2. EPIDEMIOLOGY
• The skeleton - 3rd most common place for metastasis after liver and lungs
• ~70% of lung, prostate, and breast cancers — develop bony metastasis.
• Spine - skeletal structure most frequently affected by cancer.
{The spine > pelvis > femur >humerus>ribs>skull}.
• Peak incidence - 40 - 65 yrs (period of highest risk for cancer).
3. Modes of spread
• Arterial route - most common method of transmission owing to the extensive blood
supply along the vertebral column
• Batsons plexus - valveless system of veins (connecting the thoracic and pelvic
vessels to the basivertebral veins)
• CSF
• Direct extension
6. Pain
• Most commonly presenting symptom - 85% to 95% of patients
• Back pain in a cancer patient is metastatic disease until proven otherwise.
• Usually precedes the development of neurologic symptoms by several weeks/months.
• Early diagnosis of metastatic spinal disease - important factor affecting the prognosis
• Two distinct types of back pain are encountered in patients with spine tumors:
BIOLOGICAL and MECHANICAL
8. • The goal of imaging is to be 100% sensitive and specific in identifying tumor, giving
precise anatomic detail, identifying distant metastases, and showing recurrent tumor
following the placement of instrumentation.
• No single imaging modality accomplishes all of these goals, but understanding the
advantages and disadvantages of different imaging modalities will assist the clinician
with patient screening and treatment planning
9. Plain Radiographs
• At least 50% of the vertebral body must be
compromised before the abnormality can be identified.
• Metastatic tumor - infiltrates the bone marrow of the
vertebral body without destroying the cortical bone.
• Compression and burst fractures are readily identified.
• Can identify deformities in a weight-bearing state
• Dynamic films - detect instability
• Following surgery - best imaging modality for
assessing spinal alignment
10. Bone Scan
• Screening tool
• Reveals metastatic lesions at an earlier stage when compared to plain
radiographs.
• Relies on an osteoblastic reaction
• Destructive tumors may not be detected.
• Low specificity for cancer
• Paraspinal tumors that enter the epidural space through the neural
foramen - often not detected.
• inflammation or infection - possible differential diagnoses
• Poor degree of detail - CT/MRI is mandatory for surgical planning.
• FDG PET - has replaced bone scan.
11. CT
• more than 90% sensitivity and specificity for
bone structures
• assessing the degree of bone destruction and
pathologic fractures
• for differentiating between osteolytic and
osteoblastic lesions
• Limited visualization of the surrounding soft
tissue.
• CT Myelogram - Post spinal reconstruction
with placement of metallic instrumentation,
radiosurgery treatment planning.
12. CT guided biopsy
• diagnostic accuracy - 77% to 97%.
• Gold standard
• Single best investigation to be done
13. MRI
• most sensitive and specific
• Hybrid scans of the brachial or
lumbosacral plexus may reveal tumor in
patients with extremity weakness.
• T2-weighted imaging - Tumor is
hyperintense relative to marrow.
• STIR - enhanced contrast between the
marrow (hypointense) and tumor
(hyperintense).
• STIR - most sensitive but give less
anatomic detail.
• Whole spine screening - due to high
rate of multiple noncontiguous lesions.
15. Angiography
• Highly vascular tumours - Renal cell carcinoma, thyroid carcinoma, hepatocellular
carcinoma, and neuroendocrine tumors.
• preoperative tumor embolization - for decreasing the amount of intraoperative blood
loss.
16. FDG-PET
• Less predictive in differentiating osteoblastic tumors from
benign pathology.
• 18(F)-FDG PET-CT has greater specificity for detecting
spine metastases than either 18(F)- FDG PET or CT
alone.
• Useful in directing the biopsy.
• Other radionuclide scans - 131I scans for papillary thyroid
cancer, metaiodobenzylguani- dine (MIBG) scans for
neuroblastoma, and somatostatin scans for
neuroendocrine tumors.
18. Hypercalcemia -
• 10% to 20% of all cancer patients
• Lung and breast tumors - most common primaries.
• Secondary to increased bone turnover and increased calcium reabsorption.
