Radiotherapy in Musculoskeletal Tumours

Radiotherapy kills tumour cells by causing DNA damage, and tumours vary greatly in how sensitive they are. RADIOSENSITIVE musculoskeletal tumours include Ewing sarcoma, lymphoma and myeloma of bone, and metastases (treated palliatively), so RT has a major therapeutic role in these. RADIORESISTANT tumours - notably osteosarcoma and chondrosarcoma - are managed primarily by surgery (with chemotherapy for osteosarcoma), and RT is reserved for unresectable or palliative situations. Understanding this spectrum determines whether RT is curative-intent, an adjunct to surgery, or palliative.

For high-grade, large or deep soft-tissue sarcoma, the combination of wide local excision and radiotherapy achieves local control comparable to amputation while preserving the limb. RT can be given:

• Neoadjuvant (pre-operative): a smaller field and lower dose, which can downsize the tumour and reduce late effects, but at the cost of more acute wound-healing complications and dehiscence (so some centres delay surgery several weeks after RT).
• Adjuvant (post-operative): a larger field and higher dose, with more late fibrosis, joint stiffness and oedema/lymphoedema. Local control is similar between the two; the choice balances early wound morbidity against late functional morbidity. RT is generally indicated for high-grade or large/deep tumours and for close/positive margins.

• Ewing sarcoma: radiosensitive - RT gives local control when surgery is not feasible or margins are inadequate, integrated with chemotherapy.
• Bone lymphoma and solitary plasmacytoma/myeloma: very radiosensitive and frequently treated with RT.
• Osteosarcoma/chondrosarcoma: radioresistant - surgery is the mainstay (RT palliative/unresectable only).
• Bone metastases: palliative RT relieves pain, is given after internal fixation of an impending/ pathological fracture, and treats metastatic spinal cord compression (with or without surgery).
• Modalities: external-beam RT (conventional/IMRT), brachytherapy, SBRT, and proton-beam therapy (e.g. for chordoma and spinal tumours, to spare the spinal cord).