Compared with conventional radiation, a single-fraction dose and total dose of target volume can be increased in stereotactic body radiation therapy (SBRT). In addition, doses of organs at risk would be reduced, thus effectively improving local control rates and reducing radiation related toxicity. Shorter course of SBRT also enhance patients' compliance and render the initial of other treatment on schedule possible. Pollom et al. demonstrated that no significant differences were found in six-month and one-year overall survival rates between single-fraction SBRT and multi-fraction SBRT. However, potential trends indicated prolonged overall survivals in patients receiving multifractions. Moreover, the incidence of gastrointestinal toxicity is higher in single-fraction SBRT due to higher doses. Therefore, multi-fraction SBRT is more common in pancreatic cancer treatment. To the best of our knowledge, there are few studies on pancreatic cancer SBRT treatment, and these studies are retrospective with small patient population. Therefore, the investigators propose to conduct a phase II study: five-fraction SBRT as the initial treatment for locally advanced pancreatic cancer. Whether patients would receive thereafter treatment, including chemotherapy of surgeries, depends on their medical conditions.