Radiation Oncology: A Question-Based Review

Cord Compression

Bronwyn R. Stall and Kevin Camphausen

image Background

What % of cancer pts develop cord compression?

5%–10% of cancer pts develop cord compression.

What are 3 routes of metastatic spread to the spine?

Routes of metastatic spread to the spine: hematogenous, direct extension, and CSF. (Abeloff MD et al., Abeloff's clinical oncology. 4th ed. 2008)

What malignancies commonly cause cord compression?

Cancers that commonly cause cord compression include lung, breast, prostate, renal cell, lymphoma, and multiple myeloma.

How do pts with cord compression present?

Presenting Sx of cord compression: back pain, radicular pain, weakness, altered sensation, bowel/bladder dysfunction, and paralysis

What is the most common presenting Sx of cord compression?

The most common Sx of cord compression is back pain.

What part of the vertebra is most commonly involved by metastatic Dz?

Metastatic Dz typically involves the vertebral body rather than the post elements.

What part of the spine is most often involved in cord compression?

The thoracic spine is most commonly affected by cord compression.

image Workup/Staging

Describe the workup of cord compression.

Cord compression workup: H&P with careful −attention to complete neurologic exam, evaluation of sensation to determine level of the lesion, assessment of pain, assessment of bowel/bladder function, and screening MRI spine

Why is a screening MRI of the spine ordered to evaluate cord compression?

Pts with suspected cord compression should be −evaluated with a screening MRI of the spine b/c −multilevel involvement is not uncommon.

Why is CT useful in evaluating cord compression?

CT evaluation of spinal cord compression helps to delineate osseous structures, including retropulsed fragments, and aids in surgical planning.

image Treatment/Prognosis

What modalities are used to treat spinal cord compression?

Modalities used to treat spinal cord compression: −steroids, surgery, and RT

What is the initial management of cord compression?

For initial management of cord compression, start −steroids and consult neurosurgery or orthopedics, depending on the institution, to assess spine stability.

What initial bolus dose of steroids should be used in cord compression?

For newly diagnosed cord compression, a loading dose of 10 mg intravenously is generally given → 4 mg orally q6hrs. Vecht et al. randomized 37 pts to 10 mg intravenously vs. 100 mg intravenously, both → 16 mg daily in divided oral doses. There was no difference in pain control, rate of ambulation, or bladder function. (Neurology 1989)

Historically, what type of surgery was used to treat spinal cord compression?

Historically, laminectomy was used to treat spinal cord compression. However, this was abandoned b/c it can lead to instability, and improved surgical stabilization techniques have allowed for ant decompressive approaches.

What pts with cord compression are appropriate for decompressive surgery?

Pts with MRI evidence of cord compression in a single area and a life expectancy >3 mos who do not have radiosensitive tumors (lymphomas, leukemias, germ cell tumors, multiple myeloma) may be good candidates for decompressive surgery → RT. (Patchell R et al., Lancet 2005)

What was the trial design and outcome of the Patchell study of decompressive surgery for cord compression?

The Patchell cord compression trial was a multi-institutional RCT of 101 pts with MRI-confirmed spinal cord compression restricted to a single area with >3-mo life expectancy. Exclusion criteria included being paraplegic >48 hrs, radiosensitive tumors, Hx of prior cord compression, and other pre-existing neurologic conditions. Pts were randomized to decompressive surgery + RT vs. RT alone. RT was 30 Gy/10 delivered to the lesion + 1 vertebral body above and below. Surgery was tailored to the individual lesion to provide circumferential decompression and stabilization as needed. The study was stopped at interim analysis. Surgery significantly improved the ambulatory rate (84% vs. 57%), duration of ambulatory status (122 days vs. 13 days), and survival (122 days vs. 100 days). Pts nonambulatory prior to Tx were more likely to walk after surgery (62% vs. 19%). (Patchell R et al., Lancet 2005)

What data support the use of SRS for spinal mets?

Prospective nonrandomized data from the University of Pittsburgh support the use of SRS for spinal mets. 500 cases were treated with CyberKnife to a median dose of 20 Gy. SRS improved pain in 86% of cases (defined as a 3-point improvement on a 10-point pain scale). The majority of pts had prior Tx; however, in the 65 cases treated with SRS as the primary modality, the LC was 90%. (Gerstzen P et al., Spine 2007)

What pts with cord compression should be treated with RT alone?

Cord compression pts treated with RT alone: life expectancy <3 mos, no spinal instability or bony compression, and radiosensitive tumor

How are conventional RT fields arranged to treat the cervical, thoracic, and lumbar spine?

Field arrangement for cord compression:

1.     Cervical: opposed lats

2.     Thoracic: AP/PA or PA alone, respecting cord tolerance

3.     Lumbar: AP/PA

4.     Encompass the lesion + 1–2 vertebral levels above and below.

What fractionation schemes are used for cord compression?

Fractionation in cord compression: typically 300 × 10, but consider hypofractionation (400 × 5) in debilitated pts; protracted regimens such as 40/20 or 37.5/15 may be used in pts with a longer life expectancy.

image Toxicity

What are potential acute toxicities of RT for cord compression?

Potential toxicities of RT for cord compression: odynophagia, globus, esophagitis, nausea, diarrhea, myelosuppression, rare spinal cord injury