• immobilization and dehydration - contributing factors
• secretion of a parathyroid-related protein as well as secretion of cytokines (TGF-β, IL-1,
TNF)
• Treatment - IV fluid rehydration and bisphosphonates
• can result in cardiac/kidney dysfunction, and even death in extreme cases.
19. Coagulation abnormalities
• from metastatic tumor spread to the liver
• D/t toxic side effects of chemotherapeutic agents
• frequent blood transfusions - antiplatelet antibodies
• Thrombocytopenia - from diffuse bone marrow replacement or wide field irradiation
• Heparin- induced thrombocytopenia (HIT) - heparin should be stopped.
• Treatment for coagulopathies depends primarily on the underlying cause.
20. DVT
• immobility
• solid tumors release cytokines - procoagulant effects
• prophylaxis with pneumatic compression boots and subcutaneous heparin - helpful in
decreasing the rate of postoperative DVT.
• routinely perform Doppler ultrasound screening prior to surgery.
• preoperative DVT - managed with inferior vena cava filter placement.
• Postoperatively, DVTs - treated with either inferior vena cava filters or anticoagulation.
22. Chemotherapy
• Relatively limited role in the treatment of spinal metastases.
• Role in the treatment of chemosensitive tumors - neuroblastoma, Ewing sarcoma
(PNET), osteogenic sarcoma, germ cell tumors, and lymphoma.
• Chemotherapy is considered the primary treatment for patients with these tumors
even in the presence of epidural compression.
• Chemotherapy and hormones may be useful in the treatment of prostate and breast
carcinoma, but local therapy with radiation or surgery is commonly used for
symptomatic metastases
23. Steroids
• Indications:
1. oncolytic - multiple myeloma and lymphoma.
2. control of biologic pain.
3. control of vasogenic edema
• In patients fully ambulatory without spinal cord compression, steroids may not be
needed.
• undiagnosed spinal mass - steroids should be withheld prior to biopsy( oncolytic
effect of on certain tumors, such as lymphoma and thymoma).
• Patients with high-grade spinal cord compression and myelopathy in whom a delay in
steroid administration may affect the neurologic outcome.
24. Bisphosphonates
• inhibit osteoclast activity and thus reduce or inhibit further bone resorption
• do not promote the deposition of new bone.
• Their use can decrease the rate of pathologic fractures, compression fractures,
hypercalcemia, and the need for radiation to bone metastases in patients with breast
cancer and multiple myeloma.
25. Spinal metastasis with unknown primary
• uncommon.
• They are defined as a biopsy-proven histological malignancy demonstrating a cancer that could
not have originated at the biopsy site, and for which no identifiable primary site of tumor could
be found.
• Incidence: 0.4% to 38%
• Urgent PET-CT
• Tissue for histology should be obtained before starting the treatment.
• postpone corticosteroids until after the biopsy
• Unstable spine - immediate stabilizing surgery.
• median survival from diagnosis of 15.8 months
27. N - Neurolologic assessment
O - Oncologic assessment
M - Mechanical assessment
S - Systemic assessment
28. NEUROLOGIC ASSESSMENT
• six-point grading system designed and validated by the Spine Oncology Study Group
(SOSG) to describe the degree of Epidural Spinal Cord Compression (ESCC).
• This system uses axial T2-weighted images at the site of most severe compression
31. • Grades 0, 1a, and 1b - radiation as initial treatment (In the absence of
mechanical instability)
• Grades 2 and 3 (high-grade ESCC) - surgical decompression prior to
radiation therapy (unless the tumor is highly radiosensitive).
• Grade 1c - The role of surgery and radiosurgery is illdefined, but the
integration of high-dose hypofractionated radiation may allow
administration of SRS while avoiding spinal cord toxicity.
33. Radiosensitive Tumors
• Patients with radiosensitive tumors - be treated with cEBRT regardless of the ESCC
grade.
• Has been shown to improve ambulatory status, provide durable local tumor control,
and provide pain relief.
34. Radioresistant Tumors Without High-Grade ESCC
• Radioresistant tumors and ESCC grades 0, 1a, and 1b - to be treated with IGRT and do
not require surgical decompression.
