Preoperative Sequential Short-course Radiation Therapy and FOLFOX for Locally Advanced Rectal Cancer

Inclusion Criteria:

• Asian

• ECOG (Eastern Cooperative Oncology Group) performance status 0-2

• Pathologically confirmed rectal cancer (rectal cancer located 10 cm or low from theanal verge in pelvis MRI)

• Histologic type: adenocarcinoma, mucinous carcinoma, and signet ring cell carcinoma

• Locally advanced rectal cancer with one or more of the following factors based onpelvis MRI: cTanyN1-2, cT3-4N0, or presence of extramural vascular invasion

• MRI findings such as pelvic lymph node metastasis, anal sphincter invasion, and T4bare not included in the exclusion criteria, which cases will be enrolled by theresearcher's discretion

• Patients with appropriate organ (bone marrow, kidney, liver) function

• A person who understands the study and willing to provide informed consent

Exclusion Criteria: (one of the following criteria)

• Colon cancer or rectal cancer located more than 10 cm from the anal verge

• Stage I rectal cancer (clinical stage cT1-2N0)

• Clinically or pathologically diagnosed distant metastasis (cTanyNanyM1)

• Familial adenomatous polyposis

• Hereditary nonpolyposis colorectal cancer

• History of chemotherapy or radiotherapy within 6 months

• History of colorectal cancer or other type of malignancy within 5 years (except forcured nonmelanoma skin or in situ cervical cancer)

• Comorbidities that make it difficult to undergo chemotherapy or radiotherapy

• Bone marrow suppression with neutrophil count <2 ×109/L or platelet count <100 ×109/L prior to the first chemotherapy

• Peripheral sensory neuropathy with functional impairment (grade 2 or higher)

• Severe renal dysfunction (GFR ≤30ml/min by Wright or Cockroft formula)

• Severe hepatic dysfunction

• Genetic problems such as galactose intolerance, Lapp lactase deficiency orglucose-galactose malabsorption

• Taking tegafur, gimeracil, and oteracil potassium complex and those within 7 days ofdiscontinuation

• Taking sorivudine or brivudine

• Significant heart disease or myocardial infarction within the last 6 months

• Hereditary diseases or history of coagulopathy

• Central nervous system disorders with disability or mental disorders

• Pregnant or lactating women

• Currently participating in other clinical trials or receiving research medication

• Unhealed wounds, fractures, peptic ulcer, abscesses in the abdominal cavity

• Active gastrointestinal bleeding

• Active infections requiring antibiotics for injection

• Emergency Surgery

• History of hypersensitivity to the drugs in study protocol

• Patients with non-malignant tumor diseases

• Dihydropyrimidine dehydrogenase deficiency

• Not willing to participate