Symptoms of soft tissue sarcoma depend on where the tumour is in the body. The most common symptoms are: 

• a growing lump under the skin, often on an arm or a leg – this may be either painless or painful 
• pain 
• trouble breathing. 

Symptoms of bone sarcoma include: 

• for osteosarcoma, swelling over a bone, or pain, stiffness or tenderness in a bone or joint 
• for Ewing sarcoma, fever for no known reason, or pain, swelling or a lump in the area of the tumour, such as the arms, legs, chest, back or pelvis – the lump is often soft and feels warm 
• a bone that breaks for no known reason. 

Symptoms of gastrointestinal stromal tumour (GIST) can include: 

• blood in the stools or vomit 
• abdominal pain 
• swelling or lump in the abdomen 
• feeling bloated 
• loss of appetite, and feeling full quickly 
• feeling very tired 
• difficulty or pain when swallowing (if the tumour is in the oesophagus). 

GIST may not cause any symptoms until the tumours reach a certain size. Very small tumours are common, and some of these will not grow or spread. 

There are several conditions that may cause these symptoms, not just sarcoma. If you have any of these symptoms, you should discuss them with your doctor.