Bone Tumor Staging – Malignant & Benign

When reading about bone tumors online or discussing them with a professional in person, you’ll hear them talk about the tumors in stages or grades. Unfortunately, most patients and their loved ones aren’t familiar with the differences between the stages and what they actually mean. In this blog, we’d like to remove that fog and transparently discuss the staging systems we use at Greater Dallas Orthopaedics.

Benign bone tumor staging and malignant bone tumor staging are actually quite different, so we’ll be discussing them separately. As always, this is no substitute for medical advice and is not intended to inform self-diagnosis. If you or a loved one believe they may have a bone tumor, seek medical attention at the earliest convenience.

Benign Bone Tumor Staging

For benign bone tumors, we utilize the Enneking surgical staging system. This system doesn’t classify skull tumors or marrow-originating tumors but it is widely used by orthopedic surgeons due to its compartment-based classification.

These grades go from least severe to most severe.

Grade 1

The tumor is latent or inactive. This patient has no symptoms. Their tumor is not growing and their x-rays are consistent with a benign process. Typically, the tumors do not require treatment and will be observed annually to monitor any changes.

Grade 2

The tumor is benign but is growing and causing symptoms to appear. There is no overt bone destruction and treatment will typically consist of minimally-invasive surgery to remove the tumor and place a bone graft in its place.

Grade 3

The tumor has destroyed some amount of bone and must be removed by excision of the area. Oftentimes, these tumors are locally aggressive and have the potential to return even after the aggressive local treatment has been completed.

Malignant Bone Tumor Staging

For malignant bone tumors, most orthopedic surgeons use the MSTS, or Musculoskeletal Tumor Society, staging system. The lower grade tumors shown here are less aggressive and have less ability to metastasize compared to their high-grade counterparts. 
These stages go from least severe to most severe.

Stage I A

These are low-grade malignant tumors that are confined to the bone and shown virtually no sign of potential metastasis.

Stage I B

These are low-grade malignant tumors that exist in the bone but also have some soft tissue mass. These are highly unlikely to metastasize.

Stage II A

These are high-grade malignant tumors that are confined to the bone, showing some signs of potential metastasis, though it is still unlikely.

Stage II B

These are high-grade malignant tumors that exist in the bone but also have some soft tissue mass. They have a small chance of metastasis, but it’s highly unlikely.

Stage III

These malignant tumors are unique in that they can be either low- or high-grade, and can be confined to a bone or can include some soft tissue mass. The consistent through-line of Stage III malignant bone tumors is that they have metastasized somewhere in the body.

We sincerely hope this blog helped to shed some light on the grading and staging nomenclature used by orthopedic surgeons. While it can be confusing for patients and their loved ones, these stages do help to inform surgeons and their decisions.

In a future Greater Dallas Orthopaedics blog, we’ll discuss the grading and staging of soft tissue tumors, both malignant and benign.