chronic disease of middle age, characterized by excessive breakdown and formation of bone tissue. The disease is common among people of northern European descent; it is almost nonexistent among people of Asian and African descent. The disease leads to deformities, fractures (fracture), and arthritis and may cause an increased risk of cancer, particularly osteosarcoma. The long bones, vertebrae, pelvis, and skull are most commonly affected, in men more often than in women. In the bone-destructive stages, bones soften and blood supply to the area increases, which may lead to heart or circulatory problems. In bone-constructive stages, bones are dense and brittle and fracture easily. Treatment includes the administration of medications such as biphosphonates or calcitonin, which inhibit bone cell activity. Individuals with Paget disease of bone should also exercise regularly and receive adequate daily amounts of calcium and vitamin D. The disease is named for the English surgeon and pathologist Sir James Paget (Paget, Sir James, 1st Baronet), who first described it.