Tissue Effects after Stereotactic Body Radiotherapy using Cyberknife for Patients with Abdominal Malignancies

Aims: To report the tissue effects of treatment with single fraction stereotactic body radiotherapy (SBRT) using Cyberknife on malignant tumours of the abdomen and adjacent normal organs. Materials and methods: The data from four autopsies with unresectable pancreatic carcinoma and one lymph node excision from a case of recurrent neuroblastoma were reviewed for radiation-related tissue effects within the primary cancer and the normal organs within the radiation field. Results: Cases of unresectable pancreatic carcinoma consistently showed radiation-induced changes in both the primary tumour and the adjacent, non-malignant colorectal tissue. An additional case of lymph nodes exposed to stereotactic radiation showed typical radiation-related changes, including lymphocyte depletion and capsular fibrosis. Conclusions: A myriad of radiation-related tissue effects are seen after SBRT with Cyberknife. The changes parallel those reported after conventionally fractionated radiotherapy and suggest that the pathophysiological mechanisms of radiation-induced normal tissue damage are similar for biologically equivalent single and fractionated doses of radiotherapy.