5-Fluorouracil, Bevacizumab, and Radiation Followed by Modified FOLFOX6 and Bevacizumab in Stage II/III Rectal Cancer

Inclusion Criteria: Histologically confirmed Stage I or II rectal cancer Patients must be candidates for preoperative or adjuvant chemoradiation. Patients enrolling in the adjuvant chemoradiation cohort must have undergone surgical resection of the primary rectal tumor between 28 and 56 days (i.e., 4-8 weeks) prior to study treatment. ECOG performance status 0-1 Adequate bone marrow, liver, and kidney function At least 18 years of age Able to give written informed consent Exclusion Criteria: Treatment with prior chemotherapy or radiation for rectal cancer History of myocardial infarction Uncontrolled hypertension, unstable angina, congestive heart failure, serious cardiac arrhythmia requiring medication or peripheral vascular disease History of stroke within 6 months History of abdominal fistula, gastrointestinal perforation, or intrabdominal abscess within 6 months Symptomatic sensory or peripheral neuropathy Prior treatment with anti-angiogenic agents Prior malignancy in the past 5 years Active infections or serious underlying medical condition Major surgery less than 28 days prior Women who are pregnant or lactating Thrombolytic therapy within 10 days of starting bevacizumab PEG tube, G-tube, or external biliary stents Proteinuria Non healing wound, ulcer or fracture History of bleeding diathesis or coagulopathy Hemoptysis Participation in another experimental trial within 28 days Uncontrolled anticoagulant therapy