Docetaxel With or Without Vandetanib in Treating Patients With Metastatic Stomach Cancer or Gastroesophageal Junction Cancer

DISEASE CHARACTERISTICS: * Histologically confirmed gastric adenocarcinoma or gastroesophageal junction cancer * Metastatic disease * Measurable disease * No symptomatic CNS metastases PATIENT CHARACTERISTICS: Inclusion criteria: * ECOG performance status 0-1 * Life expectancy ≥ 3 months * ANC ≥ 1,500/µL * Platelet count ≥ 100,000/µL * Bilirubin ≤ 1.5 times upper limit of normal (ULN) * Creatinine \< 1.5 times ULN OR creatinine clearance ≥ 50 mL/min * Potassium ≥ 4.0 mEq/L (supplementation allowed) and ≤ the CTCAE grade 1 upper limit * Magnesium normal (supplementation allowed) and ≤ the CTCAE grade 1 upper limit * Calcium normal and corrected serum calcium ≤ the CTCAE grade 1 upper limit * In cases where the serum calcium is below the normal range, calcium (adjusted for albumin) normal OR ionized calcium normal * ALT and AST ≤ 2.5 times ULN * Alkaline phosphatase ≤ 2.5 times ULN * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective contraception during and for up to 12 weeks after completion of study therapy * Atrial fibrillation allowed if controlled by medication * LVEF ≥ 45% by MUGA or ECHO Exclusion criteria: * Evidence of severe or uncontrolled systemic disease * Any concurrent condition which makes it undesirable for the patient to participate in the trial or which would jeopardize study compliance, in the Investigator's opinion * Uncontrolled infection * Coagulopathy (including warfarin or anti-coagulant related) or bleeding disorder * Peripheral neuropathy ≥ grade 2 * Clinically significant cardiac event, including myocardial infarction or New York Heart Association class II-IV heart disease within the past 3 months * Presence of cardiac disease that, in the opinion of the Investigator, increases the risk of ventricular arrhythmia * History of arrhythmia (i.e., multifocal premature ventricular contractions, bigeminy, trigeminy, ventricular tachycardia, or uncontrolled atrial fibrillation) which is symptomatic or requires treatment (CTCAE grade 3) OR asymptomatic sustained ventricular tachycardia * History of QTc prolongation as a result of other medication that required discontinuation of that medication * Congenital long QT syndrome or a first degree relative with unexplained sudden death under 40 years of age * Presence of left bundle branch block * QTc with Bazett's correction that is unmeasurable or ≥ 480 msec on screening ECG * If a patient has QTc ≥ 480 msec on screening ECG, the screen ECG may be repeated twice (at least 24 hours apart) * The average OTc from the three screening ECGs must be \< 480 msec in order for the patient to be eligible for the study * Hypertension not controlled by medical therapy (systolic blood pressure \[BP\] \> 160 mm Hg or diastolic BP \> 100 mm Hg) * Currently active diarrhea (≥ grade 2) that may affect the ability of the patient to absorb vandetanib * Previous or current malignancies of other histologies within the past 5 years, with the exception of cervical carcinoma in situ and adequately treated basal cell or squamous cell carcinoma of the skin PRIOR CONCURRENT THERAPY: * Recovered from all prior therapy * At least 4 weeks since prior chemotherapy or radiotherapy * No more than one prior chemotherapy regimen for metastatic disease * Prior adjuvant therapy, including chemoradiotherapy, allowed * At least 2 weeks since prior palliative radiotherapy * Up to 3750 cGy palliative radiotherapy to the stomach allowed * No prior therapy with docetaxel * More than 30 days since prior investigational agents * More than 4 weeks since prior and no concurrent or planned participation in another experimental drug study * More than 4 weeks since prior major surgery and recovered * More than 2 weeks since prior and no concurrent medication that may cause QTc prolongation or induce Torsades de Pointes * No concurrent amiodarone * No concurrent potent inducers of CYP3A4 function (e.g., rifampicin, rifabutin, phenytoin, carbamazepine, barbiturates, or Hypericum perforatum \[St. John wort\]) * No prior enrollment or randomization to treatment in the present study