DISEASE CHARACTERISTICS:

• Histologically confirmed medullary thyroid carcinoma meeting the following criteria:

  • Hereditary (multiple endocrine neoplasia [MEN] 2A or 2B)
  • Unresectable, recurrent, or metastatic disease
  • Prior characteristic germline mutation in the RET proto-oncogene documented
• Previously untreated patients are eligible if their tumors are not surgically resectable

• Measurable disease, defined by RECIST as at least one lesion that can be accurately measured in at least one dimension with longest diameter of at least 20 mm by conventional techniques or at least 10 mm by spiral CT scan

  • Superficial (easily palpable) lymph nodes will be considered measurable
• No pheochromocytoma as evidenced by elevated plasma-free metanephrines

PATIENT CHARACTERISTICS:

Inclusion criteria:

• Lansky (≤ 10 years of age) or Karnofsky (> 10 years of age) performance status 60-100%
• Peripheral absolute neutrophil count ≥ 1,500/μL
• Platelet count ≥ 100,000/μL
• PT and PTT ≤ 1.5 times upper limit of normal (ULN)
• Bilirubin ≤ 1.5 times ULN
• AST and ALT ≤ 2.5 times ULN (5 x ULN if hepatic metastases)

• Creatinine clearance ≥ 60 mL/min OR age-adjusted serum creatinine according to the following schedule:

  • 1 mg/dL (male and female 5 to < 10 years of age)
  • 1.2 mg/dL (male and female 10 to < 13 years of age)
  • 1.5 mg/dL (male 13 to < 16 years of age)
  • 1.4 mg/dL (female 13 to < 16 years of age)
  • 1.7 mg/dL (male ≥ 16 years of age)
  • 1.4 mg/dL (female ≥ 16 years of age)
• Negative pregnancy test
• Patients of child-bearing or child-fathering potential must be willing to use a medically effective form of birth control, which includes abstinence, during and for 2 months after completion of study therapy

• Must be able to take one of the oral formulations of vandetanib

  • Administration of the liquid form of vandetanib via a nasogastric tube or gastrostomy is allowed

Exclusion criteria:

• Pregnant or breastfeeding females

• Serum potassium < 3.5 mEq/L OR serum calcium or magnesium below the lower limits of normal

  • Correction of these electrolyte abnormalities with supplements is allowed
• History of arrhythmia (i.e., multifocal premature ventricular contractions, bigeminy, trigeminy, ventricular tachycardia, uncontrolled atrial fibrillation, or left bundle branch block) that is symptomatic or requires treatment (except for controlled atrial fibrillation)
• Patients with a history of congenitally prolonged QTc, a first degree relative with unexplained sudden death under 40 years of age, or a measured QTc (Bazett's correction) longer than 480 msec on ECG
• Patients who have experienced QTc prolongation with other medications requiring discontinuation of that medication
• Diastolic blood pressure above 95% for age on at least 2 of 3 measurements with an appropriate size cuff OR patients who are currently taking antihypertensive therapy
• Other clinically severe or uncontrolled systemic illness that would compromise the participants ability to tolerate vandetanib or compromise study procedures or endpoints

PRIOR CONCURRENT THERAPY:

• Recovered from prior therapy to grade 1 (CTCAE v.3.0)
• At least 4 weeks since prior surgical procedures and surgical incisions must be healed
• At least 4 weeks since prior external beam radiation therapy
• At least 28 days since prior cytotoxic chemotherapy
• At least 7 days since prior anticancer biological therapy (e.g., biological response modifiers [e.g., cytokines], immunomodulatory agents, vaccines, or differentiating agents)
• At least 30 days since prior monoclonal antibody therapy
• At least 30 days since prior investigational agents
• At least 72 hours since prior short-acting colony-stimulating factors (e.g., filgrastim [G-CSF] or sargramostim [GM-CSF])
• At least 7 days since prior long-acting colony-stimulating factors (e.g., pegfilgrastim)
• Patients who have previously undergone a thyroidectomy should be on thyroid hormone replacement therapy
• No other concurrent forms of cancer chemotherapy, radiation therapy, immunotherapy, or investigational agents
• At least 14 days since prior and no concurrent drugs that prolong QTc