DISEASE CHARACTERISTICS:

• Histologically confirmed advanced solid tumor for which no standard therapy exists
• At least 1 measurable tumor lesion (at least 2 cm) not previously irradiated

• No history of brain metastases

  • Negative brain CT/MRI required for patients with signs and symptoms suspicious for brain metastases

PATIENT CHARACTERISTICS:

Age:

• 18 and over

Performance status:

• ECOG 0-1

Life expectancy:

• Not specified

Hematopoietic:

• WBC greater than 3,000/mm3
• Absolute neutrophil count greater than 1,500/mm3
• Platelet count greater than 100,000/mm3
• Hemoglobin greater than 10 g/dL
• No history of bleeding diathesis

Hepatic:

• Bilirubin no greater than 1.5 times upper limit of normal (ULN)
• ALT less than 2.5 times ULN

Renal:

• Creatinine less than 1.5 mg/dL OR
• Creatinine clearance greater than 60 mL/min

Other:

• No concurrent uncontrolled medical or psychiatric disorders
• No severe iodine allergy
• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY:

Biologic therapy:

• At least 30 days since prior over-the-counter, anticancer biologic agents (e.g., shark cartilage)
• No concurrent over-the-counter, anticancer biologic agents (e.g., shark cartilage)

Chemotherapy:

• At least 3 weeks since prior cytotoxic or cytostatic agents (6 weeks for nitrosoureas or mitomycin)

• Patients with ECOG performance status 0:

  • Any number of prior chemotherapy regimens allowed

• Patients with ECOG performance status 1:

  • No more than 3 prior chemotherapy regimens for metastatic or recurrent disease
  • The same drug given on a different schedule does not count as a different regimen
  • Prior adjuvant chemotherapy for nonmetastatic disease or as part of a concurrent chemoradiotherapy protocol is allowed but does not count as part of the 3-regimen limit

Endocrine therapy:

• Not specified

Radiotherapy:

• See Disease Characteristics
• See Chemotherapy
• At least 3 weeks since prior radiotherapy to nonindicator lesions
• No concurrent radiotherapy

Surgery:

• At least 24 hours since prior minor surgery (e.g., central venous catheter placement)
• At least 4 weeks since prior major surgery (e.g., laparotomy, thoracotomy, or craniotomy)

Other:

• At least 30 days since prior anticancer herbal remedies
• At least 30 days since prior investigational agents
• No concurrent anticancer herbal remedies
• No other concurrent investigational or anticancer medication