Accurate diagnosis is essential to successful treatment of bone cancer. The wrong kind of biopsy may make it more difficult later for the surgeon to remove all of the cancer without having to also remove all or part of the arm or leg. A biopsy that is not done correctly may cause the cancer to spread. It is very important for the biopsy procedure to be performed by a surgeon with experience in diagnosing and treating bone tumors as well as limb salvage techniques.
If your doctor thinks you may have bone cancer, it’s important to go to a cancer center with a specialized bone cancer program. You should look for a program that does as many diagnostic procedures as possible.
If you have symptoms that may signal bone cancer, your doctor will examine you and ask you questions about your health and your family history. One or more of the following tests may be used to find out if you have cancer and if it has spread. These tests also may be used to find out if treatment is working.
A biopsy, which removes a tiny piece of bone, is used to confirm the presence of cancer cells. This is the only way to find out for certain if the tumor is cancer or another bone disease. It is very important for the biopsy procedure to be done by a surgeon with experience in diagnosing and treating bone tumors.
There are two types of bone biopsy:
Needle biopsy: A long, hollow needle is inserted through the skin to the area of bone to be tested. The needle removes a cylindrical sample of bone to look at under a microscope.
Open or surgical biopsy: An incision (cut) is made, and the surgeon removes a tiny piece of bone for examination under a microscope.
Your doctor will decide which type of biopsy is best for you based on several factors, including the type and location of the tumor. If possible, the surgeon who performs the biopsy should also do the surgery to remove the cancer.
If you are diagnosed with bone cancer, your doctor will determine the stage (or extent) of the disease. Staging is a way of determining how much disease is in the body and where it has spread.
This information is important because it helps your doctor determine the best type of treatment for you and the outlook for your recovery (prognosis). Once the staging classification is determined, it stays the same even if treatment is successful or the cancer spreads.
AJCC Staging System
(source: National Cancer Institute)
One system that is used to stage all bone cancer is the American Joint Commission on Cancer (AJCC) system.
- T stands for features of tumor (its size)
- N stands for spread to lymph nodes
- M is for metastasis (spread) to distant organs
- G is for the grade of the tumor
This information about the tumor, lymph nodes, metastasis and grade is combined in a process called stage grouping.
The stage is then described in Roman numerals from I to IV (1-4).
T stages of bone cancer
- TX: Primary tumor can't be measured
- T0: No evidence of the tumor
- T1: Tumor is 8 centimeters (around 3 inches) or less
- T2: Tumor is larger than 8 centimeters
- T3: Tumor is in more than one place on the same bone
N stages of bone cancer
- N0: The cancer has not spread to the lymph nodes near the tumor
- N1: The cancer has spread to nearby lymph nodes
M stages of bone cancer
- M0: The cancer has not spread anywhere outside of the bone or nearby lymph nodes
- M1: Distant metastasis (the cancer has spread)
- M1a: The cancer has spread only to the lung
- M1b: The cancer has spread to other sites (like the brain, the liver, etc)
Grades of bone cancer
- G1-G2: Low grade
- G3-G4: High grade
TNM stage grouping
After the T, N and M stages and the grade of the bone cancer have been determined, the information is combined and expressed as an overall stage. The process of assigning a stage number is called stage grouping.
To determine the grouped stage of a cancer using the AJCC system, find the stage number below that contains the T, N and M stages, and the proper grade.
Stage I: All stage I tumors are low grade and have not yet spread outside of the bone.
- Stage IA: T1, N0, M0, G1-G2: The tumor is 8 centimeters or less.
- Stage IB: T2 or T3, N0, M0, G1-G2: The tumor is either larger than 8 centimeters or it is in more than one place on the same bone.
Stage II: Stage II tumors have not spread outside the bone (like stage I) but are high grade.
- Stage IIA: T1, N0, M0, G3-G4: The tumor is 8 centimeters or less.
- Stage IIB: T2, N0, M0, G3-G4: The tumor is larger than 8 centimeters.
Stage III: T3, N0, M0, G3-G4: Stage III tumors have not spread outside the bone but are in more than one place on the same bone. They are high grade.
Stage IV: Stage IV tumors have spread outside of the bone they started in. They can be any grade.
- Stage IVA: Any T, N0, M1a, G1-G4: The tumor has spread to the lung.
- Stage IVB: Any T, N1, any M, G1-G4 OR Any T, any N, M1b, G1-G4: The tumor has spread to nearby lymph nodes or to distant sites other than the lung (or both).
Even though the AJCC staging system is widely accepted and used for most cancers, bone cancer specialists tend to simplify the stages into localized and metastatic. Localized includes stages I, II and III, while metastatic is stage IV.