This system stratifies RPS patients into three risk groups according to tumor histology, with “Atypical lipomatous tumor” (ALT, well-differentiated liposarcoma) having the best prognosis, “non-ALT liposarcoma” (non-ALT LPS) having the worst overall survival and “Other” histology (non-LPS) having an intermediate prognosis. Here, GPT is linked to liposarcoma.