The abstract from the study "Tumor vascularization and histopathologic regression of soft tissue sarcomas treated with isolated limb perfusion with TNF-α and melphalan" is available here:
http://www.ncbi.nlm.nih.gov/pubmed/21400518
According to the study, synovial sarcomas were poor responders. Nevertheless, I should mention that one of our member (Charbonnel) had this done on his leg and responded well enough. The surgeon could easily remove the tumor afterward and amputation was not necessary...