Today I want to talk about some topical medications that can be used at home to treat actinic keratoses, which are precancerous growths that appear usually in sun exposed areas. Actinic keratoses are precursors of squamous cell carcinoma, with approximately 5% of these lesions developing into squamous cell carcinoma. They appear usually as rough, dry, slightly reddened patches of skin that seem to not go away or heal completely. In the office, the most common method of treatment is cryotherapy with liquid nitrogen which “freezes” the lesions off. However, a person may have many of these lesions and it is not practical to freeze all of them. Typically, no more than about 20 lesions are frozen at any office visit. In most cases, the arms and the face are the areas with the majority of the sun damage. So what can be used to treat these precancers by patients at home and what should you expect?
There are three main creams used to treat actinic keratoses. While they each have different mechanisms of action, they are all designed to help clear up these precancerous lesions of the course of several weeks to months. All are effective and have been tested extensively. The first product used for topical treatment of actinic keratoses was 5-fluorouracil, which is a chemotherapeutic agent that inhibits cells’ ability to reproduce. The most commonly prescribed brands are known by the trademarked names Efudex and Carac. These creams are usually used one to two times daily for up to one month but check with your dermatologist for your specific dose. 5-fluorouracil causes a lot of redness and inflammation of the skin so the area treated will get extremely red and I tell patients that their skin will look as if it were dragged across concrete. It really can make the treated areas look really bad although all the inflammation will clear up and after discontinuation of the cream, the skin will return to normal. A disadvantage of the cream is that often the face is an area we want to treat but not many patients want their faces to look so red and irritated for up to a month! Also, sun avoidance is recommended when using this medicine so summertime is not a good time for treatment. Although the skin can get extremely irritated, the treatment time is only several weeks and it does work well.
Because 5-fluorouracil is so irritating to the skin and can be very patient unfriendly due to the appearance of the skin, there are other creams used that are not as irritating but the treatment time is longer. One cream is imiquimod, and goes by the trade name Aldara. It was originally approved to treat external genital warts but its mechanism of stimulating the immune system has been shown to be effective in treating precancerous lesions. A typical treatment plan with this cream is to use it 2 times each week for up to 4 months, although many dermatologists will alter this plan to use more frequently for a shorter duration. This cream is also irritating to the skin and will cause redness and inflammation. However, because it is only used 2 times/week, the level of irritation is greatly reduced. The main disadvantage to Aldara is that is packaged in small packets and one prescription is for 12 packets. Each packet is about the size of a salt packet you would see at a restaurant. As a result, it is difficult to treat large surface areas, such as an entire arm although it is reasonable to treat the hands or the forehead.