Radiation Therapy, Chemotherapy, and Cetuximab Followed by Surgery, Chemotherapy, and Cetuximab in Treating Patients With Locally Advanced or Metastatic Rectal Cancer That Can Be Removed by Surgery

DISEASE CHARACTERISTICS: * Histologically confirmed adenocarcinoma of the rectum * Locally advanced (T3-4 Nx) or metastatic (T2 N+ M1) synchronous disease * Metastases must be resectable * Primary tumor examined by endorectal echography and MRI * Measurable disease by thoraco-abdomino-pelvic scanner * Disease considered susceptible to treatment with radiotherapy and chemotherapy * No diffuse metastases considered nonresectable * No acute occlusion not caused by colostomy PATIENT CHARACTERISTICS: Inclusion criteria: * ECOG performance status 0-2 * WBC ≥ 4,000/mm\^3 * Absolute neutrophil count ≥ 1,500/mm\^3 * Platelet count ≥ 100,000/mm\^3 * Hemoglobin ≥ 10 g/dL * Creatinine ≤ 130 µmol/L * Transaminases ≤ 5 times upper limit of normal (ULN) * Total bilirubin ≤ 1.5 times ULN * Alkaline phosphatase ≤ 2.5 times ULN * Not pregnant or nursing * Negative pregnancy test * Fertile patients of must use effective contraception Exclusion criteria: * Contraindication to therapy with capecitabine, oxaliplatin, cetuximab, and/or radiotherapy * Impossible to perform translational analyses * Uncontrolled severe illness * Severe renal or hepatic insufficiency * Cardiac insufficiency or symptomatic coronary disease * Sensitive peripheral neuropathy * Uncontrolled diabetes * Other malignancy within the past 10 years except previously treated basal cell skin cancer or carcinoma in situ of the cervix * Impossible to participate in study due to geographic, social, or psychiatric reas…