Malignant (cancerous) tumors of the chest wall can start in muscles, bones, cartilage, blood vessels, connective or fatty tissue, nerves, or skin of the chest. Tumors found in the chest wall may be malignant or benign. They are described as being primary tumors, which start in the chest wall, or metastatic tumors, which spread to the chest wall from cancer in other areas of the body. The most common type of primary chest wall tumors are sarcomas that begin in bone or muscle tissue.