Combination Chemotherapy and Bevacizumab With or Without Radiation Therapy in Treating Patients With Locally Advanced Rectal Cancer

DISEASE CHARACTERISTICS:

* Histologically or pathologically confirmed adenocarcinoma of the rectum

  * Clinical stage T1, N1; T2, N1; T3, N0; or T3, N1 by endorectal ultrasonography (ERUS)

    * No bulky N2 disease by either ERUS or MRI
    * No primary fixed or unresectable (clinical stage T4) rectal cancer or recurrent colorectal cancer limited to the pelvis

      * Primary unresectable rectal cancer is defined as a primary rectal tumor which on the basis of either physical exam, ERUS or pelvic MRI is deemed to be adherent or fixed to adjacent pelvic structures
* Must be a candidate for all of the following:

  * Neoadjuvant chemoradiotherapy
  * Systemic therapy with fluorouracil, leucovorin calcium, oxaliplatin (FOLFOX), and bevacizumab
  * Complete surgical resection via low anterior resection prior to administration of any therapy
* No low-lying tumors deemed to require an abdominal perineal resection
* No large or bulky tumors that require a diverting colostomy or placement of an endorectal stent prior to treatment initiation
* No clinical evidence of metastatic disease

PATIENT CHARACTERISTICS:

* ECOG performance status 0-2
* Absolute neutrophil count ≥ 1,500/mm\^3
* Platelet count \> 150,000/mm\^3
* Hemoglobin \> 8.0 g/dL
* Creatinine ≤ 1.5 times upper limit of normal
* Not pregnant or nursing
* Negative pregnancy test
* Fertile patients must use effective contraception during and for 4 weeks after completion of study therapy
* 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 arterial thrombotic event within the past 6 months, including stable or unstable angina, myocardial infarction (MI), or cerebral vascular accident (CVA)

  * Deep venous thrombosis, pulmonary embolus, MI, CVA, atrial fibrillation, or any other conditions occurring more than 6 months ago allowed provided patient is on stable doses of anticoagulant therapy
* No other medical or psychiatric condition or disease that would preclude study therapy

PRIOR CONCURRENT THERAPY:

* See Disease Characteristics
* No prior chemotherapy or surgery for rectal cancer
* No prior pelvic radiotherapy
* No other concurrent experimental therapy, including any of the following:

  * Chemotherapy
  * Radiotherapy
  * Hormonal therapy
  * Antibody therapy
  * Immunotherapy
  * Gene therapy
  * Vaccine therapy
  * Angiogenesis inhibitors
  * Matrix metalloprotease inhibitors
  * Thalidomide
  * Anti-vascular endothelial growth factor/Flk-1 monoclonal antibody
  * Any other experimental drugs