Bevacizumab, Fluorouracil, Leucovorin Calcium, and Oxaliplatin Before Surgery in Treating Patients With Stage II-III Rectal Cancer

Inclusion Criteria: * Histologically confirmed adenocarcinoma of the rectum in patients with no prior therapy who are candidate for surgical resection * Tumor lesion is 5-15 cm from anal verge * cT2 N+ or cT3-T4 N0 or N+ as assessed by endorectal ultrasound scan (US) * No evidence of distant metastatic disease * Signed informed consent prior to initiation of any study-specific procedure or treatment * Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1 * Able to comply with the protocol, including tissue sampling, imaging studies and surgical intervention * Life expectancy more than 12 weeks * Absolute neutrophil count \>= 1500 per mm\^3 * Platelet count \>= 100,000 per mm\^3 * Hemoglobin \>= 9 g/dL (may be transfused to maintain or exceed this level) * Total bilirubin \< 1.5 x upper limit of normal (ULN) * Aspartate aminotransferase and alanine aminotransferase \< 2.5 x ULN * Calculated creatinine clearance according to Cockroft and Gault formula \>= 50 mL/min * Urine for proteinuria should be \< 2 +; patients discovered to have \>= 2 + proteinuria on dipstick urinalysis at baseline should undergo a 24-hour urine collection and must demonstrate \< 1 g of protein in 24 hours * International normalized ratio =\< 1.5 and activated prothrombin time =\< 1.5 x ULN within 7 days prior to enrollment; the use of full-dose oral or parenteral anticoagulants is permitted as long as the international normalized ratio (INR) or activated partial thromboplastin time (aPT…