Carbon Ion RT for Locally Advanced Pancreatic Cancer

Inclusion Criteria: * Histologically or cytologically proven diagnosis of adenocarcinoma of the pancreas * Sum of maximum diameters of tumor and involved lymph nodes ≤6 cm T1-4N0-1M0, * Unresectable disease by radiographic criteria (pancreas protocol CT or MRI) or surgical exploration within 30 days prior to registration, defined based on at least one of the following: major venous thrombosis of the portal vein or SMV extending for several centimeters (precluding vein resection and reconstruction) encasement (\>180°) of the SMA or proximal hepatic artery abutment of the celiac trunk * No evidence of distant metastases, based upon axial (PET, CT, or MRI) imaging of the chest, abdomen, and pelvis within 30 days prior to registration * ECOG Performance Status 0-1 within 30 days prior to registration * Age ≥ 18 * CBC/differential obtained within 14 days prior to step 1 registration, with adequate bone marrow function defined as follows: * Absolute neutrophil count (ANC) ≥ 1,500 cells/mm3 * Platelets ≥ 100,000 cells/mm3 * Hemoglobin ≥ 9.0 g/dl (NOTE: The use of transfusion or other intervention to achieve Hgb ≥ 9.0 g/dl is acceptable) * Additional laboratory studies within 14 days prior to registration demonstrating: Creatinine \< 2 mg/dl; GFR \> 50 mL/min (Cockroft and Gault formula) * Bilirubin \< 1.5 x ULN * ALT and AST ≤ 2.5 x ULN * aPTT, PT ≤ 1.5 x ULN * Patients must provide study specific informed consent prior to study entry. * Women of childbearing potential and male participants must practice adequate contraception during protocol treatment and for at least 6 months following treatment For females of child-bearing potential, negative serum pregnancy test within 30 days prior to registration Exclusion Criteria: * More than one primary lesion * Tumor invasion of the duodenum or stomach, confirmed by upper endoscopy * Active malignancy, other than pancreatic cancer, for which systemic therapy is indicated. -History of adequately treated local basal cell or squamous cell carcinoma of the skin, cervical carcinoma in situ, superficial bladder cancer, asymptomatic prostate cancer without known metastatic disease and with no requirement for therapy asides from hormonal therapy, adequately treated stage 1or 2 cancer currently in complete remission, or any other cancer that has been in complete remission for ≥ 5 years is permitted. * Prior treatment for pancreatic cancer with surgical resection, external radiotherapy, or interstitial isotope implantation. * Prior treatment for pancreatic cancer with a systemic therapy regimen/agent not included in the list below. Systemic therapy must be discontinued at least 14 days before study enrollment. * FOLFIRINOX * Gemcitabine/nab-paclitaxel * Gemcitabine * S-1 * Prior radiation therapy to the abdomen that would result in overlap of radiation therapy fields