Pancreatic cancer is one of the most lethal malignant tumors, probably attributable to local recurrence deemed as a predominant factor influencing patients' prognosis and quality of life. Only 15%-20% patients are suitable for surgeries among those first diagnosed with pancreatic cancer and the 5-year survival rate of those patients with R0 resection is still less than 20%. Therefore, radiotherapy is becoming a promising method to improve survival. However, due to adjacent organs at risk, conventional external beam radiotherapy, besides long courses, sometimes results in severe radiation-induced toxicity, delaying the initial of thereafter treatment, such as chemotherapy, which reduces clinical benefits.~A single-fraction dose in the gross tumor volume could be increased stereotactic body radiotherapy (SBRT). Furthermore, doses of organs at risk could also be reduced, thus effectively improving local control rates and reducing radiation related toxicity. Compared with conventional external beam radiotherapy, SBRT is proved to provide longer progression free survival and safe with combination of chemotherapy. Moreover, owing to short courses and low toxicity of SBRT, quality of life is largely improved.~However, it was reported that progression usually occurred 2 years after the initial treatment. The most common failure pattern was local recurrence. Chemotherapy and supportive treatment were commonly used in relapsed pancreatic cancer but with unfavored outcomes. Palliative surgeries are performed in patients with recurrent pancreatic cancer in some studies. Nevertheless, because of bad medical conditions and high complication rates, many patients could not endure surgeries. Therefore, whether patients previously treated with SBRT could be re-irradiated is another challenge in the treatment of pancreatic cancer.~Some studies have confirmed that improved quality of life and longer survival could be available with re-irradiation via SBRT in patients with relapsed pancreatic cancer. Real-time guiding and synchronous tracing of SBRT increase the doses of tumor volumes but decrease doses of organs at risk and toxicity, rendering SBRT as an alternative treatment for relapsed pancreatic cancer. Chris et al. demonstrated that 1-year local control rate was 70% after re-irradiation with SBRT in 14 patients and the toxicity was mild. Nergiz Dagoglu et al. showed that the median overall survival was 14 months and no grade 3, 4 and 5 toxicities occurred.~From 2013-2015, we retrospectively reviewed medical records of 14 patients with relapsed pancreatic cancer re-irradiated with SBRT. All of their tumor markers and pain scores decreased and quality of life improved 3 months after re-irradiation. Hence, based on our experience, we attempt to prospectively evaluate the safety and efficacy of re-irradiation with SBRT for relapsed pancreatic cancer.
The safety and efficacy of re-irradiation with stereotactic body radiotherapy for relapsed pancreatic cancer will be evaluated.