Inclusion Criteria

DISEASE CHARACTERISTICS: Diagnosis of autosomal recessive disorder xeroderma pigmentosum
Diagnosis must be documented by the clinical signs and symptoms listed in standard text
books, e.g.: Sun sensitivity Increased number of freckles and other pigmentary lesions
Cutaneous atrophy and telangiectasia Actinic keratoses Skin cancers Ocular abnormalities
(e.g., photophobia, conjunctivitis, keratitis, or premalignant or malignant tumors of the
eye or lid) allowed Neurologic abnormalities (e.g., progressive hearing loss, diminished
reflexes, or progressive mental deterioration) allowed OR Diagnosis of autosomal dominant
nevoid basal cell carcinoma syndrome Diagnosis must be documented by the clinical signs
and symptoms listed in standard text books, e.g.: Basal cell carcinomas Palmar pits
Skeletal abnormalities Falx calcification History of at least 2 documented skin cancers a
year during the 2 years before study, but currently clear of all skin cancer Patients not
previously treated with isotretinoin must agree to undergo a 1 year follow-up period
without isotretinoin (to facilitate observation of any chronic toxicity and observe for
new tumors) Must undergo appropriate treatment for any skin cancers that arise during
study No evidence of metastatic cancer

PATIENT CHARACTERISTICS: Age: Over 2 Hematopoietic: Complete blood cell counts normal
Hepatic: SGOT or SGPT less than 3 times upper limit of normal (ULN) Triglycerides less
than 200 mg/dL Renal: Creatinine less than 3 times ULN Cardiovascular: No New York Heart
Association class III or IV heart disease Other: No hypersensitivity to parabens (used in
drug formulation) No proven active malignancy except skin cancer Not pregnant Negative
pregnancy test Fertile patients must use effective contraception during and for 1 month
after study therapy

PRIOR CONCURRENT THERAPY: See Disease Characteristics No recent, chronic, high-dose
vitamin A use (greater than 30,000 IU/day) No concurrent supplemental vitamin A No other
concurrent therapy for the skin (except sunscreens) unless approved by the investigators