Topical Diclofenac and Topical DFMO Chemoprevention Trial in Subjects With a History of Skin Cancer

Inclusion Criteria * Previous treatment for basal or squamous cell skin cancer stage 0-2 and current evidence of at least actinic keratosis on the upper extremities (upper arms, forearms and hands), neck, face or scalp. * \>18 years of age * Ability to understand and willingness to sign a written informed consent document * ECOG performance status 0-1 * Willing and able to participate for the full duration of the study * Willing to abstain from: * The application of topical medications including prescription and over the counter preparations (e.g., Topical preparations containing corticosteroids or vitamin A derivatives) to intended treatment areas for the duration of the study. Use of moisturizers/emollients and sunscreens on these areas is allowed. * Chronic (defined as \> 3 times/week for more than 2 consecutive weeks/year) NSAID and COX-2 inhibitor use (other than cardioprotective doses of aspirin \< 100 mg po QD) for the duration of the study * Normal organ and marrow function defined as laboratory values falling within the specified ranges for the following tests (performed within 365 days of registration) Hematologic * WBC \>3,000/ul * Hemoglobin \> lower limit of normal * Platelet count \> 100,000/ul Hepatic * Total bilirubin \< 1.5 X ULN * AST (SGOT) \< 1.5 X ULN * ALT (SPGT) \< 1.5 X ULN Renal * Serum creatinine \< 1.5 X ULN BUN \< 1.5 X ULN • Females of childbearing potential must: * Have been using adequate contraception (abstinence, IUD, birth control pills or spermicidal gel with diaphragm or condom) since their last menses * Have a documented negative urine pregnancy test prior to the first dose of study medication. (Females are not considered to be of childbearing potential if they are at least 1 year post-menopausal or have had a tubal ligation, bilateral oophorectomy or hysterectomy) * The effects of DFMO and diclofenac on the developing fetus are unknown. Therefore, all females of childbearing potential and all men capable of fathering a child must agree to use adequate contraception (abstinence, IUD, birth control pills, or spermicidal gel with diaphragm or condom) for the duration of study participation. Exclusion Criteria Any of the following will render a participant ineligible to participate in this study: * Aspirin \>100 mg/day * Chronic (\> 3 times/week for more than a two week period) use of NSAIDs or COX-2 inhibitors * Current use of topical steroids to intended treatment area (forearms) * Cryotherapy to intended treatment area (forearms) within the preceding 3 months * Use of oral or intravenous corticosteroids for more than 2 consecutive weeks Any of the following in the 4 weeks prior to randomization: * Major surgery for any indication * Cytotoxic chemotherapy for any indication (including methotrexate for arthritis) * Anti-cancer treatment of any type other than for a stage 0-2 non-melanoma skin cancer * Hormonal therapy for cancer prevention ((treatment with finasteride/dutasteride for BPH does not render a participant ineligible.) * Radiation therapy Any of the following in the 6 month prior to randomization to the intended treatment area (forearms): * Topical medications for the treatment of actinic keratosis or skin cancer (etretinate, 5-FU, imiquimod, ingenol) * Laser resurfacing, dermabrasion, chemical peel and/or electrodissection ± curettage * Any family history of Ornithine diaminotransferase deficiency in a first degree relative * Any personal history of: * Invasive cancer diagnosed or treated within the past 5 years. Participants who have been in remission for \>5 years and have not required treatment in the past 5 years may be eligible if a study chair or principal investigator believes there is little to no risk of recurrence. * Solid organ or bone marrow transplant * Biopsy proven hepatic cirrhosis * Keloid formation * Photosensitivity disorder * Hypersensitivity or adverse reactions to nonsteroidal anti-inflammatory agents * Oral DFMO for \> 1 month on a prior study * Any disease that predisposes to NMSC * An immunodeficiency disorder or the use of an immunosuppressive drug • Concurrent use of the following medications or treatments: * Systemic therapy with psoralens, immunotherapy, or retinoids. * Cytotoxic chemotherapy for any reason (including methotrexate for arthritis) * Topical or systemic immunosuppressive therapy * Females who are pregnant or lactating. Should a woman become pregnant or suspect she is pregnant while she is participating in this study, she should notify her study physician immediately. * Uncontrolled concurrent illness including ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, uncontrolled symptomatic cardiac arrhythmia, psychiatric illness/social situations that would limit compliance with study requirements or other underlying serious medical condition which, in the investigator's opinion might preclude study participation.