['medullary thyroid carcinoma']
['anlotinib', 'placebo']

        Inclusion Criteria:

          1. Signed and dated informed consent

          2. Histological documentation of medullary thyroid carcinoma(MTC),Unable to surgery(Stage
             IV) or metastasis ,With measurable disease (using RECIST1.1)

          3. ECOG PS:0-1,Life expectancy of more than 6 months

          4. main organs function is normal

        Exclusion Criteria:

          1. Prior treatment with Anlotinib or VEGFR-targeted therapies(such as
             Vandetanib,Cabozantinib,Lenvatinib,Sunitinib,Sorafenib etc.)

          2. Subjects received radiotherapy external exposure within 3 months prior to the first
             dose of study drug or plan to be received any anti-cancer treatment during study

          3. Patients suffering from other malignancies currently or within 5 years, except for
             cured cervical carcinoma in situ, non-melanoma skin cancers and superficial bladder
             cancer [ Ta (non-invasive carcinoma), Tis (carcinoma in situ) and T1 (carcinoma
             invasion into lamina propria) ]

          4. CTCAE(4.0) Grade 1 or higher non-remission toxicity induced by any other previous
             treatments，excluding alopecia and Grade 2 or lower neurotoxicity induced by
             oxaliplatin

          5. Patients with factors that could affect oral medication (such as dysphagia etc.)

          6. Patients with pleural effusion or ascites, causing respiratory syndrome (CTCAE Grade 2
             or higher dyspnea [Grade 2 dyspnea refers to Shortness of breath with a small amount
             of activities, affecting Instrumental activities of daily life])

          7. Patients underwent major surgical treatment，open biopsy or significant traumatic
             injury within 28 days prior to assignment
      