Celecoxib Combined With Fluorouracil and Leucovorin in Treating Patients With Resected Stage III Adenocarcinoma (Cancer) of the Colon

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