Oxaliplatin, Leucovorin, and Fluorouracil Before and After Radiation Therapy and Surgery in Treating Patients With Rectal Cancer That Can Be Removed by Surgery

DISEASE CHARACTERISTICS:

* Histopathologically confirmed rectal adenocarcinoma meeting the following criteria:

  * Inferior aspect of tumor is \> 4 cm from anal verge on digital examination and pelvic MRI scan
  * Superior aspect of tumor is not higher than the anterior aspect of the S1/S2 interspace on pelvic MRI scan
  * Mesorectal fascia is not threatened or involved (tumor \> 1 mm from mesorectal fascia)
  * Primary tumor meets 1 of the following criteria:

    * T3a-b (mesorectal primary tumor invasion seen ≤ 5 mm beyond muscularis propria) in the presence of 1 of the following:

      * Extra-mural vascular invasion
      * Mesorectal lymph node(s)/tumor deposit(s) with irregular border and mixed signal intensity
    * Any T3c (primary tumor invasion seen \> 5 mm beyond muscularis propria)-T4a (invasion of visceral peritoneum for tumors with a component above peritoneal reflection)
  * Low tumors should not involve levator ani (\> 1 mm gap between tumor and levator ani) or anal sphincters
* No evidence of distant metastases or stage T4b cancer with invasion into adjacent organs or structures
* Must have measurable disease at the baseline visit
* Impending rectal obstruction is permitted if relieved by a non-functioning ileostomy or colostomy
* No disease threatening mesorectal fascia (disease ≤ 1 mm from mesorectal fascia whether this is primary tumor, extra-mural vascular invasion, or tumor deposit with irregular border and mixed signal intensity)

PATIENT CHARACTERISTICS:

* ECOG performance status 0-1
* Hemoglobin ≥ 9 g/dL
* WBC ≥ 3 x 10\^9/L
* Absolute neutrophil count ≥ 1.5 x10\^9/L
* Platelet count ≥ 100 x10\^9/L
* Total bilirubin ≤ 1.5 times upper limit of normal (ULN)
* Alkaline phosphatase ≤ 5 x ULN
* AST or ALT ≤ 2.5 x ULN
* Creatinine clearance ≥ 50 mL/min
* Magnesium and calcium normal
* Candidate for systemic therapy, in the opinion of the primary oncologist
* No known significant impairment of intestinal absorption (e.g., chronic diarrhea, inflammatory bowel disease)
* No evidence of established or acute ischemic heart disease (e.g., left bundle branch block, pathological q-waves, ST elevation, or ST-segment depression) and normal clinical cardiovascular assessment by ECG
* No enlarged pelvic sidewall lymph nodes
* No severe local bowel symptoms of tenesmus or irregularity or frequency of bowel habit precluding accurate assessment of diarrhea
* No pelvic sepsis
* No uncontrolled infection
* Not pregnant or nursing
* Fertile patients must use effective contraception during treatment and for 6 months after completion of treatment
* No other prior or current malignant disease that, in the judgement of the treating investigator, is likely to interfere with study treatment or assessment of response
* No clinically significant cardiovascular disease, including any of the following within the past year:

  * Myocardial infarction
  * Unstable angina
  * Symptomatic congestive heart failure
  * Serious uncontrolled cardiac arrhythmia
* No history of interstitial lung disease (e.g., pneumonitis or pulmonary fibrosis or evidence of interstitial lung disease)

PRIOR CONCURRENT THERAPY:

* No prior pelvic radiotherapy
* No metallic colon stent or rectal stent in situ
* More than 30 days since prior chemotherapy, radiotherapy, hormonal treatment, antibody therapy, immunotherapy, gene therapy, vaccine therapy, angiogenesis inhibitors, matrix metalloproteinase inhibitors, thalidomide, anti-VEGF/Flk-1 monoclonal antibodies, or other experimental drugs