Patients : total 220 patients
* Extrahepatic bile duct cancer : 55 patients for administration of COX2 55 patients for control group
* Pancreas cancer : 55 patients for administration of COX2 55 patients for control group
Indication
* After operation of extrahepatic bile duct cancer or pancreas cancer
* Age : 19 - 70 years old
* The patients who agree to consent sheet.
Contraindication
* Impossible of administration due to severe postoperative morbidities (bleeding, bowel obstruction, pancreatic fistula, biliary fistula)
* Preexisting heart disease: Ischemic heart disease, Heart failure. Severe uncontrolled hypertension (systolic BP\>160)
* Renal insufficiency: CCR \< 50 or serum creatinin \>3.0
* Hepatic insufficiency: Liver cirrhosis or active hepatitis
* Preexisting allergic reaction history for NSAIDs or Sulfonamide
* Current drug intake: Warfarin. Lithium, Fluconazole, Aspirin, Celecoxib
* Preexisting Asthma. Especially aspirin-sensitive asthma.
* Contraindications to aspirin, clopidogrel or celecoxib
* The patients who refuse trial
* The patients who has Psychogenic problem
Allocation
* We will allocate patients randomly, to administration group or control group
Methods
* From postoperative third day, administration will be started
* celecoxib 200mg bid for 6 months for administration group
* Follow up and assess recurrence rate and survival rate
