A bone tumor is an abnormal growth of tissue in bone, traditionally classified as noncancerous (benign) or cancerous (malignant). Cancerous bone tumors usually originate from a cancer in another part of the body such as from lung, breast, thyroid, kidney and prostate. There may be a lump, pain, or neurological signs from pressure. A bone tumor might present with a pathologic fracture. Other symptoms may include fatigue, fever, weight loss, anemia and nausea. Sometimes there are no symptoms and the tumour is found when investigating another problem.

Diagnosis is generally by X-ray and other radiological tests such as CT scan, MRI, PET scan and bone scintigraphy. Blood tests might include a complete blood count, inflammatory markers, serum electrophoresis, PSA, kidney function and liver function. Urine may be tested for Bence Jones protein. For confirmation of diagnosis, a biopsy for histological evaluation might be required.

The most common bone tumor is a non-ossifying fibroma. Average five-year survival in the United States after being diagnosed with bone and joint cancer is 67%. The earliest known bone tumor was an osteosarcoma in a foot bone discovered in South Africa, between 1.6 and 1.8 million years ago.