Abstract: Objective  To investigate the risk factors and patterns of radiation induced gastroduodenal complications in patients with pancreatic cancer following tomotherapy (TOMO) using endoscopy. Methods  Patients with pancreatic cancer who were treated TOMO in Air Force General Hospital from February 2010 to May 2015 were collected. All patients underwent endoscopic examination before and after radiotherapy. The radiation injuries were observed, and factors influencing radiationinduced gastroduodenal complications were analyzed. Results  The median time of gastroscopy after radiotherapy was 1 month, radiation gastritis and duodenitis were 41 cases (58.6%), radiation gastric and duodenal ulcers were 30 cases (42.9%), and hemorrhage 7 cases (10.0%), scar formation 3 cases (4.3%), 6 cases (8.6%) had newly developed gastric retention, and 4 cases (5.7%) had newly developed gastric varix. Univariate analysis showed that relieving jaundice and radiation protection (amifostine) were associated with the development of radiation gastric ulcers (χ²=4.186, P=0.041; χ²=5.679, P=0.017). Conmon terminology criteria for adverse events (CTCAE)≥2 was associated with the development of radiation duodenal ulcers (χ²=3.960， P=0.047). Mean dose (Dmean) ＞13.39 Gy and Dmean≤13.39 Gy gastric ulcers rates were 25.0% and 9.1%, respectively (AUC=0.740, P=0.048). Conclusion  The TOMO induced gastroduodenal injury in patients with pancreatic cancer is frequent. Relieving jaundice is the protection of radiation gastric ulcer. Dmean＞13.39 Gy is independent predictive factors for radiation gastric ulcers. Patients after TOMO should be examined by endoscopy early.

Key words: Pancreatic neoplasms, Radiotherapy, Gastroscopy, Peptic ulcer, Factor analysis, statistical