Capecitabine, Oxaliplatin, Selenomethionine, and Radiation Therapy in Treating Patients Undergoing Surgery For Newly Diagnosed Stage II or III Rectal Adenocarcinoma

You may be eligible if

• DISEASE CHARACTERISTICS:
• Histologically confirmed rectal adenocarcinoma that is involving the distal 12 cm of the rectum (above the anal verge)
• * Staged within 8 weeks prior to initiation of study by endoscopic ultrasound OR MRI or CT scan if endorectal ultrasound is non-conclusive or non-tolerable
• * T3-T4 tumor or evidence of lymph node involvement defined by the presence of at least 1 enlarged peri-rectal lymph node
• No evidence of distant or known metastases
• PATIENT CHARACTERISTICS:
• ECOG performance status (PS) 0-1 OR Karnofsky PS 70-100%
• Life expectancy \> 1 year
• Leukocytes ≥ 3,000/µL
• Absolute neutrophil count ≥ 1,500/µL
• Platelet count ≥ 100,000/µL
• Total bilirubin ≤ upper limit of normal (ULN)
• AST/ALT ≤ 2.5 times ULN
• Creatinine ≤ ULN OR creatinine clearance ≥ 60 mL/min
• Able to receive oral medication
• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective contraception
• No other concurrent or previous malignancies unless disease free for \> 5 years (excluding nonmelanoma skin cancer)
• No neuropathy ≥ grade 2
• No history of allergic reaction attributed to compounds of similar chemical or biologic composition to oxaliplatin, capecitabine, or selenomethionine
• No uncontrolled intercurrent illness including, but not limited to, any of the following:
• * Ongoing or active infection
• * Symptomatic congestive heart failure
• * Unstable angina pectoris
• * Cardiac arrhythmia
• * Psychiatric illness/social situations that would limit compliance with study requirements
• PRIOR CONCURRENT THERAPY:
• No prior radiotherapy to the pelvis
• No prior chemotherapy
• No other concurrent investigational or anticancer agents or therapies
• No concurrent vitamin B6 supplementation (except as part of a standard, multivitamin supplement)