• limitation of cEBRT - Delivering tumoricidal doses of radiation to radioresistant tumors
without high risk of spinal cord or adjacent organ
• responses of greater than 85% regardless of tumor histology.
• SRS - better first-line treatment than the extensive surgical intervention
35. SRS
• can deliver high doses of radiation in close proximity to the spinal cord while maintaining
radiation exposure of the spinal cord and other adjacent vital structures within the limits of
safety.
• The benefits of primary - shorter treatment time, which minimizes the potential for interruptions
in systemic therapy, delivery of a high radiobiologic dose, which may overcome the relative
radioresistance that challenged conventional radiotherapy in certain histologies.
• Relies on IGRT platforms and can be administered as a single fraction or in 3–5 fractions using
a hypofractionated schedule.
• COMPLICATIONS - esophagitis, mucositis, dysphagia, diarrhea, paresthesia, transient
laryngitis, delayed vertebral fractures and transient radiculitis, radiation-induced spinal cord
injury
36.
37. Radioresistant Tumors With High-Grade ESCC
• require surgical decompression and stabilization prior to IGRT.
• Prospective randomized trial conducted by Patchell et al. showed that surgical
decompression followed by cEBRT yielded significantly superior results when
compared to cEBRT alone.
• ‘Separation surgery’ - to provide separation between the tumor and the spinal cord
and permit optimal SRS dosing to the tumor.
• Postoperative SRS - provides durable local tumor control rates, similar to the results
of SRS treatment for low- grade ESCC tumors.
38. Separation surgery
• The term “separation surgery” was devised by Benzel and Angelov to describe such operations, in which
only minimal tumor resection is carried out to separate the tumor margin from the spinal cord, leaving the
bulk of the tumor mass to be treated with radiation.
• The goal of separation surgery is to provide a distance between the tumor and the spinal cord and does
not include aggressive tumor resection in order to optimize cytoreduction.
• The separation required between the tumor and the spinal cord is 2 to 3 mm.
• Separation surgery achieves this goal using a posterior approach, laminectomy, a transpedicular
approach to the ventral epidural space, sectioning of the posterior longitudinal ligament, and removal of
the ventral epidural tumor without significant vertebral body resection followed by posterolateral
instrumented stabilization.
• Combining separation surgery with effective postoperative SRS provides excellent local tumor control.
• Reported 1-year local control after separation surgery followed by single-fraction SRS was 91% and
when followed by high-dose hypofractionated SRS was 96%.
39. SRS as an adjuvant treatment
• Currently, tumor resection is less aggressive and aimed at epidural decompression
and instrumentation to provide stabilization (separation surgery).
• Anterior corpectomy procedures in certain cases can be successfully avoided by
posterior decompression and instrumentation alone followed by SRS to the remaining
anterior lesion.
• Benefit of SRS - lack of soft tissue injury.
• Reexploration after SRS often shows no signs of fibrosis, in contra-distinction to the
situation after cEBRT
• offered in the early postoperative period, as early as 1 week after open surgery.
40.
41. Spine oncology study group’s recommendations:
indications for spine SRS:
(1) primary definitive therapy for previously unirradiated tumors,
(2) salvage radiosurgery for recurrent or progressive tumors having failed prior cEBRT,
(3) postoperative radio-surgery after surgical intervention with or without spinal
stabilization.
42. SRS - Failure
• The interface between the tumor and the spinal cord is frequently underdosed relative
to the target to keep the dose to the spinal cord within a safe limit.
• The consequence of failure at this interface is disease progression and tumor
recurrence.
• This is most true in cases of repeat irradiation.
• Also, in the setting of spinal instrumentation where artifact formation often
compromises imaging quality.
• To overcome limitations in image quality, CT myelography may improve accurate
delineation of this interface.
43. SRS in the setting of re-irradiation
• A great advantage of spine SRS is the ability to reirradiate patients after failed cEBRT
within spinal cord tolerance.
• Surgical intervention is limited by concerns of radiation-induced hypoxia and fibrosis,
which potentially impairs wound healing
• reirradiation using conventional techniques is limited by concerns of spinal cord
tolerance and potential risks of late spinal cord myelopathy.
