Study to Determine if Contacting Patients With MTC More Frequently Results in Earlier Detection and Treatment of Signs and Symptoms of AEs and Thus a Decrease in the Percentage of Time Patients Experience AEs During First 12 Months on Vandetanib Treatment

Inclusion Criteria:

* Provision of informed consent prior to any study specific procedures
* Female or male aged 18 years and over
* Previously confirmed histological diagnosis of unresectable, locally advanced or metastatic hereditary or sporadic MTC. Documentation must be provided in patient's medical chart
* WHO or ECOG Performance status 0-2
* Negative pregnancy test (urine or serum) for female patients of childbearing potential

Exclusion Criteria:

* Unstable brain metastases or spinal cord compression that require treatment, unless treated at least 4 weeks before first dose and stable without steroid treatment for 10 days
* Major surgery within 4 weeks before randomization
* The last dose of prior chemotherapy received less than 3 weeks prior to randomization
* Radiation therapy not completed prior to the first dose of vandetanib
* Significant cardiac event, superior vena cava syndrome, NYHA classification of heart disease ≥2, within 12 weeks before randomization, or presence of cardiac disease that in the opinion of the Investigator increases risk of ventricular arrhythmia
* Creatinine clearance \<30 ml/min (calculated by Cockcroft-Gault formula),Patients with moderate renal impairment, defined as creatinine clearance ≥30 to \<50 ml/min, must start vandetanib at a reduced dose of 200 mg