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Q In patients with actinic keratoses (AK), is a topically applied imiquimod 5% cream more effective than placebo for clearing lesions?
Clinical impact ratings GP/FP/Primary care ★★★★★★☆ Dermatology ★★★★★★☆
2 concurrent randomised controlled trials subsequently merged into 1 trial for data analysis purposes.
blinded (patients, healthcare providers, data collectors, outcome assessors, data analysts, and the sponsor).*
Follow up period:
16 weeks of treatment followed by an 8 week observational period.
24 centres in the US and Canada.
436 otherwise healthy people >18 years of age (mean age 66 y, 87% men) who had 4–8 clinically diagnosed AK lesions within a contiguous 25 cm2 treatment area on the face or balding scalp but not both. Exclusion criteria included previous treatment with imiquimod 5% cream in the treatment area, and allergies to any excipients in the cream.
topical imiquimod 5% cream (n = 215) or placebo (n = 221) applied once per day, 2 days per week, for 16 weeks. The placebo was similar in appearance, and of identical composition to imiquimod 5% cream with the exception of the active ingredient.
complete clearance of AK lesions in the treatment area and adverse effects assessed at weeks 1, 2, 4, 6, 8, 10, 12, 16 (end of treatment), 20, and 24 (end of post-treatment).
Patient follow up:
95% (analysis was by intention to treat).
At 8 weeks post-treatment, more patients in the imiquimod group than in the placebo group achieved complete clearance of AK lesions (table). More patients in the imiquimod group than in the placebo group had itching, burning, and bleeding at the target site (table).
In patients with actinic keratoses, a topically applied imiquimod 5% cream was more effective than placebo for clearing lesions.
AK are rough scaly, premalignant skin lesions generally<1 cm in diameter. Cryosurgery with liquid nitrogen is the most widely used therapy and is the most appropriate therapy when lesions are few.1
Field therapy is most useful for multiple lesions. Options include topical 5% 5-fluorouracil (5-FU), masoprocol, and photodynamic therapy. A meta-analysis by Pierre et al showed the overall efficacy of 5-FU used for 2–8 weeks to be 80%.2 Efficacy is greatest on the face and scalp and least on the dorsum of the hands. Adverse effects include pain, inflammation, and erosions. Masoprocol use is supported by limited data; however in a head to head study against 5-FU, it caused substantially fewer and less severe side effects but was less efficacious.2
Currently available treatments for AK have limitations, particularly for patients with multiple AK on limbs and trunk. The study by Lebwohl et al examined the use of imiquimod 5% cream for the treatment of multiple AK on the head and scalp and confirmed the earlier findings of Stockfleth et al3 of superior efficacy to placebo. The reported complete clearance rate of 45.1% and partial clearance rate (>75% improvement) of 59.1% suggest that imiquimod is less effective than either cryosurgery or 5-FU; however, a direct comparative trial would be required to assess this observation. Cost, efficacy, ease of use, and morbidity all need to be considered when selecting the most appropriate therapy for AK.
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