Inclusion Criteria

DISEASE CHARACTERISTICS:

- Histologically confirmed advanced adenocarcinoma of the rectum with or without nodal
involvement

- Stage mrT3-4 and/or mrN1-2, M0

- Tumors must express wild type K-ras gene

- No distant metastasis

PATIENT CHARACTERISTICS:

- WHO performance status 0-1

- Able to undergo surgery

- ANC ≥ 1,500/mm^3

- Platelet count ≥ 100,000/mm^3

- Hemoglobin ≥ 100 g/L

- Creatinine clearance ≥ 50 mL/min

- AST ≤ 2.5 times upper limit normal (ULN)

- Total bilirubin ≤ 1.5 times ULN

- Not pregnant or nursing

- Negative pregnancy test

- Fertile patients must agree to use effective contraception during and for 12 months
after completion of study

- No malignancy within the past 5 years with the exception of adequately treated
cervical carcinoma in situ or localized nonmelanoma skin cancer

- No psychiatric disorder that would preclude understanding study-related information,
giving informed consent, or complying with oral drug intake

- No prior existing conditions that would preclude radiotherapy

- No clinically significant (i.e., active) cardiac disease (e.g., congestive heart
failure, symptomatic coronary artery disease, and cardiac arrhythmia even if
controlled with medication) or myocardial infarction within the past 12 months

- No lack of physical integrity of the upper gastrointestinal tract or malabsorption
syndrome

- No serious underlying medical condition that, in the judgement of the investigator,
could impair the ability of the patient to participate in the trial (e.g., active
autoimmune disease or uncontrolled diabetes)

- No known dihydropyrimidine dehydrogenase deficiency

- No known hypersensitivity to trial drugs or hypersensitivity to any other component
of the trial drugs

PRIOR CONCURRENT THERAPY:

- More than 30 days since prior treatment in a clinical trial

- No other concurrent experimental drugs, anticancer therapy, or investigational
treatments

- No prior treatment for rectal cancer

- No prior anti-EGFR antibody therapy (e.g., cetuximab) or small-molecule EGFR
inhibitors (e.g., erlotinib hydrochloride)

- No concurrent treatment with brivudine, lamivudine, ribavirin, or any other
nucleoside analogues

- No organ allografts

- No concurrent drugs contraindicated for use with the trial drugs

- No other concurrent anti-EGFR-targeting agents

- No other concurrent radiotherapy