One of the frequent questions we get here on SkinCancerConnection is about the use of topical medications used to treat pre-cancerous growths such as actinic keratoses which can be a precursor to developing squamous cell skin cancer. Three of the most commonly used medications to treat such lesions include Efudex, Aldara and Carac.  We have asked Doctor Lawrence Green, a practicing dermatologist and Assistant Clinical Professor of Dermatology at George Washington University School of Medicine in Washington DC to answer some questions about these topical chemo creams and how they work.

Welcome Doctor Green. We are glad you could join us here SkinCancerConnection.

Three of the most commonly asked about topical chemo creams include: Efudex, Carac, and Aldara. Are there any other topical medications commonly prescribed for treating precancerous skin lesions?

Zyclara is a new topical cream that is FDA approved to treat precancerous skin growths. It is a less potent version of Aldara, and is meant to use as "field therapy", meaning all over 1 area (like the face or arms) instead of just spot treating like Aldara is used. What conditions can be treated with such topical creams? Topical creams are FDA approved for treating precancerous skin growths called actinic keratoses. Aldara is also FDA approved for treatment of superficial basal cell carcinomas- a less common form of basal cell carcinoma-on the trunk. Some people feel Efudex can also treat superficial basal cell carcinomas on the trunk and there are some small case studies that show this. In my experience, these medications are best used for treating just precancerous actinic keratoses, and not basal cell carcinomas.


Some members question whether freezing is more effective in treating precancerous lesions such as actinic keratoses. What factors go into choosing one treatment over another?

In my opinion, freezing is preferred if the person has just a few precancerous lesions to treat. If they have many, freezing is too cumbersome and a cream is a better choice. On the other hand, to treat just 1 or 2 spots with a cream daily for a few weeks is a lot of trouble when you can just freeze those few spots in the office quickly. I also think freezing gives better results if you are treating just a few lesions, because the dermatologist can focus on just those and be thorough. If there are many spots to treat, it is more difficult to get them all accurately.

What are the possible dangers or side effects of using such topical medications on the skin? Are there any patients who should not be using these medications?

No real dangers, but skin that is precancerous can become very scabbed, red and irritated. But that is what you want and is a desired result. That said, I would not recommend using Carac or Efudex on children or pregnant/nursing women. For Aldara and Zyclara (which are also used in an off label manner to treat warts in children) there are occasional instances of flu like symptoms following their use, especially if the person doesn't wash the area where they applied the cream on the morning following their bedtime application (approximately 8 hours later).