Cryo + imiquimod to Right for Actinic Keratosis

Actinic keratoses (AK) are common cutaneous lesions associate with chronic ultraviolet radiation exposure. While most authorities consider AK as a pre-malignant lesion, some consider it as an incipient squamous cell carcinoma (SCC). In addition, the skin around clinically obvious AK lesions has been subject to the same chronic ultraviolet exposure, resulting in genetic damage and mutations, resulting in "field cancerization." Subclinical AKs may progress to clinical AKs, or even de novo invasive SCCs. Among the current therapies for the treatment of AK are excisional surgery, cryosurgery, electrodessication and curettage, topical chemotherapy and light therapies. With cryotherapy, treated lesion clearance rates at 3 months post-treatment after double-freeze thaw cryotherapy has been reported to be around 76-88%; Overall lesion clearance rate at approximately 5 months post-cryosurgery has been reported to be 35-51%. Imiquimod is a topical immune response modifier and a 5% formulation has been approved for the treatment of AKs in the US as a 2x/week for 16 week regimen and in Europe as a 3x/week for 4 week regimen for 1 or 2 courses of therapy. Topical imiquimod treatment may also reduce subclinical lesions in the treatment area, resulting in fewer "new" AK lesions developing over the same period of time when compared to focal treatment. In a comparison of cryosurgery versus imiquimod for the treatment of AKs, Krawtchenko et al reported initial complete clearance rates of 68 and 85% by clinical assessment, respectively. However, the treatment field sustained clearance rate was 4% versus 73%, respectively. Tan et al reported that while application of imiquimod or vehicle following cryosurgery resulted in comparable target AK clearance rates at 12 weeks of 79% versus 76%, respectively, the imiquimod group had fewer total AKs and fewer subclinical AKs. Imiquimod cream at a concentration of 3.75% has been found in Phase 3 studies to be superior to placebo cream with respect to clearance of AKs using a regimen of up to 2 packets (250 mg of cream per packet, 500 mg total) applied daily to the entire face (approximately 200 cm2) for two 2-week treatment cycles separated by a 2-week no-treatment period. This study aims to examine the benefit of cryotherapy in combination with imiquimod 3.75% compared to cryotherapy alone.