44. • The combination of neurologic and oncologic assessments can help one decide whether
the patient may undergo immediate radiation or if surgical decompression is required.
• Only those patients harboring radioresistant tumors with high-grade ESCC require surgical
intervention prior to radiation therapy.
• Radiation therapy provides all other patients with adequate local tumor control, pain
control and maintenance or recovery of neurologic function.
• Surgery can be avoided in these patients unless there is progression of tumor or
neurologic deficit during radiation, prior external beam radiation to overlapping ports, or
spinal instability.
• The type of radiation offered depends on tumor histology, with the use of cEBRT for
radiosensitive tumors and SRS for radioresistant histologies.
Summary
45. MECHANICAL ASSESSMENT
• Mechanical instability - independent indication for surgical stabilization or percutaneous
cement augmentation, regardless of the ESCC grade and radiosensitivity of the tumor.
• Radiation - has no impact on spinal stability.
• The SOSG has defined SPINAL INSTABILITY as the “loss of spinal integrity as a result of a
neoplastic process that is associated with movement-related pain, symptomatic or progressive
deformity, and/or neural compromise under physiologic loads”
• The assessment of spinal instability is dependent on both clinical and radiographic criteria.
• Clinically, patients with spinal instability present with severe movement-related pain that is
characteristic of the specific spinal level involved.
• Instability pain must be distinguished from biologic pain.
46. Spinal Instability Neoplastic Score (SINS)
• SINS (0 – 6) - do not require surgical stabilization
• SINS (13–18) - need for surgical stabilization
• SINS (7-12) - require further assessment to determine
the need for surgery.
47. MIS
• Patients with substantial posterior involvement of spinal elements - unlikely to get pain relief
from surgery alone.
• In patients with anterior vertebral body and posterior facet joint involvement, both
percutaneous cement augmentation and pedicle screw fixation might be beneficial.
• Minimal invasive surgical techniques including percutaneous vertebroplasty (PVP),
percutaneous kyphoplasty (PKP), radiofrequency ablation (RFA), cryoablation, and
transarterial embolization
48. Percutaneous vertebroplasty and kyphoplasty
• important tools for the management of pathologic fractures.
• They are MIS OPD procedures
• contraindications: uncorrected coagulopathy, spinal canal
compromise of more than 20% of the diameter, radiculopathy,
and severe vertebral body collapse (defined as more than
75% collapse).
• Vertebroplasty might also be used to augment the strength of
the constructs.
• should be considered especially in patients with poor bone
quality, such as those with multiple myeloma.
49. SYSTEMIC ASSESSMENT
• All treatment decisions are predicated on the patient’s ability to tolerate the proposed
intervention based on the extent of systemic comorbidities and tumor burden.
• Metastatic spine invasion by certain tumor histologies is indicative of shortened survival
and may preclude benefit from some interventions.
• Numerous prognostic scoring systems exist to facilitate the estimation of the expected
survival of patients with spinal metastases.
• Surgery serves a palliative purpose - concentrate on whether the patients would have an
opportunity to adequately recover from the indicated surgery and/or radiation in order to
continue systemic therapy.
53. Surgical treatment
• Usually the type of metastatic tumor that will cause epidural compression arises anteriorly to
the spinal cord and progresses posteriorly.
• Cervical spine - accessed anteriorly more easily than posteriorly (anterior decompression
followed by posterior instrumentation).
• Thoracic spine - anterior surgical approaches becomes significantly more difficult.
• T1 to T4 - challenging due to their anatomic relation with the sternum, and a sternotomy or
thoracotomy might be necessary to decompress the spinal cord from an anterior approach.
• T5 - T10 have a close anatomic relation with important vascular structures such as the aortic
arch and the great vessels. Anterolateral approach - a right-sided thoracotomy is
recommended.
54. • The remaining thoracolumbar junction can be approached through a posterior or a
combined 360-degree approach, including a thoracotomy or retroperitoneal
approaches.
• The L1-5 levels can be easily accessed via a retroperitoneal or transabdominal
approach.
• Sacral lesions commonly require a more complex posterior approach or anteriorly
through the pelvis.
