Inclusion Criteria

DISEASE CHARACTERISTICS:

- Solid organ recipient (kidney, liver, heart, lung, or pancreas) receiving
immunosuppressive agents (e.g., prednisone, other corticosteroid, azathioprine,
cyclosporine, tacrolimus, mycophenolate mofetil)

- At least 6 months since transplant

- At least 2 prior (same event or separate events) basal cell carcinomas (BCC) or
squamous cell carcinomas (SCC) resected

- All visible BCC and SCC resected

PATIENT CHARACTERISTICS:

Age:

- 18 and over

Performance status:

- Not specified

Life expectancy:

- Greater than 2 years

Hematopoietic:

- WBC at least 3400/mm^3

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

- Hemoglobin at least 10.0 g/dL

Hepatic:

- Bilirubin no greater than 1.5 times upper limit of normal (ULN)

- Alkaline phosphatase no greater than 3 times ULN

- SGOT no greater than 3 times ULN

Renal:

- Creatinine no greater than 1.5 times ULN

Other:

- Not pregnant or nursing

- Fertile patients must use two effective forms of birth control for at least 1 month
before, during, and at least 3 years after study

- No history of oral retinoid intolerance

- No significant, uncontrolled hyperlipidemia

- No other significant medical condition or threatened allograft rejection state where
retinoid use would be contraindicated

PRIOR CONCURRENT THERAPY:

Biologic therapy:

- Not specified

Chemotherapy:

- Not specified

Endocrine therapy:

- See Disease Characteristics

Radiotherapy:

- Not specified

Surgery:

- See Disease Characteristics

Other:

- At least 1 year since prior retinoids

- No concurrent oral vitamin A supplements, topical retinoids, or other potentially
irritating skin preparations

- No alcohol during and for 2 months after study