<prompt> Most common malignant tumour of bone is:Osteogenic sarcomaChondro sarcomaEwings sarcomaMetastasis  <response>: Metastatic bone disease 224-M 193-Apleys 8thMetastatic bone disease - In patients over 50 years bone metastasis are seen more frequently than all primary malignant bone tumours. Commonest source is carcinoma of breast, next in frequency are prostate, kidney, lung, thyroid, bladder and GIT Commonest sites for bone metastasis are -vertebrae pelvis the proximal half of the femur and the humerus Spread is usually via the blood stream. 