Postoperative radiation therapy

Radiation therapy can also be given postoperatively. In general, radiation is indicated for patients with inadequate surgical margins and for larger, high-grade tumors.[32,33] This is particularly important in high-grade tumors with tumor margins smaller than 1 cm.[34,35]; [36][Level of evidence C3] With combined R0 (negative margin) surgery and radiation therapy, local control of the primary tumor can be achieved in about 90% of patients with extremity sarcomas, 70% to 75% of patients with retroperitoneal sarcomas, and 80% of patients overall.[21,37-40]

Retroperitoneal sarcomas are unique in that the radiosensitivity of the bowel increases the risk of injury and makes postoperative radiation therapy less desirable.[41,42] Postoperative adhesions and bowel immobility can increase the risk of damage from any given radiation dose. This contrasts with the preoperative approach in which the tumor often displaces bowel outside of the radiation field, and any exposed bowel is more mobile, which decreases exposure to specific bowel segments.