Combination of Oxaliplatin, Capecitabine, and Celecoxib With Concurrent Radiation for Rectal Cancer

Inclusion Criteria: * All patients 18 years of age or older, with biopsy proven T3-4N0-2M0 rectal cancer are eligible. * Life expectancy of at least 2 years. * Zubrod performance status of 0-2. * Patients must be able to sign an informed consent. * Adequate bone marrow function: peripheral granulocyte count of \> 1,500 cells/mm3 and platelet count \>100,000/mm3, hemoglobin \> 10 gm/dl and absence of a regular red blood cell transfusion requirement. * Adequate hepatic function with a total serum bilirubin \< 1.5 x ULN; alkaline phosphatase, alanine aminotransferase (ALAT), and aspartate aminotransferase (ASAT) \< 2.5 x the upper limit of normal (ULN); and adequate renal function as defined by a calculated creatinine clearance \> 50 ml/min \[Cockroft-Gault\]. * Other initial cancer diagnosis more than five years ago without evidence of residual or recurrent disease * Prior diagnosis of squamous or basal cell carcinoma of skin,no active disease at the time of enrollment. Exclusion Criteria: * Known metastases * Pregnant or lactating women. Women/men of childbearing potential not using a reliable and appropriate contraceptive method. * May receive no other concurrent chemotherapy or radiation therapy during this trial. * Severe medical problems such as uncontrolled diabetes mellitus or cardiovascular disease or active infections * Prior pelvic radiation * Known active inflammatory bowel disease, Crohn's disease or ulcerative colitis. * Medical conditions that would preclude the patient from definitive surgery at the end of concurrent chemoradiation * Serious, uncontrolled, concurrent infection(s). * Prior severe reaction to fluoropyrimidine therapy, or known hyper-sensitivity to 5-fluorouracil or known dihydropyrimidine dehydrogenase (DPD) deficiency. * Treatment for other carcinomas within the last five years, except cured non-melanoma skin and treated in-situ cervical cancer. * Participation in any investigational drug study within 4 weeks preceding the start of study treatment. * Clinically significant cardiac disease or myocardial infarction within the last 12 months. * History of uncontrolled seizures, central nervous system disorders or psychiatric disability judged by the investigator to be clinically significant, precluding informed consent, or interfering with compliance of oral drug intake. * Other serious uncontrolled medical conditions that the investigator feels might compromise study participation. * Major surgery \<4 weeks of the start of study treatment, without complete recovery. * Lack of physical integrity of the upper gastrointestinal tract or malabsorption syndrome. * Known, existing uncontrolled coagulopathy * Any of the following laboratory values: * Abnormal hematologic values (neutrophils \< 1.5 x 10\^9/L, platelet count \< 100 x 10\^9/L, hemoglobin \< 10 gm/dl) * Impaired renal function (estimated creatinine clearance \<50 ml/min as calculated with Cockroft-Gault equation. * Serum total bilirubin \> 1.5 x upper normal limit. * ALAT, ASAT \> 2.5 x upper normal limit (or \> 5 x upper normal limit in the case of liver metastases). * Alkaline phosphatase \> 2.5 x upper normal limit (or \> 5 x upper normal limit in the case of liver metastases or \> 10 x upper normal limit in the case of bone disease). * Unwillingness to give written informed consent. * Unwillingness to participate or inability to comply with the protocol for the duration of the study. * History of allergic reactions, hypersensitivity reactions to aspirin, nonsteroidal anti-inflammatory drugs (NSAIDs), or sulfonamides