Background: Genetic Risks: Li-Fraumeni syndrome (p53) NF1 (malignant peripheral nerve sheath tumors) Familial Rb Gardeners/FAP (APC) Desmoid tumors Most are sporadic tumors Risk factors: Prior radiation is the #1 risk factor (esp within 10-30 years) HIV or HHV-8 (Kaposi Sarcoma) Chronic Lymphedema (Angiosarcoma) Most common types: Gastrointestinal stromal tumor (GIST) Characterized by c-KIT or PDGFRA mutations Liposarcoma Well-differentiated/Dedifferentiated liposarcoma MDM2