Bone Tumor Staging Systems

Author: Patrick O'Donnell

Topic updated on 03/12/13 10:14am

Introduction

Prognosis of bone cancer depends on the following variables
1. overall stage of disease (incorperates all of the below)
2. presence of metastasis
3. skip (discontinous) lesions within the same bone
4. histologic grade
5. tumor size
The are two staging systems that are commonly used:
- MSTS or Enneking System
- AJCC Staging System

MSTS (Enneking) Staging System

Introduction
- most popular and useful for orthopaedic surgeons
- two systems - one for malignant lesions and one for benign lesions
  - malignant lesions are defined using Roman numerals (e.g. I, II, III)
    - see table below
    - e.g. osteosarcoma most commonly presents as stage IIB
  - benign lesions are defined using Arabic numbers (1,2,3)
    - 1 = latent lesion
      - e.g. non-ossifying fibroma
      - enchondroma
    - 2 = active lesion
      - e.g. ABC, UBC
      - chondromyxoid fibroma
      - chondroblastoma
    - 3 = aggressive lesion
      - e.g. giant cell tumor of bone

Stage	Grade	Site (1)	Metastasis
IA	Low Grade	T1 - intracompartmental	M0 (none)
IB	Low Grade	T2 - extracompartmental	M0 (none)
IIA	High Grade	T1 - intracompartmental	M0 (none)
IIB	High Grade	T2 - extracompartmental	M0 (none)
III	Metastatic	T1 - intracompartmental	M1 (regional or distant)
III	Metastatic	T2 - extracompartmental	M1 (regional or distant)

Tumor Compartments
- intracompartmental
  - bone tumors are confined within the cortex of the bone
- extracompartmental
  - bone tumors extend beyond the bone cortex
Tumor Grade
- histologically, tumors are graded based on the percentage of cellular atypia
  - low grade tumors
    - low metastatic potential
    - e.g. parosteal osteosarcoma
  - high grade tumors
    - greater metastastatic potential
    - e.g. intramedullary osteosarcoma, Ewing's sarcoma, dedifferentiated chondrosarcoma

AJCC Staging System

Stage	Grade	Size	Depth	Node	Metastasis	5 yr. survival
IA	Low Grade	< 8cm	any	none	none	98%
IB	Low Grade	> 8cm			none
IIA	High Grade	< 8cm	any	none	none	82%
IIB	High Grade	> 8cm	superficial	none	none	82%
III	any	discontinuous (skip) lesion	deep	none	none	52%
IVA	any	any		none	lung
IVB	any	any	any	present	other than lung	30%

Prognosis for soft tissue tumors depends on
- grade
  - low grade: G1 and G2
  - high grade: G3 and G4
- size
  - T1: < 8 cm
  - T2 > 8 cm
- nodes
  - N0: no regional nodes
  - N1: regional nodes
- metastasis
  - presence of distant metastasis automatically elevates patient to stage IV disease

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(OBQ05.7) A 13-year-old girl presents with an isolated distal femur osteosarcoma that extends into the soft tissue. Work-up is negative for metastasis, but biopsy reveals a high grade lesion. What is the stage of this tumor by the Musculoskeletal Tumor Society system? Topic

Review Topic

1. I A
2. II A
3. I B
4. II B
5. III

PREFERRED RESPONSE ▶

DISCUSSION: This patient has a osteosarcoma that is high grade, extracompartment, and without metastases, so it is a IIB by the MSTS Staging System. This is the most common MSTS stage for a osteosarcoma to present. Here is a review of the stages in the MSTS (Enneking) Staging System:
(I-A = Low Grade, intracompartmental, No Metastases);
(I-B = Low Grade, extracompartment, No Metastases);
(II-A = High Grade, intracompartmental, No Metastases);
(II-B = High Grade, extracompartment, No Metastases);
(III = Any Grade, Distant Metastases).

REFERENCES:

2. AJCC Cancer Staging Manual, ed. 6. 2002. pp. 213-19.

3. Enneking WF. A system of staging musculoskeletal neoplasms. Clin Orthop Relat Res. 1986 Mar;(204):9-24. PMID:3456859 (Link to Abstract)

Question Authors:

Patrick O'Donnell MD/PhD, Derek Moore,

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ABOS II: Bone Tumor Staging Systems

General - Oral Boards Review

7/29/2011

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Textbooks

Review of Orthopaedics, 6th Edition, Mark D. Miller MD, Stephen R. Thompson MBBS MEd FRCSC, Jennifer Hart MPAS PA-C ATC, an imprint of Elsevier, Philadelphia, Copyright 2012
AAOS Comprehensive Orthopaedic Review, Jay R. Leiberman. Published by American Academy of Orthopaedic Surgeons, Rosemont IL. Copyright 2009
Orthopaedic Knowledge Update 10, John M Flyn. Published by American Academy of Orthopaedic Surgeons, Rosemont IL. Copyright 2011
Hoppenfeld SP. Surgical Exposures in Orthopaedics: The Anatomic Approach. Lipponcott, Williams, and Wilkins, Philadelphia, PA, Copyright 2009
Orthopaedic In-training Examination (OITE) Questions 2004-2012, American Academy of Orthopaedic Surgeons, Rosemont IL. Copyright 2004-2012
Self-Assessment Examination (SAE) Questions 2004-2012, American Academy of Orthopaedic Surgeons, Rosemont IL. Copyright 2004-2012

Undefined

Orthopaedic Knowledge Update: Musculoskeletal Tumors. Menendez LR (Editor). Published by American Academy of Orthopaedic Surgeon, Rosemont, IL. Copyright 2002
AJCC Cancer Staging Manual, ed. 6. 2002. pp. 213-19.
Enneking WF. A system of staging musculoskeletal neoplasms. Clin Orthop Relat Res. 1986 Mar;(204):9-24. PMID:3456859 (Link to Abstract)

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Bone Tumor Staging Systems

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