Inclusion Criteria

DISEASE CHARACTERISTICS:

- Histologically confirmed invasive adenocarcinoma of the rectum

- T2, N0 (stage I) disease by endorectal ultrasound (ERUS) scan

- No T1, T3, or T4 disease

- No tumors fixed to adjacent structures by digital exam

- Greatest tumor diameter ≤ 4 cm

- Distal border of the tumor must be ≤ 8 cm from the anal verge by rigid
proctoscopic exam

- No positive perirectal nodes by ERUS scan

- No histologic evidence of metastatic invasion of inguinal lymph nodes

- No metastatic or other primary disease by chest x-ray/CT scan, abdominal and pelvic
CT scan/MRI with contrast, and colonoscopy

- No documented history of familial adenomatous polyposis

- No documented history of hereditary non-polyposis colorectal cancer diagnosed
clinically or by genetic testing

PATIENT CHARACTERISTICS:

Age

- 18 and over

Performance status

- ECOG 0-2 OR

- Zubrod 0-2

Life expectancy

- Not specified

Hematopoietic

- WBC ≥ 3,000/mm^3

- Absolute neutrophil count > 1,500/mm^3

- Hemoglobin > 9.5 mg/dL

- Platelet count ≥ 100,000/mm^3

Hepatic

- AST and ALT ≤ 2.0 times upper limit of normal (ULN)

- Bilirubin ≤ 3 mg/dL

- Alkaline phosphatase ≤ 2.0 times ULN

Renal

- Creatinine clearance ≥ 50 mL/min

Cardiovascular

- No history of New York Heart Association class III-IV congestive heart failure

- No history of symptomatic coronary artery disease

- No history of uncontrolled arrhythmia

- No myocardial infarction within the past 6 months

- No history of any other clinically significant cardiac disease

Gastrointestinal

- No history of inflammatory bowel disease

- No history of difficulty or inability to take or absorb oral medications

Neurologic

- No clinically significant peripheral sensory or motor neuropathy

- No history of uncontrolled seizures or clinically significant central nervous system
disorder

Other

- Not pregnant or nursing

- Negative pregnancy test

- Fertile patients must use effective contraception

- No history of allergy and/or hypersensitivity to capecitabine or oxaliplatin

- No other malignancy within the past 5 years except curatively treated nonmelanoma
skin carcinoma or in situ carcinoma

- No history of psychiatric conditions or diminished mental capacity that would
preclude study compliance or giving informed consent

PRIOR CONCURRENT THERAPY:

Biologic therapy

- Not specified

Chemotherapy

- Not specified

Endocrine therapy

- Not specified

Radiotherapy

- No prior radiotherapy to the pelvis

- No concurrent intensity modulated radiotherapy

Surgery

- Not specified

Other

- No other concurrent investigational drugs

- No other concurrent anticancer treatment