Applied Evidence

Guarding against nonmelanoma skin cancer in solid organ transplant recipients

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References

Topical chemoprophylaxis

Topical medications used for cSCC chemoprophylaxis include 5-fluorouracil (5-FU), photodynamic therapy (PDT), imiquimod, ingenol mebutate, topical retinoids, and diclofenac.27 (See TABLE 2.27-40) Of these, the latter 3 are used less commonly because of the small packaging size of ingenol mebutate and the relative lack of efficacy data for topical retinoids and diclofenac.27 Imiquimod is often avoided when treating large surface areas because of the risk of systemic adverse effects associated with cytokine release.27

Chemoprophylaxis options

5-FU is US Food and Drug Administration (FDA)-approved for the treatment of AKs, and is used off-label for treating cSCC in situ (Bowen disease). It is the most commonly used topical therapy for field disease.27-29 5-FU is typically applied once or twice daily for 3 to 4 weeks. Common adverse effects include transient skin irritation and erythema.27

Chemoprophylaxis options

PDT involves topical application of a photosensitizer, such as 5-aminolevulinic acid or methyl aminolevulinate, followed by exposure to a visible light source, leading to antitumor effects on gene expression and destruction of proliferating cells through production of reactive oxygen species.30,31 Evidence is sufficient to support routine use of PDT for AKs and Bowen disease.30 A mild sunburn-like reaction is common following PDT, with transient erythema and discomfort typically lasting 1 to 2 weeks but not typically necessitating analgesic therapy.27

Imiquimod is a ligand that binds to and activates Toll-like receptor 7, leading to enhancement of the cell-mediated antitumor immune response and resultant tissue-­specific apoptosis coordinated by type 1 T-helper lymphocytes.32 Topical imiquimod cream is FDA approved for field treatment of AKs at 2.5%, 3.75%, and 5% concentrations; efficacy has been demonstrated in the SOTR population.33,41 Multiple studies in immunocompetent patients have suggested that imiquimod might be slightly less efficacious than 5-FU.42-44

The tolerability of field treatment with imiquimod has been called into question.27 However, in a 2019 study comparing adverse reactions among 513 immunocompetent patients with field disease who were treated with either 5-FU 5% cream; imiquimod 5% cream; PDT with methyl aminolevulinate; or ingenol mebutate 0.015% gel, a similar or smaller percentage of patients treated with imiquimod reported moderate-to-severe itching, moderate-to-severe pain, and any adverse events, compared to patients treated with the other options.44

Continue to: Diclofenac

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