Primary and Metastatic Tumors of the Spine: Total En Bloc Spondylectomy

Hideki Murakami

Norio Kawahara

Katsuro Tomita

BACKGROUND

Conventionally, curettage or piecemeal excision has been the usual approach to vertebral tumors.
These approaches have clear disadvantages, however, including high risk of tumor cell contamination to the surrounding structures and residual tumor tissue at the site due to difficulty in demarcating tumor from healthy tissue.
These contribute to incomplete resection of the tumor as well as high local recurrence rates of the spinal malignant tumor.
To reduce local recurrence and to increase survival, we have developed total en bloc spondylectomy (TES).¹⁰,¹¹,¹⁴
In this method, the entire vertebra or vertebrae containing the malignant tumor are resected, together with en bloc laminectomy, en bloc corpectomy, and bilateral pediculotomy using a T-saw through the posterior approach.⁹
Using this technique, we are able to excise the tumor mass together with a wide or marginal margin.

ANATOMY

The following tissues serve as barriers to spinal tumor progression: the anterior longitudinal ligament (ALL), the posterior longitudinal ligament (PLL), the periosteum abutting the spinal canal, the ligamentum flavum (LF), the periosteum of the lamina and spinous process, the interspinous ligament (ISL), the supraspinous ligament (SSL), the cartilaginous endplate, and the cartilaginous annulus fibrosus. However, both the PLL and the periosteum on the lateral side of the vertebral body are “weak” anatomic barriers. In contrast, the ALL, cartilaginous endplate, and annulus fibrosus are “strong” barriers. In the spine, one vertebra could be regarded as a single oncologic compartment and the surrounding tissues as barriers to tumor spread (FIG 1).⁵

FIG 1 • Compartment and barrier. SSL, supraspinous ligament; LF, ligamentum flavum; PLL, posterior longitudinal ligament; ALL, anterior longitudinal ligament; CL, capsular ligament; ISL, interspinous ligament.

INDICATIONS

Surgical indication for primary tumors
- The surgical strategy for primary spinal tumors used at the authors’ institution is based on Enneking’s concept of musculoskeletal tumors³ (Table 1).
Surgical indication for metastatic tumors
- Surgical strategy for spinal metastases (Table 2) consists of three prognostic factors¹²:
  - Grade of malignancy
  - Visceral metastases
  - Bone metastases
- The extent of the spinal metastases is stratified using the surgical classification of spinal tumors (Table 3), and technically appropriate and feasible surgery is employed, such as en bloc spondylectomy, piecemeal thorough excision, curettage, or palliative surgery.

Table 1 Surgical Strategy for Primary Spinal Tumors

Surgical Staging	Contamination/Residual Tumor	Surgical Margin	Spinal Cord Salvage Surgery
Benign tumor
1. Latent			Don’t touch!
2. Active	OK/OK	Intralesional	Debulking (piecemeal)
3. Aggressive	No/no	Intralesional or marginal	Thorough excision (piecemeal/en bloc)
Malignant tumor
I. Low grade	No/no
II. High grade	No/no	Marginal or wide	Total en bloc excision
III. With metastases	No/no	(Radical: impractical)

Table 2 Surgical Strategy for Spinal Metastases


Table 2 Appendix Points for Each Primary Tumor
1	point = slow growth	4	points = rapid growth
	Breast cancer^*		Lung cancer
	Thyroid cancer^*		Gastric cancer, esophageal cancer
	Prostatic cancer, testicular cancer		Nasopharyngeal cancer
2	points = moderate growth		Hepatocellular cancer
	Renal cell cancer^*		Pancreas cancer, etc.
	Uterus cancer, ovarian cancer		Bladder cancer
	Colorectal cancer		Melanoma
			Sarcoma (osteosarcoma, Ewing sarcoma, leiomyosarcoma, etc.)
			Primary unknown metastasis
			Other rare cancers
			… etc.
^*Rare types of the following cancers should be given 4 points as rapidly growing cancers: breast cancer, inflammatory type; thyroid cancer, undifferentiated type; renal cell cancer, inflammatory type.

Table 3 Surgical Classification of Spinal Tumors

Intracompartmental	Extracompartmental	Multiple
Type 1 Vertebral body	Type 4 Spinal canal extension	Type 7
Type 2 Pedicle extension	Type 5 Paravertebral extension
Type 3 Body – lamina extension	Type 6 Adjacent vertebral extension