Neoadjuvant Cetuximab, Fluorouracil, and Pelvic Irradiation in Treating Patients With Locally Advanced or Locally Recurrent Rectal Cancer

DISEASE CHARACTERISTICS: * Histologically confirmed rectal adenocarcinoma meeting 1 of the following staging criteria: * Locally advanced disease * Resectable (uT3) disease * Primary gross transmural tumor that is not adherent to adjacent pelvic structures by endorectal ultrasound * Primary tethered or unresectable (cT4 or uT4) disease * Primary tumor is contiguous with or adherent or fixed to adjacent pelvic structures by clinical exam and CT scan * Primary surgery would likely leave residual tumor * Small volume extrapelvic metastases allowed * Recurrent disease after definitive resection * Disease limited to the pelvis * Requires combined modality treatment * Epidermal growth factor receptor status-positive, -negative, or -unknown * If previously treated with adjuvant fluorouracil-based chemotherapy, no disease recurrence during or within 12 months after completion of adjuvant therapy PATIENT CHARACTERISTICS: Age * 18 and over Performance status * ECOG 0 -1 Life expectancy * Not specified Hematopoietic * Absolute neutrophil count ≥ 1,500/mm\^3 * Hemoglobin \> 8.0 g/dL * Platelet count \> 150,000/mm\^3 Hepatic * Not specified Renal * Creatinine ≤ 1.5 times upper limit of normal Cardiovascular * No myocardial infarction within the past 6 months * No evidence of uncontrolled congestive heart failure requiring therapy Other * No other malignancy within the past 5 years except adequately treated basal cell or squamous cell skin cancer or carcinoma in situ of the cervix * No known severe hypersensitivity to cetuximab or any of its excipients * No uncontrolled infection * No high-grade bowel obstruction (bowel lumen ≤ 1 cm) unless patient has undergone protective surgical diversion or endoscopic stenting procedure * No other concurrent medical or psychiatric condition or disease that would preclude study participation * HIV negative * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective contraception during and for at least 3 months after study treatment PRIOR CONCURRENT THERAPY: Biologic therapy * No prior cetuximab * No prior murine or chimeric monoclonal antibody therapy * No prior biological response modifiers for metastatic colorectal cancer * No concurrent anti-vascular endothelial growth factor/Flk-1 monoclonal antibody therapy * No other concurrent antibody therapy or immunotherapy * No concurrent gene therapy * No concurrent vaccine therapy * No concurrent angiogenesis inhibitors, including thalidomide Chemotherapy * See Disease Characteristics * No prior chemotherapy for metastatic colorectal cancer * No other concurrent chemotherapy Endocrine therapy * No concurrent hormonal therapy Radiotherapy * No prior radiotherapy for metastatic colorectal cancer * No prior pelvic radiotherapy * No other concurrent radiotherapy Surgery * See Disease Characteristics * Fully recovered from prior oncologic or other major surgery Other * No other prior therapy that targets the epidermal growth factor receptor pathway * No other concurrent experimental therapy or drugs * No concurrent matrix metalloprotease inhibitors * No concurrent participation in another clinical study