DISEASE CHARACTERISTICS:

• Visible sun-induced damage to the skin as assessed by the study dermatologists
• No inflammation of the skin on the lateral forearms
• No more than 10 actinic keratoses on the left forearm, and no actinic keratoses in the treatment area

• Resident of Pima or an adjoining Southern Arizona county

  • Patients outside of Pima County are eligible but the study will be carried out in its entirety at the University of Arizona

PATIENT CHARACTERISTICS:

• History of treated basal cell carcinoma and/or squamous cell carcinoma of the skin at any site other than the left forearm allowed if excision or topical treatment was completed more than 30 days ago (60 days for radiotherapy)

  • History of treated basal cell carcinoma and/or squamous cell carcinoma of the skin on the left forearm allowed 6 months after treatment is completed
• Must agree to avoid sun exposure to the left forearm as much as possible
• Not pregnant or nursing
• Negative pregnancy test
• Fertile patients must use effective contraception
• Not moderately to highly immunosuppressed by virtue of medication or disease, except for mildly suppressive disorders (e.g., diabetes mellitus or on mildly immunosuppressive therapy such as inhaled steroids for asthma)
• No serious concurrent illness that could interfere with study participation
• No active peptic ulcer disease, bleeding disorder, renal failure (creatinine > 2.0 mg/dL), or porphyria
• No known hypersensitivity to diclofenac sodium, eflornithine, acetylsalicylic acid, or NSAIDS
• No evidence of serious underlying medical conditions as demonstrated by abnormal values on baseline laboratory assessment

PRIOR CONCURRENT THERAPY:

• More than 6 months since prior chemotherapy and in complete remission
• More than 60 days since prior and no concurrent oral diclofenac sodium (Cataflam®, Voltaren®, Voltaren-XR®) or combination of diclofenac and misoprostol (Arthrotec®)
• More than 60 days since prior and no concurrent IV eflornithine hydrochloride
• More than 30 days since prior and no concurrent topical retinoids, steroids, imiquimod (Aldara®), aminolevulinic acid HCl (Levulan®), eflornithine (Vaniqa®), diclofenac sodium gel (Solaraze®), or fluorouracil at any site
• More than 30 days since prior and no concurrent topical medication, other than emollients or sunscreens, on the left forearm
• Not undergoing concurrent bone marrow or solid organ transplant
• No other concurrent topical therapy at any site
• No concurrent immunosuppressive therapy (e.g., systemic chemotherapy or rheumatologic agents such as infliximab [Remicade®])
• No concurrent sunscreen use to the left forearm
• No concurrent active therapy for any invasive cancer

• No concurrent non-steroidal anti-inflammatory drugs (NSAIDs) for more than 14 days per month for arthritic and other pain conditions

  • Concurrent daily aspirin (81-325 mg) or acetaminophen allowed
• Concurrent prednisone or other steroids with doses up to 20 mg/day (or the equivalent dose) allowed
• At least 30 days since prior and no concurrent enrollment on other investigational drug or device trial