Sarcomas are a group of many cancerous tumors that develop from cells derived from the body’s supporting tissue.

It could be :

tumors of “soft tissues” (adipose tissue, muscles, vessels … but also viscera: stomach, colon, etc.)
or tumors of the “hard” parts (bones and cartilages) of the body.
They can be located in very different places of the body.

There are at least 50 kinds, of very different types and molecular characteristics.