Staging is a way of describing or classifying a cancer based on the extent of the cancer, or where it is in the body. Doctors may use the simple staging system or the Enneking staging system. The child’s healthcare team uses the stage to plan treatment and estimate prognosis.
Doctors often use a simple system to stage childhood bone cancer. It groups bone cancers as localized and metastatic.
Localized bone cancer is only in the bone that it started in and tissues next to the bone, such as muscle, tendons or fat.
Metastatic bone cancer has spread to other parts of the body farther from the original tumour. For example, it may have spread to the lungs or other bones not directly connected to the bone where the tumour started. The most common place for bone cancer to spread to is the lungs.
The Enneking staging system is another staging system used for osteosarcoma. It may also be called the Musculoskeletal Tumor Society, or MSTS, staging system. It is based on the grade of the tumour, whether or not the tumour has grown through the wall of the bone and whether or not it has spread. Because all cancerous bone tumours in children are high grade, it is never diagnosed as stage I.
The cancer is high grade and is only inside the bone.
The cancer is high grade and has grown though the bone wall into other nearby structures. Most osteosarcomas are diagnosed as this stage.
The cancer is either inside the bone or grown through the bone into nearby structures. The cancer has spread to other parts of the body or to other bones far away from where the cancer started.
Recurrent bone cancer means that the cancer has come back after it has been treated. If it comes back in the same place that the cancer first started, it’s called local recurrence. If it comes back in tissues or lymph nodes close to the primary tumour, it’s called regional recurrence. It can also recur in another part of the body, which is called metastatic bone cancer.
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