DISEASE CHARACTERISTICS:

• Histologically confirmed anaplastic* thyroid cancer

  • Not amenable to definitive curative surgery or radiotherapy NOTE: *Papillary, follicular, or other histologies that are mixed or identified in a diagnostic tissue sample are allowed provided a high-grade undifferentiated anaplastic component is present
• Progressive disease after prior cytotoxic chemotherapy (i.e., chemotherapy alone or combined with radiotherapy)

• Measurable or evaluable disease

  • Measurable disease, defined as ≥ 1 unidimensionally measurable lesion ≥ 20 mm by conventional techniques OR ≥ 10 mm by spiral CT scan
  • Measurable disease not in a previously irradiated field
• No symptomatic bulky disease that would impair the airway or impede swallowing (for patients with ECOG performance status 2)
• No known brain metastases

PATIENT CHARACTERISTICS:

Age

• 18 and over

Performance status

• ECOG 0-2 OR
• Karnofsky 50-100%

Life expectancy

• More than 8 weeks

Hematopoietic

• Absolute neutrophil count ≥ 1,250/mm^3
• Platelet count ≥ 100,000/mm^3
• No evidence of bleeding diathesis

Hepatic

• Bilirubin ≤ 1.5 times upper limit of normal (ULN)
• AST and ALT ≤ 3.5 times ULN
• PTT ≤ 1.5 times ULN
• INR < 2.0

Renal

• Creatinine ≤ 1.5 times ULN

Cardiovascular

• No myocardial infarction within the past 6 months
• Patients with evidence of abnormal cardiac conduction (e.g., bundle branch block or heart block) are eligible provided disease has been stable for the past 6 months
• No New York Heart Association class III or IV cardiac disease
• No symptomatic congestive heart failure
• No unstable angina pectoris
• No cardiac arrhythmia
• No uncontrolled hypertension (i.e., systolic blood pressure (BP) > 150 mm Hg OR diastolic BP > 100 mm Hg)

Other

• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective contraception
• Able to swallow oral medication
• No history of allergic reactions attributed to compounds of similar chemical or biological composition to sorafenib
• No ongoing or active infection
• No psychiatric illness or social situation that would preclude study compliance
• No other invasive malignancy within the past 5 years except nonmelanoma skin cancer
• No other uncontrolled illness

PRIOR CONCURRENT THERAPY:

Biologic therapy

• Not specified

Chemotherapy

• See Disease Characteristics

• No more than 2 prior systemic cytotoxic chemotherapy regimens

  • Combined modality systemic cytoxic chemotherapy is considered 1 prior cytotoxic regimen
• At least 7 days since prior chemotherapy and recovered

Endocrine therapy

• Not specified

Radiotherapy

• See Disease Characteristics
• At least 7 days since prior radiotherapy and recovered

Surgery

• Recovered from prior surgery

Other

• No prior sorafenib or other inhibitors of MAP kinase signaling intermediates
• No prior cancer treatment that would preclude study participation
• No concurrent combination antiretroviral therapy for HIV-positive patients
• No other concurrent investigational agents
• No concurrent cytochrome P450 enzyme-inducing antiepileptic drugs (e.g., phenytoin, carbamazepine, or phenobarbital)
• No concurrent Hypericum perforatum (St. John's wort) or rifampin

• No concurrent therapeutic anticoagulation

  • Concurrent prophylactic anticoagulation (i.e., low-dose warfarin) for venous or arterial access devices allowed provided requirements for INR and PTT are met
• No other concurrent anticancer therapy