Usually with Sarcoma in the limbs, they amputate the limb where the Sarcoma is...

There are 200 + types of Sarcoma, so maybe radiation and chemotherapy could be an option.
What I have learned in my 6 + months of research on Sarcoma, is that if it's caught early enough, it cannot be allowed to spread (Metastasize), as the risk becomes so great that it will spread into the soft tissue behind your lungs or your lungs itself, or to your vertebrae... All of which are untreatable areas and cause complications with other bodily organs and functions...

Sarcoma needs to be treated with unprecedent setting intensity !!!

If you were lucky enough to catch it very early and lucky enough that it is not a high grade Sarcoma with the ability to grow right back, you better find a Doctor that truly knows Sarcoma and can at least treat it and give you some sort of additional life expectancy, otherwise the prognosis is not very good at all, and unfortunately your life expectancy is minimal at best...