Inclusion Criteria

DISEASE CHARACTERISTICS:

- Resident of Pima or adjoining Southern Arizona county

- Patients outside of Pima County are also eligible

- Sun damaged skin as judged by the study physician and quantifiable, clinically
diagnosed, and visible actinic keratoses (AK) on both dorsal forearms, with at least
two AK on each arm

- AK lesions must not be clustered, confluent, or too numerous to count accurately

- Presence of AK on sites other than the test area allowed

- No significant inflammation or irritation of the skin of the upper extremities that
is not clinically diagnosed as sun damage or AK

- Patients must agree to limit sun exposure as much as possible and may continue their
normal pattern of sunscreen use

PATIENT CHARACTERISTICS:

Inclusion criteria:

- Females must not be of childbearing potential, and therefore must be post-menopausal
or surgically sterile by hysterectomy

- Not pregnant or nursing

Exclusion criteria:

- Concurrent skin malignancy or disorder of the upper extremities

- Patients with SCC or BCC in an area other than the test area are eligible upon
excision of the SCC or BCC

- Patients who are immunosuppressed by virtue of medication or disease

- Serious concurrent illness that could interfere with study regimen

- Invasive cancer within the past 5 years

PRIOR CONCURRENT THERAPY:

- At least 30 days since prior topical medications to the skin of the upper extremities
except for emollients or sunscreens

- At least 30 days since prior and no concurrent mega-doses of vitamins, defined as any
of the following:

- More than 5 times the recommended daily allowance

- More than 5 capsules of multivitamins

- 400 IU of vitamin E

- 200 μg of selenium

- 1 gm of vitamin C

- At least 6 months since prior and no concurrent therapy for squamous cell carcinoma
(SCC) or basal cell carcinoma (BCC) anywhere in the test area (i.e., the forearms or
hands)

- Treatment for SCC or BCC on sites other than the test area is allowed

- At least 4 weeks since prior surgical biopsy, surgical excision, or cryotherapy for
AK in the test area and the sites must have healed

- At least 6 months since prior topical treatment (e.g., 5-fluorouracil or imiquimod)
for AK

- No concurrent therapy that may interfere with clinical evaluations

- No concurrent topical drug treatment (e.g., retinoids, aminolevulinic acid,
diclofenac sodium, imiquimod, or fluorouracil) to any area of skin, including test
area

- No concurrent enrollment in another clinical trial

- No concurrent topical citrus peel or consumption of citrus peel

- No chemotherapy for cancer within the past 5 years