DISEASE CHARACTERISTICS:

• Histologically confirmed leiomyosarcoma

  • Metastatic, locally advanced, or unresectable
• Ineligible for other high priority national or institutional study

• At least 1 unidimensionally measurable lesion documented on radiologic study

  • At least 2 cm by 2 cm
  • Not previously irradiated unless disease progression at the site is evident
• No brain metastases

PATIENT CHARACTERISTICS:

Age:

• 18 and over

Performance status:

• SWOG 0-2

Life expectancy:

• More than 2 months

Hematopoietic:

• WBC greater than 3,000/mm^3
• Neutrophil count at least 1,500/mm^3
• Platelet count greater than 70,000/mm^3
• Hemoglobin at least 10 g/dL

Hepatic:

• Bilirubin less than upper limit of normal (ULN)
• SGOT or SGPT less than 1.5 times ULN*
• Alkaline phosphatase less than 2 times ULN* NOTE: * Less than 5 times ULN if documented liver disease

Renal:

• Creatinine less than 1.5 times normal OR
• Creatinine clearance greater than 60 mL/min
• BUN less than 1.5 times normal

Other:

• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use 2 forms of effective contraception for 4 weeks before, during, and for 4 weeks after study therapy
• No acute infection requiring systemic antibiotics
• No frequent vomiting or medical condition that would preclude intake of oral medication (e.g., partial bowel obstruction)
• No other serious medical or psychiatric illness that would preclude study participation
• No prior malignancy except curatively treated carcinoma in situ of the cervix or skin cancer

PRIOR CONCURRENT THERAPY:

Biologic therapy:

• Not specified

Chemotherapy:

• At least 4 weeks since prior chemotherapy
• No more than 3 prior systemic chemotherapy regimens for metastatic, locally advanced, or unresectable leiomyosarcoma
• Prior dacarbazine allowed

Endocrine therapy:

• Not specified

Radiotherapy:

• See Disease Characteristics
• At least 4 weeks since prior radiotherapy
• No prior radiotherapy to 50% or more of bone marrow
• Concurrent radiotherapy for local control or palliative therapy for painful bony or soft tissue lesion allowed

Surgery:

• At least 4 weeks since prior surgery and recovered

Other:

• Recovered from all prior therapies
• No other concurrent investigational drugs