FIBROMYXOID SARCOMA...radiation or not????

I have been diagnosed with low grade fibromyxoid sarcoma in my left thigh. It has been there for 16 years and is very large (6 inches). Because of its size (I assume) one specialist wants to do radiation prior to removal. The other specialist says that radiation prior to removal may turn low grade to high grade and just wants to remove it and do no radiation at all unless there is high grade cells found in it or he could not get clear enough margins. Does anyone have experience with this or an opinion? I am really confused and becoming highly stressed trying to decide the best plan of attack.