Short-course Preoperative Chemoradiotherapy Followed by Delayed Operation for Locally Advanced Rectal Cancer

Inclusion Criteria : * Pathologically proven diagnosis of adenocarcinoma of the rectum (located within 8㎝ above the anal verge) * Locally advanced and curatively resectable tumor(cT3-4 classification) evaluated with magnetic resonance imaging(MRI) with or without transrectal ultrasonography(TRUS) * Age ≥18 * Performance Status(ECOG) 0-2 * CBC/differential obtained within 14 days prior to registration on study, with adequate bone marrow function defined as follows: Hemoglobin ≥ 10 g/dl, Absolute neutrophil count(ANC) ≥ 1,500 cells/㎣, Platelets ≥ 100,000cells/㎣ * Metabolic panel within 14 days prior to registration on study, with adequate liver and renal function defined as follows: AST and ALT ≤ 60 IU/L, bilirubin ≤ 1.5 mg/dl, serum creatinine ≤ 1.5 mg/dl * Patient must provide study-specific informed consent prior to study entry Exclusion Criteria : * Any evidence of distant metastases(M1) * Prior invasive malignancy (except non-melanomatous skin cancer and uterine cervical cancer in situ) unless disease free to a minimum of 3 years * Hereditary rectal cancer; Familial adenomatous polyposis(FAP), Hereditary non-polyposis colorectal cancer(HNPCC), etc. * Impending obstruction (except the case with colostomy) * Severe, active comorbidity inappropriate to CRT as follows; Acute bacterial or fungal infection, transmural myocardial infarction within the last 6 months, unstable arrhythmia, angina and/or congestive heart failure, unstable arrhythmia * Pregnancy or women of childbearing potential who are sexually active and not willing/able to use medically acceptable forms of contraception * Unresected synchronous colon carcinoma * Clinically unresectable rectal cancer