How fast does sarcoma grow?

Rate of growth depends on the site and type of sarcoma

Sarcoma has to be treated by surgical excision if it is in the early stage / local disease. If it is not removed surgically, it can spread to local surrounding organs or other organs. 

Sarcoma is a connective tissue tumor mainly. It is of different histological origin like from bones, muscles , cartilage etc. The rate of growth of tumor size also depends on the tumor grade and biological behavior. You need to show the reports to oncologist and Imaging on regular intervals to assess the growth rate

Usually sarcomas grow aggressively. Exact type of sarcoma, stage at diagnosis & previous treatment details are required to comment

Sarcomas are wide variety of soft tissue/bone tumors. Few can be very slow growing over many years (Like low grade sarcomas), whereas few are very fast growing (Like pleomorphic sarcomas, osteosarcomas).

The growth rate of sarcomas depends on the grade. A low grade sarcoma is a slow growing Tumor which may take even an year to reach 5cm or less. On the other hand, a high grade sarcoma not only increases rapidly in size, it can also spread to other organs, like lung, very fast