Trial of Carbon Ion Versus Photon Radiotherapy for Locally Advanced, Unresectable Pancreatic Cancer

To compare the efficacy of carbon ion-based chemo radiotherapy with x-ray-based chemo radiotherapy for the treatment of locally advanced pancreatic adenocarcinoma by comparison of overall survival at 2 years following treatment. Patient has 2 in 3 chance of receiving Arm A and 1 in 3 chance of receiving Arm B. Arm A (chemoradiation takes place in Japan): CIRT in 12 fractions/treatments plus concurrent gemcitabine, followed by 4 cycles of gemcitabine + nab-Paclitaxel, or until progression or intolerance of therapy Arm B: IMRT in 28 fractions plus concurrent gemcitabine or capecitabine, followed by 4 cycles of gemcitabine + nab-Paclitaxel, or until progression or intolerance of therapy Per investigator discretion, patients may receive either: 1. Definitive treatment : 2. Neoadjuvant treatment: Adjuvant chemotherapy 4 cycles of gemcitabine/nab-paclitaxel or FOLFIRNOX, Gemcitabine alone if these regimens are unavailable