Combination Chemotherapy and Intensity-Modulated Radiation Therapy in Treating Patients Undergoing Surgery for Locally Advanced Rectal Cancer

DISEASE CHARACTERISTICS:

• Pathologically confirmed diagnosis of adenocarcinoma of the rectum by biopsy techniquethat does not completely excise the lesion (e.g., fine needle aspiration, core needlebiopsy)

• Located up to 12 cm from the anal verge with no extension of malignant diseaseinto the anal canal

• Clinically determined to be stage T3 or T4,N0-N2, and M0 tumor as determined bythe following assessments:

• Colonoscopy and biopsy within 56 days prior to registration

• History/physical examination (including medication history screen forcontraindications) within 56 days prior to registration

• Contrast-enhanced imaging of the abdomen and pelvis either by computedtomography(CT), MRI, or Positron-emission tomography(PET)-CT (whole bodypreferred) within 56 days prior to registration

• Chest x-ray (or CT) of the chest within within 56 days prior to registrationto exclude distant metastases (except for patients who have had whole bodyPET-CT)

• Transrectal ultrasound (TRUS) within 56 days prior to registration requiredto establish tumor stage

• TRUS not required if clinical exam, CT of the pelvis, and/or MRIdemonstrates T4 lesion

• No synchronous primary colon carcinoma

• No evidence of distant metastases (M1) PATIENT CHARACTERISTICS: Inclusion criteria:

• Zubrod performance status 0-2

• Absolute neutrophil count (ANC) ≥ 1,800/mm³

• Platelet count ≥ 100,000/mm³

• Hemoglobin ≥ 8.0 g/dL (transfusion or other intervention to achieve hemoglobin ≥ 8.0g/dL allowed)

• Aspartate aminotransferase (AST) < 2.5 times upper limit of normal (ULN)

• Alkaline phosphatase < 2.5 times ULN

• Bilirubin ≤ 1.5 times ULN

• Creatinine clearance > 50 mL/min

• Not pregnant or nursing

• Negative pregnancy test

• Fertile patients must use effective contraception

• No prior invasive malignancy except nonmelanoma skin cancer unless disease free for aminimum of 3 years

Exclusion criteria:

• Severe, active comorbidity, defined as follows:

• Unstable angina and/or congestive heart failure requiring hospitalization withinthe past 12 months

• Transmural myocardial infarction within the past 6 months

• Acute bacterial or fungal infection requiring intravenous antibiotics

• Chronic obstructive pulmonary disease exacerbation or other respiratory illnessrequiring hospitalization or precluding study therapy within the past 30 days

• Hepatic insufficiency resulting in clinical jaundice and/or coagulation defects

• AIDS

• Evidence of uncontrolled seizures, central nervous system disorders, orpsychiatric disability judged by the investigator to be clinically significant,precluding informed consent, or interfering with compliance of oral drug intake

• Known, existing uncontrolled coagulopathy, unless clinically stable onanticoagulation therapy for ≥ 2 weeks

• Evidence of peripheral neuropathy ≥ grade 2

• Prior allergic reaction to oxaliplatin or capecitabine

• Lack of physical integrity of the gastrointestinal tract (i.e., severe Crohn diseasethat results in malabsorption; significant bowel resection that would make oneconcerned about the absorption of capecitabine) or malabsorption syndrome that wouldpreclude feasibility of oral chemotherapy (i.e., capecitabine)

• Prior systemic chemotherapy for colorectal cancer (prior chemotherapy allowed providedit was for a cancer other than colorectal cancer)

• Prior radiotherapy to the region of the study cancer that would result in overlap ofradiotherapy fields

• Major surgery within 28 days of study enrollment(other than diverting colostomywithout tumor resection)

• Participation in any investigational drug study within 28 days of study enrollment.

• Concurrent cimetidine, amifostine, and/or depot Sandostatin