Combretastatin A4 Phosphate in Treating Patients With Advanced Anaplastic Thyroid Cancer

DISEASE CHARACTERISTICS: * Histologically confirmed\* anaplastic or poorly differentiated variant thyroid cancer, including 1 of the following: * Recurrent/regionally advanced disease no longer amenable to definitive curative surgery or radiotherapy * Untreated metastatic disease NOTE: \*If original/diagnostic tumor blocks are unavailable, tumor must be accessible for pretreatment core needle biopsy * Must have relapsed or progressed during or after prior combined modality therapy (e.g., systemic chemotherapy and radiotherapy) for regionally advanced (but not metastatic) disease * Measurable or evaluable disease * Patent trachea and airway by screening direct and indirect laryngoscopy\* NOTE: \*For patients with bulky thyroid/neck masses and/or suspected airway obstruction * No active brain metastases, as evidenced by any of the following: * Symptomatic involvement * Cerebral edema by CT scan or MRI * Radiographic evidence of progression since definitive therapy * Continued requirement for corticosteroids PATIENT CHARACTERISTICS: Age * 18 and over Performance status * ECOG 0-2 Life expectancy * At least 12 weeks Hematopoietic * Absolute granulocyte count at least 1,500/mm\^3 * Platelet count at least 75,000/mm\^3 * Hemoglobin at least 8.5 g/dL Hepatic * Bilirubin no greater than 1.5 times upper limit of normal (ULN) * ALT and AST no greater than 3.5 times ULN Renal * Creatinine no greater than 1.5 times ULN Cardiovascular * LVEF at least 50% by MUGA * EKG normal * No evidence of prior myocardial infarction (e.g., significant Q waves), QTc greater than 450 msec, or other clinically significant abnormalities * No history of angina (even if controlled by medication) * No congestive heart failure * No uncontrolled atrial arrhythmias * No clinically significant arrhythmias, including any of the following: * Conduction abnormalities * Nodal junctional arrhythmias and dysrhythmias * Sinus bradycardia or tachycardia * Supraventricular arrhythmias * Atrial fibrillation or flutter * Syncope or vasovagal episodes * No significant heart wall abnormality or heart muscle damage by MUGA * No uncontrolled hypertension (blood pressure consistently greater than 150 mm Hg systolic and 100 mm Hg diastolic regardless of medication) * Patients with previous hypertension are allowed provided there is clinical documentation of controlled blood pressure for 2 months prior to study enrollment * No symptomatic peripheral vascular disease * No symptomatic cerebrovascular disease Other * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective contraception * No grade 2 or greater preexisting motor or sensory peripheral neuropathy * No uncontrolled hypokalemia or hypomagnesemia * No concurrent serious infection * No other nonmalignant medical illness that is uncontrolled or whose control may be jeopardized by study therapy * No psychiatric disorders or other conditions that would preclude study compliance PRIOR CONCURRENT THERAPY: Biologic therapy * No concurrent biologic therapy * No concurrent immunotherapy * No concurrent prophylactic colony-stimulating factors (e.g., filgrastim \[G-CSF\] or sargramostim \[GM-CSF\]) Chemotherapy * See Disease Characteristics * At least 3 weeks since prior chemotherapy (6 weeks for nitrosoureas or mitomycin) * No other concurrent chemotherapy Endocrine therapy * See Disease Characteristics * No concurrent hormonal therapy, except any of the following: * Gonadotropin-releasing hormone agonists for hormone-refractory prostate cancer * Hormone replacement therapy * Oral contraceptives * Megestrol for anorexia/cachexia Radiotherapy * See Disease Characteristics * More than 4 weeks since prior radiotherapy with progressive disease beyond radiation ports * No prior radiotherapy to more than 30% of the bone marrow * No concurrent radiotherapy Surgery * See Disease Characteristics * More than 4 weeks since prior major surgery Other * At least 6 weeks since other prior therapy associated with delayed toxicity * No prior therapy for metastatic disease * No concurrent medication(s) known to prolong the QTc interval, unless medication(s) can be held for at least 72 hours before, during, and for at least 6 hours after study drug administration * No other concurrent investigational therapy * No other concurrent antineoplastic or cytotoxic therapy