Bone Cancer Stages

After someone is diagnosed with bone cancer, doctors will try to figure out if it has spread, and if so, how far. This process is called staging. The stage of a cancer describes how much cancer is in the body. It helps determine how serious the cancer is and how best to treat it. Doctors also use a cancer's stage when talking about survival statistics.

Bone cancers range from stages I (1) through IV (4). As a rule, the lower the number, the less the cancer has spread. A higher number, such as stage IV, means cancer has spread more. And within a stage, an earlier letter means a lower stage. Although each person’s cancer experience is unique, cancers with similar stages tend to have a similar outlook and are often treated in much the same way. 

How is the stage determined?

The staging system most often used for bone cancer is the American Joint Committee on Cancer (AJCC) TNM system, which is based on 4 key pieces of information:

  • The extent (size) of the tumor (T): How large is the cancer? Is it in more than one spot in the bone?
  • The spread to nearby lymph nodes (N): Has the cancer spread to nearby lymph nodes?
  • The spread (metastasis) to distant sites (M): Has the cancer spread to the lungs only or to distant sites such as other bones or the liver?
  • The grade of the cancer (G): How abnormal do the cells look when seen under a microscope?

The scale used for grading bone cancer is from 1 to 3. Low-grade cancers (G1) tend to grow and spread more slowly than high-grade (G2 or G3) cancers.

  • Grade 1 (G1) means the cancer looks much like normal bone tissue.
  • Grade 3 (G3) means the cancer looks very abnormal.
  • Grade 2 (G2) falls somewhere in between.

The staging system described below is the most recent AJCC system effective January 2018 and applies to bone cancers of the appendicular skeleton (such as bones in the arms and legs), trunk, skull, and facial bones. Bone cancers of the pelvis and spine use different T categories and it is best to speak with your doctor about your stage for these specific cancers.

Numbers or letters after T, N, and M provide more details about each of these factors. Higher numbers mean the cancer is more advanced. Once a person’s T, N, and M categories have been determined, this information is combined in a process called stage grouping to assign an overall stage. For more information see Cancer Staging.

The staging system in the table below uses the pathologic stage (also called the surgical stage). It is determined by examining tissue removed during an operation. Sometimes, if surgery is not possible right away or at all, the cancer will be given a clinical stage instead. This is based on the results of a physical exam, biopsy, and imaging tests. The clinical stage will be used to help plan treatment. Sometimes, though, the cancer has spread further than the clinical stage estimates, and may not predict the patient’s outlook as accurately as a pathologic stage.

Cancer staging can be complex, so ask your doctor to explain it to you in a way you understand. 

AJCC Stage

Stage grouping

Stage description*

IA

T1

N0

M0

G1 or GX

The cancer is 8 centimeters (cm) across (about 3 inches) or smaller(T1). It has not spread to nearby lymph nodes (N0) or to distant sites (M0). The cancer is low grade (G1) or the grade cannot be determined (GX).

 

 

IB

T2

N0

M0

G1 or GX

The cancer is larger than 8 cm (3 inches) across (T2). It has not spread to nearby lymph nodes (N0) or to distant sites (M0). The cancer is low grade (G1) or the grade cannot be determined (GX).

OR

T3

N0

M0

G1 or GX

The cancer is in more than one place on the same bone (T3). It has not spread to nearby lymph nodes (N0) or to distant sites (M0). The cancer is low grade (G1) or the grade cannot be determined (GX).

IIA

 

T1

N0

M0

G2 or G3

The cancer is 8 centimeters (cm) across (about 3 inches) or less (T1). It has not spread to nearby lymph nodes (N0) or to distant sites (M0). The cancer is high grade (G2 or G3).

IIB

 

T2

N0

M0

G2 or G3

The cancer is larger than 8 cm (3 inches) across (T2). It has not spread to nearby lymph nodes (N0) or to distant sites (M0). The cancer is high grade (G2 or G3).

III

T3

N0

M0

G2 or G3

The cancer is in more than one place on the same bone (T3). It has not spread to nearby lymph nodes (N0) or to distant sites (M0). The cancer is high grade (G2 or G3).

IVA

Any T

N0

M1a

Any G

The cancer can be any size and may be in more than one place in the bone (Any T) AND has not spread to nearby lymph nodes (N0). It has spread only to the lungs (M1a). The cancer can be any grade (Any G).

IVB

Any T

N1

Any M

Any G

The cancer can be any size and may be in more than one place in the bone (Any T) AND it has spread to nearby lymph nodes (N1). It may or may not have has spread to distant organs like the lungs or other bones (Any M). The cancer can be any grade (Any G).

OR

Any T

Any N

M1b

Any G

The cancer can be any size and may be in more than one place in the bone (Any T) and it might or might not have spread to nearby lymph nodes (Any N). It has spread to distant sites like other bones, the liver or brain (M1b). The cancer can be any grade (Any G).


* The following additional categories are not listed on the table above:

  • TX: Main tumor cannot be assessed due to lack of information.
  • T0: No evidence of a primary tumor.
  • NX: Regional lymph nodes cannot be assessed due to lack of information. 

The American Cancer Society medical and editorial content team
Our team is made up of doctors and master’s-prepared nurses with deep knowledge of cancer care as well as journalists, editors, and translators with extensive experience in medical writing.

Last Medical Review: December 8, 2017 Last Revised: December 8, 2017

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