. En bloc resection with wide margins is superior to intralesional resection in achieving local control and cure, but such tumor-free surgical margins can be difficult to achieve in the spine without significant morbidity in some cases because of tumor proximity to the spinal cord and vertebral arteries. Therefore, additional therapy is needed for durable local control in cases of incomplete resection.


Radiation therapy has been given for spinal chordomas and chondrosarcomas in preoperative, adjuvant, and definitive settings. Radiation modalities include external beam radiotherapy with photons or charged particles such as protons and cobalt, and intraoperative plaque brachytherapy.


Herein, we discuss and review photon external beam radiation for spinal chordomas and chondrosarcomas. There are no randomized control trials to demonstrate the optimal use of radiotherapy in this setting but rather retrospective series predominately limited to fewer than 50 patients. Photon radiotherapy, administered as stereotactic radiosurgery in conventional fractionation or hypofractionated schemes, may improve local tumor control and patient survival.




External Beam Radiotherapy With Conventional Fractionation


Photon external beam radiotherapy has been utilized for spinal chordomas and chondrosarcomas for many years in preoperative, postoperative, salvage, and palliative settings with standard fractionation ( Table 33.1 ). Photon external beam radiation was initially given with two-dimensional techniques and later three-dimensional treatment planning and conformal radiation therapy. However, since these techniques were limited in conformity, radiation dose was limited by the radiation tolerance of spinal cord and nearby organs such as kidneys and bowel. For the last 15 years, the superior dose geometry achievable by intensity-modulated radiation therapy (IMRT) technology has enabled delivery of higher radiation dose to the tumor target while excluding the spinal cord from dose that exceeds its tolerance ( Fig. 33.1 ).



Table 33.1

Photon External Beam Radiation Therapy With Conventional Fractionation for Spinal Chordomas and Chondrosarcomas


























































































































































