Imiquimod (Aldara, Zyclara) is an immune response modifier. It was originally designed to treat genital warts. Currently it is indicated for warts, actinic keratoses (AKs) and superficial basal cell skin cancers. It causes the production of anti-cancer cytokines in your body, including interferon alpha, Interleukin 6 and tumor necrosis factor alpha. These in turn activate Langerhans cells in the skin, which then migrate to the lymph nodes and produce a more intense activation of the immune system, including natural killer cells, other macrophages, and even B cell lymphocytes. This all sounds very technical, but what it essentially means is that it is teaching your immune system to recognize cancerous and precancerous cells. This is the only medication of it’s kind to treat precancers.
One of the benefits of this medication other than that its effects are supposed to be longer lasting since your body should be more likely to recognize new precancerous areas. Another is that when using this treatment as opposed to freezing it is able to treat even lesions that cannot yet be seen. The bad part about this is that you may be more red and inflamed from the treatment than you would expect because of this.
Treatments & Side Effects
The imiquimod 5% treatment for precancers is every day for 2 weeks, then a 2 week break and another two weeks of treatment. If it is for a superficial basal cell skin cancer it is once daily for 5 days per week for 6 weeks. The stronger the reaction to the medication, usually the worse the side effects are. Some people react very mildly and have no problems whatsoever. Others, particularly with basal cell skin cancer or with really extensive sun damage can feel systemically ill and develop flu-like symptoms. This is fortunately relatively rare. The nice thing about the treatment is that there are rarely any long term effects from the treatment. Most superficial basal cells clear without scarring and actinic keratoses typically clear without discoloration as may be left after freezing (cryotherapy). Superficial basal cell treatment does sometimes leave behind long lasting residual hypopigmentation (lightening) or mild redness of the skin, but compared to a surgical scar most people are pleased with the results.