Review of metastatic spine tumour classification and indications for surgery: the consensus statement of the Global Spine Tumour Study Group

Abstract

Choosing the right operation for metastatic spinal tumours is often difficult, and depends on many factors, including life expectancy and the balance of the risk of surgery against the likelihood of improving quality of life. Several prognostic scores have been devised to help the clinician decide the most appropriate course of action, but there still remains controversy over how to choose the best option; more often the decision is influenced by habit, belief and subjective experience. The purpose of this article is to review the present systems available for classifying spinal metastases, how these classifications can be used to help surgical planning, discuss surgical outcomes, and make suggestions for future research. It is important for spinal surgeons to reach a consensus regarding the classification of spinal metastases and surgical strategies. The authors of this article constitute the Global Spine Tumour Study Group: an international group of spinal surgeons who are dedicated to studying the techniques and outcomes of surgery for spinal tumours, to build on the existing evidence base for the surgical treatment of spinal tumours.

Fig. 1

Schematic diagram of the surgical classification of spinal tumours, from Tomita et al. [7] (with permission of Lippincott Williams and Wilkin)

Fig. 2

The Enneking classification of primary tumour staging. Benign tumours are classified as stages I, II and III, depending on the tumour growth and aggressiveness (1 tumour capsule, 2 adjacent tissue reaction). Malignant tumours are classified as IA, IB, IIA and IIB depending on degree of spread (1 tumour capsule, 2 tissue reaction, 3 island of tumour within adjacent tissue reaction, 4 skip metastasis) [36] (with permission of Lippincott Williams and Wilkin)

Fig. 3

Weinstein, Boriani, Biagini (WBB) classification describes the vertebral involvement as sections of a clock face (“zones”) centred on the spinal cord, from zone 1 (left spinous process and lamina) through zone 6 (left anterior wedge of vertebral body) and back round to zone 12 (right spinous process and lamina). In addition, the prefixes A–E are used to denote radial levels (“layers”) of vertebral involvement, from extraosseous paraspinal tissues (layerA) through to extradural (layer D) and intradural (layer E) [37] (with permission of Lippincott Williams and Wilkin)

Fig. 4

Page snapshot of the Global Spine Tumour Study Group prospective database for metastatic tumour surgery. Preoperative data entry

Fig. 5

Classification of surgical strategies, as determined by the Global Spine Tumour Study Group