Inclusion Criteria

DISEASE CHARACTERISTICS:

- Histologically confirmed adenocarcinoma of the colon

- 15 cm above anal verge

- Stage III disease (any pT, N1-2, M0)

- No rectal cancer

- Must have undergone curative radical resection (R0 resection) within the past 6 weeks

PATIENT CHARACTERISTICS:

Age

- 18 and over

Performance status

- WHO 0-1

Life expectancy

- Not specified

Hematopoietic

- Absolute neutrophil count ≥ 1,500/mm^3

- Platelet count ≥ 100,000/mm^3

Hepatic

- AST ≤ 5 times upper limit of normal (ULN)

- Bilirubin ≤ 1.5 times ULN

Renal

- Creatinine ≤ 1.5 times ULN

Cardiovascular

- None of the following conditions within the past 6 months:

- Myocardial infarction

- Unstable angina

- Symptomatic congestive heart failure

- Serious uncontrolled cardiac arrhythmia

- Cerebrovascular accident or transient ischemic attack

- Deep vein thrombosis

- Other significant thromboembolic event

Pulmonary

- No pulmonary embolism within the past 6 months

Gastrointestinal

- No active gastric or duodenal ulceration within the past year

- No gastrointestinal bleeding within the past year

- No partial or complete bowel obstruction

- No known chronic malabsorption

- No active inflammatory bowel disease or chronic diarrhea (more than 4 stools/day)

Other

- Not pregnant or nursing

- Fertile patients must use effective contraception

- HIV negative

- No AIDS-related illness

- No prior hypersensitivity to fluorouracil, leucovorin calcium, celecoxib, other COX-2
inhibitors, NSAIDs, salicylates, or sulfonamides

- No other severe acute or chronic medical condition or laboratory abnormality that
would preclude study participation, study drug administration, or study results
interpretation

- No psychological, familial, sociological, or geographical condition that would
preclude study compliance

- No concurrent active infection

- No other malignancy within the past 5 years except adequately treated carcinoma in
situ of the cervix or basal cell or squamous cell skin cancer

PRIOR CONCURRENT THERAPY:

Biologic therapy

- No concurrent sargramostim (GM-CSF) or molgramostim

Chemotherapy

- Not specified

Endocrine therapy

- No more than 4 weeks of concurrent orally/nasally inhaled steroids over a 6-month
period

- Concurrent mometasone (or fluticasone) allowed if patients require ≥ 4 weeks of
inhaled steroid therapy

- At least 30 days since other prior steroids

- No concurrent hormonal therapy

Radiotherapy

- No concurrent radiotherapy

Surgery

- See Disease Characteristics

- No prior total colectomy or other major surgery that would result in substantial
alteration in transit to absorption of oral medication

Other

- More than 30 days since prior investigational medication

- No prior systemic anticancer treatment for colon cancer

- No concurrent prophylactic fluconazole

- No concurrent lithium

- No concurrent chronic* use of full dose aspirin, nonsteroidal anti-inflammatory drugs
(NSAIDs), or cyclo-oxygenase-2 (COX-2) inhibitors

- Aspirin at cardioprotective doses (i.e., 80 mg daily or equivalent) allowed

- No concurrent participation in any other clinical study

- No other concurrent experimental agents (e.g., other COX-2 inhibitors, matrix
metalloproteinase inhibitors, inhibitors of the vascular endothelial growth
factor/Flk-1 pathway, or inhibitors of the epidermal growth factor receptor pathway)
NOTE: *Chronic use is defined as a frequency of 7 consecutive days (1 week) for more
than 3 weeks/year or more than 21 days throughout the year