An endoscopic ultrasonography-guided interstitial brachytherapy based special treatment-planning system for unresectable pancreatic cancer.

EUS-guided interstitial brachytherapy is promising in the treatment of unresectable malignant carcinoma adjacent to the digestive tract. The feasible treatment plan is not established. Thus, our study aimed to develop a novel treatment plan and evaluate the feasibility in patients with unresectable pancreatic cancer. A total of 42 patients with unresectable pancreatic cancer (stage III: n = 18; stage IV: n = 24) were retrospectively included. A special treatment-planning system (TPS) for EUS was designed and evaluated by comparing with the traditional TPS. The patients underwent EUS-guided interstitial brachytherapy based on the new software. In the test model, there was no obvious difference of irradiation doses calculated by the two softwares (EUS TPS vs. traditional TPS) ( P > 0.05). Under the support of EUS TPS, a novel treatment plan for EUS-guided interstitial brachytherapy was successfully established, which contained seven principles. All patients tolerated the treatment well without any serious complications. In 15 patients (stage III) whose minimal peripheral dose was larger than 90 Gy, partial remission rate was 80% (12/15). Twelve patients (12/18) in stage III were alive for over 12 months with a median peripheral dose of 107.5 Gy. The expected median survival time of the 42 patients was 9.0 months (95%CI 7.6-10.4 months). The results demonstrated that the new EUS TPS will play an important role in EUS-guided interstitial brachytherapy in patients with unresectable pancreatic malignant cancer.