['rectal cancer']
['dexamethasone', 'regorafenib', 'placebo', 'proton pump inhibitor']

        Inclusion Criteria:

          -  Capable of granting informed consent in writing for receiving treatment outlined in
             this protocol

          -  The investigators determines that the patient can receive the treatment outlined in
             this protocol

          -  Histological diagnosis of adenocarcinoma of either the colon or the rectum, regardless
             of RAS mutation

          -  Metastatic colorectal cancer scheduled for treatment with regorafenib

          -  Lesions are either measurable or non-measurable according to RECIST ver. 1.1

          -  Contrasted torso CT within 28 days before enrollment

          -  At least 20 years of age

          -  PS 0-1

          -  Bone marrow, hepatic, and renal functions have all been confirmed as normal within 14
             days prior to initiation of regorafenib treatment

          -  Life expectancy of at least 3 months

        Exclusion Criteria:

          -  Used regorafenib previously

          -  Blood transfusion or granulocyte-colony stimulating factor (G-CSF) administration
             within 14 days

          -  Grade 2 or higher fatigue or malaise or asthenia according to NCI-CTCAE ver. 4.0

          -  History of a different type of cancer according to histological findings or cancer of
             a different primary focus within the past 5 years. The following are excluded:
             carcinoma in situ of the cervix, non-melanoma skin cancer, superficial bladder cancer
             (Ta, Tis, and T1), gastric cancer,non-invasive breast cancer, etc

          -  Highly invasive surgery, an open biopsy, or who have received significant trauma
             within 28 days of initiating regorafenib treatment

          -  Congestive cardiac failure of New York Heart Association (NYHA) >=Class 2

          -  Unstable angina (symptoms at rest),new-onset angina (onset within past 3 months), or a
             history of myocardial infarction within 6 months of initiating treatment

          -  Arrhythmia requiring treatment with anti-arrhythmia drugs

          -  Uncontrollable hypertension

          -  Pleural effusion or ascites causing dyspnea (NCI-CTCAE >=Grade 2)

          -  History of venous or arterial thrombosis or embolism within 6 months prior to
             initiation of treatment, including cerebrovascular accidents, deep vein thrombosis, or
             pulmonary embolism

          -  Patients with active infections of NCI-CTCAE >=Grade 3

          -  Positive for either hepatitis B (HB)s antigen or hepatitis C virus (HCV) antibody

          -  Seizure disorders requiring drug treatment

          -  Cerebral metastases or history of such

          -  History of organ transplant

          -  Symptoms or history of hemorrhagic tendency, regardless of severity

          -  Some form of hemorrhaging (NCI-CTCAE >=Grade 2) within 4 weeks prior to initiating
             treatment

          -  Incurable wound, fracture or ulcer

          -  Renal failure requiring either hemodialysis or peritoneal dialysis

          -  Dehydration symptoms of NCI-CTCAE >=Grade 1

          -  Abusing drugs or who are in a physical, psychological, or social state which might
             impair study participation or evaluation of results

          -  Interstitial lung disease with active signs or symptoms

          -  Have difficulty taking oral drugs

          -  Digestion absorption disorders

          -  Adverse events resulting from previous treatments or procedures which have not yet
             resolved (NCI-CTCAE >=Grade 2)

          -  Received systemic anti-cancer treatments within 2 weeks prior to initiation of
             regorafenib treatment, including chemotherapy, molecular target drugs, immunotherapy,
             or hormone therapy

          -  Poorly controlled glucose tolerance abnormalities due to diabetes mellitus (patients
             using insulin)

          -  Active GI ulcers or a history of such

          -  Glaucoma

          -  Oral steroids are otherwise contraindicated

          -  Either pregnant or nursing. Women who may become pregnant must have a negative
             pregnancy test within 7 days prior to initiating treatment

          -  Women who may become pregnant, or men whose partners may become pregnant, must agree
             to use appropriate contraceptives from granting of consent to 3 months after
             conclusion of regorafenib therapy

          -  Other illnesses or conditions which, according to the judgment of the investigator,
             may result in physical harm caused by the study, or which may impair study compliance
      