Inclusion Criteria:

• Histologically confirmed metastatic adenocarcinoma of the colon or rectum for which no further standard chemotherapy is considered to be effective. Patients must have failed 5-FU, CPT-11 and/or oxaliplatin based chemotherapy.
• SWOG performance status 0-1
• ANC>1000, platelets >100,000.
• Total bilirubin < 2 x upper limit of normal. Transaminase (AST and/or ALT) < 2 x upper limit of normal or < 5 x upper limit of normal in patients with liver metastasis.
• Serum creatinine < 1.25 x institutional upper limit of normal.
• Female patients of child-bearing potential must have negative pregnancy test within 7 days before initiation of study drug dosing.

Exclusion Criteria:

• Patient has received any other investigational agent within 28 days of first day of study drug dosing.
• History of another malignancy within 3 years prior to study entry, except curatively treated non-melanoma skin cancer, prostate cancer, or cervical cancer in situ.
• Patient has another severe and/or life-threatening medical disease.
• Patient has an acute or known chronic liver or kidney disease (e.g., chronic active hepatitis, cirrhosis, chronic renal insufficiency).
• Patient has a known diagnosis of human immunodeficiency virus (HIV) infection.
• Patient has received chemotherapy within 4 weeks (6 weeks for nitrosourea, mitomycin-C or any antibody therapy)
• Patients with symptomatic brain metastasis.
• Patient with Grade III/IV cardiac problems as defined by the New York Heart Association Criteria. (e.g. congestive heart failure, myocardial infarction within 6 months of study)
• Medical, social or psychological factors interfering with compliance.
• Patients who have undergone major surgery for any cause less than 4 weeks prior to study entry.
• Patients taking Coumadin® or other agents containing warfarin, with the exception of low dose Coumadin® (1 mg or less) administered prophylactically for maintenance of in-dwelling lines or ports.
• Any peripheral neuropathy > Grade 1.
• Patients with unresolved diarrhea > Grade 1.
• Patients may not have a history of an allergy to sulfonamide drugs.
• Patients may not have active peptic ulcer disease or other contraindications to chronic NSAID use or aspirin use.
• Patients with lactose intolerance.
• Patients taking full-dose NSAIDs, including aspirin, regularly for any reason (e.g., arthritis,history of TIA or myocardial infarction). Patients taking cardiac preventive dose ASA (<81mg daily) are eligible. Patients should stop taking any other NSAIDs 14 days prior to receiving first dose of Celecoxib.
• Patients with hypersensitivity to COX-2 inhibitors, NSAIDS or salycilate.
• Patients taking fluconazole or lithium.