The primary objective of this study is to compare tumor response rate of the test arm(gemcitabine+S-1) with the control arm(gemcitabine alone) in patients with unresectable pancreatic cancer

Pancreatic cancer is the fifth leading cause of cancer death in the United States. It is difficult to diagnose at its early stage and only 10-20% of patients are candidates for resection with 5-year survival rate of less than 10%. Patients with unresectable pancreatic cancer has a poor prognosis. Gemcitabine, a cytidine analogue, is the standard chemotherapeutic agent for the disease with median survival time(MST) ranging from 6 to 8 months. Phase Ⅲ study showed that combinations with other drugs, such as oxaliplatine or CDDP, did not contribute to survival time. TS-1, a new oral fluoropyrimidine which consists of the 5-FU prodrug tegafur (ftorafur, FT) and two enzyme inhibitors, CDHP (5-chloro-2,4-dihydroxypyridine) and OXO (potassium oxonate), in a molar ratio of 1(FT):0.4 (CDHP):1(OXO), is commercially available since late 90'in Japan. Phase II trials have demonstrated that S-1 was effective as a single agent for treatment of gastric (RR 44.6%), colorectal (RR 37.4%), head and neck, breast, non-small cell lung, and pancreatic cancers(20%). A combination of gemcitabine and TS-1 is found to be effective and promising in phase Ⅱ trial for metastatic pancreatic carcinoma in selected subjects, but the combination therapy has high rate of side effects. This phase Ⅱ randomized controlled study compares efficacy and feasibility of GEM+S-1 with GEM alone in patients with locally advanced and metastatic pancreatic cancer and performance status of 0-2, aiming at patients in rather ordinary clinical settings.

Inclusion Criteria:

1. Histologically or cytologically proven unresectable pancreatic carcinoma
2. There must be measurable lesions with multislice CT
3. ECOG Performance status 0-2
4. No other active cancer
5. No previous therapy such as radiotherapy, chemotherapy and immunotherapy
6. Adequate organ functions are preserved as WBC more than 4000/mm3,Hb more than 8.0g/dl,neutrophil more than 2000/mm3,platlet more than 100,000/mm3, AST less than 2.5 x normal or less than 5.0 x normal if the patient had known liver metastasis, bilirubin less than 2.0mg/dl, Ccr more than 60ml/min
7. No serious complications
8. Be able to eat food
9. Life expectancy of more than 8 weeks duration
10. Informed consent is obtained-

Exclusion Criteria:

1. Interstitial pneumonia
2. Uncontrollable diabetes, liver dysfunction, angina pectoris,or myocardial infarction with its onset within 3 months
3. Serious infection
4. Pregnant or lactating females
5. History of serious drug allergy
6. Serious other complications
7. Uncontrolled mental disorders -