DNA mutations in soft tissue sarcoma are common. But they're usually acquired during life rather than having been inherited before birth. Acquired mutations may result from exposure to radiation or cancer-causing chemicals. In most sarcomas, they occur for no apparent reason.

How do sarcomas start?

Sarcoma starts when certain cells, like muscle cells, grow out of control and crowd out normal cells. This makes it hard for the body to work the way it should. Sarcoma cells can spread to other parts of the body. Sarcoma cells in an arm muscle can sometimes travel to the lung and grow there.

Where does sarcoma come from?

Sarcoma is a rare cancer that starts in connective tissues such as bone, cartilage, and muscle. It develops when the cells that make up these tissues (called mesenchymal cells) begin to grow out of control. Some types of sarcoma are found in children, while others are more common in adults.