Causes

It's not clear what causes osteosarcoma. Doctors know this cancer forms when something goes wrong in one of the cells that are responsible for making new bone.

Osteosarcoma begins when a healthy bone cell develops changes in its DNA. A cell's DNA contains the instructions that tell a cell what to do. The changes tell the cell to start making new bone when it isn't needed. The result is a mass (tumor) of poorly formed bone cells that can invade and destroy healthy body tissue. Cells can break away and spread (metastasize) throughout the body.