Introduction Two mechanisms of action production of free radicals direct genetic damage Indications Indications of external beam irradiation definitive control (primary malignant bone tumors) Ewing sarcoma/primative neuroectodermal tumor primary lymphoma of bone hemangioendothelioma solitary plasmacytoma of bone adjuvant to surgical excision soft tissue sarcomas may be given pre or post-operatively as adjuvant to surgical excision no difference exists in overall survival and the timing of radiation palliative care and impending fracture fixation metastatic bone disease needed after fixation of impending/pathologic fractures to reduce overall tumor burden prostate tumors are very radiosensitive breast cancer is 70% sensitive, 30% resistant GI and renal tumors are not radiosensitive Technique 1 rad = 1 centiGray Typical dose is 180-200 cGy/day radiation is given in "fractions" as radiotherapy is cumulative the total dose of therapy is the summation of all the separate fractions given during treatment Total dose < 45 Gray: usually leads to uncomplicated tissue healing 45 - 55 Gray: tissue usually heals but with problems > 60 Gray: tissue unlikely to heal Preoperative vs. Postoperative Preoperative vs. Postoperative Radiation Preoperative RT (neoadjuvant) Postoperative RT (adjuvant) Wound complications More wound complications (up to 40%) Less wound complications (<20%) Edema, fibrosis, joint stiffness Less (<15%) More edema, fibrosis, joint stiffness (>20%) (usually temporary) Radiation field Smaller field Larger field Pseudocapsule Allows formation of pseudocapsule to facilitate close-margin resection No pseudocapsule advantage Tumor shrinkage Helps shrink tumor prior to surgery No tumor shrinkage advantage Local recurrence Lower local recurrence rates Higher local recurrence rates Complications Soft tissue complications early effects delayed wound healing infection desquamation late effects fibrosis joint stiffness secondary sarcoma (below) fractures (below) Post-radiation sarcoma defined by the development of a sarcoma in a region previously radiated for malignancy incidence is ~13% more frequent in patients with prior chemotherapy overal patient prognosis is very poor Post-radiation fractures approximately 25% incidence following soft tissue sarcoma resection and external beam irradiation risk factors for post radiation fracture radiation dose ≥ 59Gy weight bearing bones esp. femur female volume of bone receiving it anterior femoral compartment resection age periosteal stripping some advocate prophylactic fixation if periosteal stripping is performed osteoporosis