Abstract: Objective To investigate the clinical effect of CyberKnife radiosurgery in locally advanced pancreatic cancer or pancreatic cancer with distant metastasis.Methods A retrospective analysis was performed for the clinical data of 32 patients with pancreatic cancer who were treated with CyberKnife radiosurgery in The Fifth Medical Center of Chinese PLA General Hospital from January 2012 to April 2015, among whom 9 patients received arterial infusion chemotherapy in addition.Among these 32 patients, 18 had locally advanced pancreatic cancer and 14 had pancreatic cancer with distant metastasis (12 had liver metastasis, 2 had lung metastasis, and 2 had bone metastasis) .Radiological evaluation was performed every two months after treatment;Response Evaluation Criteria in Solid Tumors (RECIST) was used to evaluate local remission rate;CT-based radiological examination was used to assess the presence or absence of tumor progression;Common Terminology Criteria for Adverse Events Version 3.0 (CTCAE3.0) was used to analyze adverse events.The Kaplan-Meier method was used to calculate overall survival time and local progression-free survival, and the log-rank test was used for the comparison of overall survival time between groups.Results Of all 32 patients, 21 had lesions in the head of the pancreas and 11 had lesions in the body and tail of the pancreas;according to pathology, 30 had adenocarcinoma and 2 had other pathological types;according to TNM staging, 25 had T3 and 7 had T4 pancreatic cancer, 23 had N0 and 9 had N1 pancreatic cancer, 18 had M0 and 14 had M1 pancreatic cancer.Among the 9 patients who were treated with CyberKnife combined with arterial infusion chemotherapy, 5 received chemotherapy via the gastroduodenal artery, 1 received chemotherapy via the superior mesenteric artery, and 3 received chemotherapy via the splenic artery.Of all 32 patients, 4 (12.50%) achieved complete remission, 18 (56.25%) achieved partial remission, 6 (18.75%) achieved a stable disease, and 4 (12.50%) experienced disease progression.The1-and 2-year overall survival rates were 43.7%and 31.3%, respectively;the 1-and 2-year local progression-free survival rates were87.5%and 84.4%, respectively;the median overall survival time was 8.5 months (range 1-39 months) .The 18 patients with locally advanced pancreatic cancer had a median overall survival time of 21 months (range 1-36 months) , and the 14 patients with pancreatic cancer with distant metastasis had a median overall survival time of 5.5 months (range 1-39 months) , and there was no significant difference between the two groups (P=0.303) .The 9 patients who received arterial infusion chemotherapy in addition to CyberKnife had a median overall survival time of 17 months (range 1-39 months) , and the 23 patients who received CyberKnife alone had a median overall survival time of 8 months (range 1-36 months) , and there was no significant difference between the two groups (P=0.756) .The incidence rate of grade 1-2 acute and late gastrointestinal toxicity was 78%, with major symptoms of nausea, vomiting, abdominal pain, and diarrhea.One patient experienced grade 3 late gastrointestinal toxicity manifesting as duodenal ulcer bleeding, and the bleeding was stopped by emergency intervention with a coil to block the target blood vessel.Among the 20 patients with abdominal pain or lower back pain, 12 achieved marked alleviation of pain symptoms at 2 weeks after treatment.Conclusion CyberKnife radiosurgery has a good clinical effect in the treatment of locally advanced pancreatic cancer or pancreatic cancer with distant metastasis and has few complications.