Study Time Period Histology N Location ( n ) Surgery ( n ) RT Details Follow-Up Length Outcomes
Shives et al. 1916–81 Chondrosarcoma 20 Cervical (4), thoracic (11), lumbar (5) En bloc resection (2), intralesional excision or marginal excision (18) Postop RT in 5 pt s s/p intralesional excision, dose range 17.8–60 Gy Med 6 y Mean survival for RT patients 6.7 y, not different from surgery only mean survival 5.5 y
Keisch et al. 1949–86 Chordoma 21 Clivus/cranial (6), spine (1), sacrum (3) Complete resection (1), subtotal resection (16), biopsy only (4) Postop RT s/p subtotal resection in 4 pts and definitive RT in 4 pts, med dose 60 Gy/30 fx (range 35–70 Gy) Med 19 y with a min of 2.5 y 5 y OS 74%, 10 y OS 46%, OS better in surgery alone or surgery + RT groups than RT alone group, lumbrosacral tumors s/p surgery + RT DFS 6.6 y compared to surgery alone DFS 4.1 y
Catton et al. 1958–92 Chordoma 48 Skull base (20), spine (5), sacrum (23) Complete resection w/positive margin (4), biopsy or subtotal resection (44) RT in 41 total pts, for 26 pts med dose 5 Gy/25 fx (range 25–60 Gy), 2 pts 24 Gy/3 fx, 8 pts 40 Gy/44 fx/14 days Not reported, 36/45 pts followed until death 5 y OS 54%, 10 y OS 20%, med survival 62 mos overall and 18 mos after retreatment, no difference in OS for <50 Gy compared to >50 Gy
York et al. 1954–94 Chordoma 27 Sacrum (27) En bloc resection (15), subtotal excision (12) Postop RT s/p subtotal excision or salvage RT for 18 cases, med dose 60 Gy Med 3.6 y Addition of postop RT after subtotal excision prolonged DFS from 8 mos to 2.3 y
York et al. 1954–97 Chondrosarcoma 21 Cervical (4), thoracic (10), lumbar (7) Radical (6), subtotal (21) Postop RT in 9 cases, salvage RT in 2 cases, med dose 50 Gy Med 5.7 y 5 y OS 64%, 10 y OS 40%, RT prolonged DFI from 1.3 y to 3.7 y but not SS
Cheng et al. 1965–96 Chordoma 23 Lumbar (6), sacrum (17) Radical (7), subtotal or positive margin (16) Postop RT and salvage RT used in some patients, med dose 54 Gy (range 40–70 Gy) Med 7.1 y 5 y OS 86%, 10 y OS 49%, 5 y LC 60%, 10 y LC 43%, RT for positive margins associated with longer DFS and less LF
Boriani et al. 1954–91 Chordoma 52 Cervical (15), thoracic (7), lumbar (30) En bloc resection (18), intralesional excision (24) Postop RT in 24 pts (s/p intralesional or en bloc resection), definitive RT in 10 pts, mean dose 40–44 Gy/20 fx LR in 66%, RT alone, intralesional excision, or both all experienced LR at <2 y
Terezakis et al. 2001–05 Chordoma (7), sarcoma (18), ependymoma (2) 27 Paraspinal Partially resected or unresected Med dose 66 Gy/33 fx (range 54–70 Gy) with IMRT Med 17.4 mos 2 y LC 65%, 2 y OS 79%, 84% reported no pain or improved pain at last follow-up
DeLaney et al. 1998–2005 Chordoma (29), chondrosarcoma (14), other (7) 50 Thoracic (11), lumbar (13), sacrum (26) Gross total resection (25), subtotal resection (12), biopsy (13) 50.4 Gy for subclinical disease, 70.2 Gy for microscopic disease, and 77.4 Gy for gross disease with photons and protons (preop dose 19.8 Gy for sacral sites and 50.4 Gy for other sites) Med 48 mos 5 y LC 78%, 5 y OS 87%, higher LF for patients treated for recurrent disease
Wagner et al. 1982–2006 Chordoma (25), chondrosarcoma (15), osteosarcoma (4), Ewing sarcoma (2), other (2) 48 Axial spine (10), sacrum/pelvis (34), long bones (4) Med preop dose 20 Gy/11 fx, med postop dose 50.4 Gy with photons and protons med 31.8 mos 5 y OS 65%, 5 y LC 72%
Zabel-du Bois et al. 2000–09 Chordoma 34 Sacrum (34) Complete resection (4), positive microscopic margin (4), gross residual tumor (16), biopsy only (4) Postop RT in 13 pts, definitive RT in 4 pts, salvage RT for some pts, med dose 66 Gy/33 fx (range 54–72 Gy) with IMRT Med 4.5 y Actuarial LC 79% 1 y, 55% 2 y, 27% 5 y, OS 97% 1 y, 91% 2 y, 70% 5 y, LC higher for pts treated initial instead of salvage and for doses >60 Gy
Potluri et al. 1996–2009 Chordoma (14), chondrosarcoma (5) 19 Skull base/cranial (11), cervical (5), thoracic (1), lumbar (1) Maximal tumor debulking (18), no surgery (1) 50–60 Gy preop then postop boost to residual tumor to 65–70 Gy Med 4.4 y Chordoma 5 y OS 92% and LC 83%, chondrosarcoma 5 y OS and LC 100%, GTV >30 cm 3 associated w/LR
Schoenfeld et al. 1984–2006 Chordoma, chondrosarcoma 21 Cervical (5), thoracic (14), lumbar (2) En bloc resection (8) or intralesional (13) RT in 20 pts, either 20 Gy preop with 50 Gy postop or 50.4 Gy preop with 19.8 Gy postop boost for +margin, ±IORT for dural disease min 2 y 1 y OS 90%, 5 y OS 61%, 24 pts LR (all s/p intralesional resection) and 43% DM
Dhawale et al. 1985–2010 Chordoma 21 Sacrum (21) En bloc resection (14), subtotal resection (7) Postop RT in 18 pts, mean dose 56 Gy (conventional and IMRT) Med 5.8 y 40% LR and 19% DM, mean interval to recurrence 2.5 y, med OS 7.2 y

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Feb 21, 2019 | Posted by in NEUROSURGERY | Comments Off on Photon Irradiation for Spinal Chordomas and Chondrosarcomas
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