Inclusion Criteria

DISEASE CHARACTERISTICS:

- Histologically or cytologically confirmed advanced solid tumor not amenable to
conventional surgery, radiotherapy, or chemotherapy

- No brain metastases or primary brain tumors

PATIENT CHARACTERISTICS:

Age:

- 18 and over

Performance status:

- ECOG 0-1

Life expectancy:

- At least 12 weeks

Hematopoietic:

- WBC at least 3,500/mm^3

- Granulocyte count at least 1,500/mm^3

- Platelet count at least 100,000/mm^3

- Hemoglobin greater than 9.0 g/dL

Hepatic:

- Bilirubin less than 1.6 mg/dL

- AST and ALT less than 2 times upper limit of normal

- PT and PTT normal OR

- INR less than 1.1

Renal:

- Creatinine less than 1.5 mg/dL OR

- Creatinine clearance greater than 60 mL/min

Cardiovascular:

- No New York Heart Association class III or IV heart disease

Other:

- Not pregnant or nursing

- Negative pregnancy test

- Fertile patients must use effective contraception

- No extensive signs of macular degeneration, including exudative or atrophic macular
lesions reducing corrected vision to less than 20/40

PRIOR CONCURRENT THERAPY:

Biologic therapy:

- Not specified

Chemotherapy:

- See Disease Characteristics

- At least 3 weeks since prior chemotherapy (6 weeks for mitomycin or nitrosoureas) and
recovered

- Prior platinum-containing agents and taxane exposure allowed with no evidence of
neurotoxicity

Endocrine therapy:

- Not specified

Radiotherapy:

- See Disease Characteristics

- At least 4 weeks since prior radiotherapy and recovered

Surgery:

- Not specified

Other:

- No concurrent vitamin A supplements

- No concurrent supplemental antioxidants