Staging is the process of finding out if and how far the cancer has spread. The treatment and outlook for survival depend mostly on the stage of the cancer.

As a rule, doctors (especially those treating children) divide osteosarcomas into 2 "stages" -- localized and metastatic -- when deciding on the best course of treatment.

Localized: A localized osteosarcoma affects only the bone it started in and the tissues next to the bone, such as muscles and tendons.

Metastatic: A metastatic osteosarcoma has spread to other parts of the body not directly connected to the bone the tumor started in. Most often the spread is to the lungs, but it can also spread to other bones, the brain, or other organs.

Patients with metastases at the time the cancer is found have a worse outlook, although some can be cured if the metastases can be removed by surgery. The cure rate for these patients is greatly improved if chemo is also given.

Enneking staging system

The system most often used to formally stage this cancer is known as the Enneking system. It takes into account the grade of the tumor, how large the first tumor is, and whether or not the cancer has spread to nearby lymph nodes or other organs. The grade is found by looking at the cancer cells under a microscope and is used to predict how likely they are to grow and spread.

These factors are combined to give an overall stage, expressed in Roman numerals from I to III (1 to 3). Each of these stages is also subdivided into A or B. In general, the higher the number, the more serious the cancer.

AJCC staging system

A second staging system, the AJCC system, divides osteosarcoma into 4 stages using Roman numerals I to IV (1 to 4).

Ask your doctor to explain the stage of your (or your child's) cancer to you in terms you can understand.

Last Medical Review: 03/20/2007
Last Revised: 03/20/2007