Published November 2006
Updated: August 20, 2014
Treatment of Actinic Keratoses and Basal Cell Carcinomas with Topical Imiquimod
Topical imiquimod (Aldara®) has been granted approval by Health Canada for treating actinic keratoses and basal cell carcinomas (BCC). Imiquimod is formulated as a cream that is applied topically to skin lesions, and is believed to induce the local production of cytokines in the skin such as interferon, which in turn have an antineoplastic effect on certain tumour cells.
For actinic keratoses, topical imiquimod is used two to three times weekly for 16 weeks. As with all treatments for actinic keratoses, accurate clinical diagnosis is important prior to initiating therapy. Lesions that are atypical or that do not respond adequately to standard therapy should be biopsied to rule out invasive carcinoma.
If topical imiquimod is being considered for BCC, it is critically important to be aware that this treatment is recommended ONLY for low risk, superficial BCCs located on the trunk, neck, or extremities (excluding the hands and feet). It is also important to note that the Health Canada approved labelling for topical imiquimod is restricted to uncomplicated BCCs that would be amenable to simple surgical excision, but where patients have chosen not to have such surgery AND are willing to return for regular follow up. Superficial BCCs occur more commonly on the trunk and extremities and usually appear as well circumscribed, scaly red plaques that are barely elevated. In clinical studies topical imiquimod cleared 82% of treated tumours of BCC.(1) The recommended treatment course for a given tumour is 5 times weekly topical application for a total of six weeks. Prior to treatment, the diagnosis of superficial BCC should be confirmed by biopsy. Following treatment with topical imiquimod, any areas that appear suspicious for residual BCC on clinical examination should undergo repeat biopsy and definitive treatment with an alternative therapy if necessary.
Topical imiquimod is NOT considered appropriate treatment for:
- nodular basal cell carcinoma
- sclerosing or morpheaform basal cell carcinoma
- recurrent basal cell carcinoma
- squamous cell carcinoma
- may be considered for lentigo maligna after consultation with a dermatologist
References
Geisse et.al. Imiquimod 5% cream for the treatment of superficial basal cell carcinoma: Results from two phase III, randomized, vehicle-controlled studies. J. Amer. Acad. Dermatol. May 2004: 722-733
Bath-Hextall, F., et al., Surgical excision versus imiquimod 5% cream for nodular and superficial basal-cell carcinoma (SINS): a multicentre, non-inferiority, randomised controlled trial. Lancet Oncol, 2014. 15(1): p. 96-105.
