Inclusion Criteria:

- Diagnosis of colorectal cancer (either newly diagnosed or recurrent disease) with
evidence of metastatic disease and present or past histological documentation of
adenocarcinoma of the colon or rectum.

- Tumor must be measureable.

- Resolution of all acute toxic effects of any prior radiotherapy or surgical
procedure.

- ECOG performance status 0 or 1. Age >= 18 years.

- Required baseline laboratory.

- Negative pregnancy test.

- Willingness and ability to comply with the treatment plan.

Exclusion Criteria:

- Current enrollment in another clinical trial.

- Prior adjuvant therapy for colorectal cancer <= 6 months prior to randomization.

- Prior systemic anticancer therapy or intra-arterial cytotoxic chemotherapy given as
treatment for metastatic colorectal cancer.

- Known allergy to CPT-11, 5-FU, LV, celecoxib, other COX-2 inhibitors, non-steroidal
anti-inflammatory drugs (NSAIDS), salicylates, or sulfonamides.

- Chronic concomitant use of full-dose aspirin, other NSAIDs or other COX-2 inhibitors
for a chronic nonmalignant condition.

- A requirement for chronic concomitant use of low-dose (cardioprotective) aspirin.

- Chronic oral steroid use for treatment of a non-malignant condition.

- Known ulceration of the gastric or duodenal mucosa <= 30 days prior to randomization.

- Need for concomitant fluconazole or lithium.

- Any known significant bleeding disorder.

- Active inflammatory bowel disease or chronic diarrhea.