Inclusion Criteria

Inclusion Criteria

- Patients must have histologically proven adenocarcinoma of the rectum with no
evidence of distant metastases.

- The tumor must be clinically Stage II (T3-4 N0 with N0 being defined as all imaged
lymph nodes are < 1.0cm) or III (T1-4 N1-2 with the definition of a clinically
positive node being any node > 1.0cm). Stage of the tumor may be determined by CT
scan, endorectal ultrasound or MRI.

- Patients must have no evidence of distant metastases including liver metastases,
peritoneal seeding, or inguinal lymphadenopathy.

- Patients must not have received prior chemotherapy or pelvic radiation for rectal
cancer, or prior pelvic radiation for any other malignancy that would prevent the
patient from receiving the required radiation treatments for this study.

- Patients must have a life expectancy of 5 years, excluding their diagnosis of cancer
(as determined by the investigator).

- Patients must not have an active concurrent invasive malignancy. Patients with prior
malignancies, including invasive colon cancer, are eligible if they are deemed by
their physician to be at low risk for recurrence. Patients with squamous or basal
cell carcinoma of the skin, melanoma in situ, carcinoma of the cervix, or carcinoma
in situ of the colon or rectum that have been effectively treated are eligible, even
if these conditions were diagnosed within 5 years prior to randomization.

- Patients must be > 18 years of age, ECOG performance status 0-1.

- ANC > 1,500/µl, platelets > 100,000/µl, total bilirubin < 2.0 mg/dl or direct
bilirubin < 1.0 mg/dl, alkaline phosphatase < 3xULN, ALT < 3xULN, creatinine <
1.5xULN.

- The patient must have been evaluated by a surgeon, radiation oncologist and medical
oncologist and all must concur that the patient is appropriate for this study.

- Signed informed consent; able to comply with study and/or follow- up procedures

- Peripheral neuropathy < grade 1

Exclusion Criteria:

- Evidence of metastatic disease.

- Rectal cancers other than adenocarcinoma, i.e., sarcoma, lymphoma, carcinoid,
squamous cell carcinoma, cloacogenic carcinoma, etc.

- Pregnancy or lactation at the time of proposed randomization. Eligible patients of
reproductive potential (both sexes) must agree to use adequate contraception.

- Any therapy for this cancer prior to randomization.

- Synchronous invasive colon cancer.

- Nonmalignant systemic disease (cardiovascular, renal, hepatic, etc.) that would
preclude the patient from receiving any chemotherapy treatment option or would
prevent required follow-up.

- Patients with active inflammatory bowel disease, abdominal fistula, gastrointestinal
perforation, or intraabdominal abscess within 6 months prior to Day 0 or other
serious medical illness which might limit the ability of the patient to receive
protocol therapy.

- Prior pelvic irradiation for any indication.

- Known hypersensitivity to 5-fluorouracil or oxaliplatin

- Psychiatric or addictive disorders or other conditions that, in the opinion of the
investigator, would preclude the patient from meeting the study requirements.