Study population, screening, and randomization
colorectal cancer, myocardial infarction, Hereditary diseases, heart disease, hepatic dysfunction14, malignant tumors, infection, nonmelanoma skin, fractures, Colon cancer, male/female, lactase deficiency, hypersensitivity, Unhealed, disability
MUCINOUS CARCINOMA, ABSCESSES, BONE MARROW SUPPRESSION, ONCOLOGY, COLORECTAL CANCER, GASTROINTESTINAL BLEEDING, MALIGNANT TUMORS, EMERGENCY, HEREDITARY DISEASE, CENTRAL NERVOUS SYSTEM DISORDER, RECTAL CANCER, SIGNET RING CELL CARCINOMA, PERIPHERAL SENSORY NEUROPATHY, INFECTION, ADENOCARCINOMA, COLON CANCER, GALACTOSE INTOLERANCE, HYPERSENSITIVITY, FAMILIAL ADENOMATOUS POLYPOSIS, METASTASIS, MYOCARDIAL INFARCTION, HEART DISEASE, LYMPH NODE METASTASIS, HEREDITARY NONPOLYPOSIS COLORECTAL CANCER, PEPTIC ULCERS
Patients with LARC are eligible for enrollment in this trial. They will be identified by the investigators and referred to the institutional multidisciplinary team for eligibility verification. The primary investigator will take charge of the final enrollment based on the inclusion/exclusion criteria (Table 
Inclusion and exclusion criteria1) A male/female adult aged between 20 and 75 years2) Race: Asian3) Eastern Cooperative Oncology Group performance status 0–24) Pathologically confirmed rectal cancer (rectal cancer located 10 cm or low from the anal verge in pelvis MRI)5) Histologic type: adenocarcinoma, mucinous carcinoma, and signet ring cell carcinoma6) Locally advanced rectal cancer with one or more of the following factors based on pelvis MRI: cTanyN1-2, cT3-4N0, or presence of extramural vascular invasion7) MRI findings such as pelvic lymph node metastasis, anal sphincter invasion, and T4b are not included in the exclusion criteria, which cases will be enrolled by the researcher’s discretion8) Patients with appropriate organ (bone marrow, kidney, liver) function9) A person who understands the study and willing to provide informed consent1) Colon cancer or rectal cancer located more than 10 cm from the anal verge2) Stage I rectal cancer (clinical stage cT1-2N0)3) Clinically or pathologically diagnosed distant metastasis (cTanyNanyM1)4) Familial adenomatous polyposis5) Hereditary nonpolyposis colorectal cancer6) History of chemotherapy or radiotherapy within 6 months7) History of colorectal cancer or other malignant tumors within 5 years8) Currently under treatment of malignant tumors (except for cured nonmelanoma skin or in situ cervical cancer)9) Comorbidities that make it difficult to undergo chemotherapy or radiotherapy10) Bone marrow suppression with neutrophil count < 2 × 1011) Peripheral sensory neuropathy with functional impairment (grade 2 or higher)12) Severe renal function impairment (creatinine cleaning rate 30 ml/min or less)13) Severe hepatic dysfunction14) Genetic problems such as galactose intolerance, Lapp lactase deficiency, or glucose-galactose malabsorption15) Taking tegafur, gimeracil, oteracil complex and those within 7 days of discontinuation16) Taking sorivudine, brivudin17) Significant heart disease or myocardial infarction within the last 6 months18) Hereditary diseases or history of coagulopathy19) Central nervous system disorders with disability or mental disorders20) Pregnant or lactating women21) Currently participating in other clinical trials or receiving research medication22) Unhealed wounds, fractures, peptic ulcers, abscesses in the abdominal cavity23) Active gastrointestinal bleeding24) Active infection requiring injection with antibiotics25) Emergency surgery26) History of hypersensitivity to drug in the study protocol27) Dihydropyrimidine dehydrogenase deficiency28) Not willing to participateMRI, magnetic resonance imaging