Bone Tumours
Primary bone tumours are rare and predominantly affect younger patients. Multidisciplinary management at a specialist centre is a consistent theme in how they are discussed.
Disease categories
Major disease categories
- Osteosarcoma
- Ewing sarcoma
- Chondrosarcoma
- Chordoma
- Giant cell tumour of bone
Molecular
Molecular considerations
EWSR1 fusions define Ewing sarcoma. IDH1 and IDH2 alterations occur in chondrosarcoma. Brachyury expression characterises chordoma. H3F3A alteration is described in giant cell tumour of bone.
Markers commonly discussed in bone tumours
- EWSR1 fusions
- IDH1 / IDH2
- Brachyury
- H3F3A
- MDM2 / CDK4
Not exhaustive, and not every marker is assessed in every patient. Which of these is relevant depends on the individual case and should be discussed with the treating team.
Testing
Genomic testing considerations
Fusion and marker testing directed by the suspected entity.
Germline
Germline considerations
Li-Fraumeni syndrome and retinoblastoma predisposition are considered in osteosarcoma, particularly in young patients.
Molecular monitoring
ctDNA and liquid biopsy considerations
Investigational.
Single-cell & computation
Single-cell and algorithmic approaches
Single-cell analysis in sarcoma is used to characterise differentiation state and the stromal and immune compartments, both of which vary widely across a group of more than a hundred entities. Single-cell DNA sequencing contributes to clonal structure questions in tumours that are frequently heterogeneous. Algorithm work centres on fusion detection and breakpoint characterisation — the defining event in many sarcoma subtypes — together with methylation-based classification for diagnostically difficult cases.
Decisions
Treatment decision questions
Questions worth raising with a treating team when a decision is being made:
- Has specialist bone pathology review been obtained?
- Has the appropriate molecular confirmation been performed?
Resistance
Resistance and recurrence questions
- Has the diagnosis been reviewed where behaviour is atypical?
Trials
Clinical trial considerations
Trials are concentrated at specialist centres.
When a precision oncology review may help
A review is most useful where the standard pathway has been exhausted or where the picture is more complicated than a protocol accounts for — rare presentations, treatment resistance, complex or apparently contradictory molecular findings, or a decision between several defensible options.
The output is a structured analysis and a set of questions for the treating team. It is not treatment, and it does not replace the treating oncologist.