Chemoradiotherapy With Gemcitabine/S-1 vs Gemcitabine/S-1 for Locally Advanced Pancreatic Cancer

Inclusion Criteria: 1. Histologically or cytologically confirmed adenocarcinoma, adenocarcinoma squamous carcinoma of pancreatic cancer. 2. Patients who confirmed unresectable locally advanced pancreatic cancer with the criteria below. * Involving over 1/2 circumference of major artery (SMA/CA). (Under 1/2 that was borderline lesion.) * Involving over the merging section of portal-SMV. * No distal metastasis with diagnostic imaging. * Confirmed by CT image performed with in four weeks before registration. 3. Performance Status:0-1(ECOG) 4. Patients of age =\>20 and 80\> 5. sufficient organ functions * neutrophils\>=1,500/mm3 * platelets\>=100,000/mm3 * hemoglobin\>=9.0g/dl * AST(GOT)/ALT(GPT) \<=150IU * total bilirubin \<=2.0mg/dl, (or \<=3.0mg/dl if biliary drainage were present) * serum creatinine \<= 1.2mg/dl * creatinine clearance\>=60ml/min 6. Life expectancy more than 3 months. 7. Written informed consent. Exclusion Criteria: 1. Lung fibrosis or intestinal pneumonia, and anamnesis or imaging findings. 2. Watery diarrhea 3. Severe infection 4. Severe complication (heart failure, renal failure, hepatic insufficiency,hemorrhagic peptic ulcer, intestines paralysis,ileus or uncontrolled diabetes etc) 5. Massive pleural or abdominal effusion. 6. Metastasis to central nervous system. 7. Active synchronous or metachronous malignancy other than carcinoma in situ. 8. Regular use of flucytosine, fenitoin or warfarin 9. Pregnant or lactation women, or women with known or suspected pregnancy and men who want let to pregnancy 10. Severe mental illness 11. Patients who are judged inappropriate for the entry into the study by the investigator.