What is Imiquimod (Aldara®)?
Imiquimod cream is available both as branded Aldara® or as a generic Imiquimod cream. The cream is used in the treatment of some types of skin cancer & genital warts. The cream works by stimulating the immune system to attack the skin cancer cells. It is commonly used in the skin cancer clinic.
How is Imiquimod cream used?
The cream is applied at night to the affected area that also includes application of the cream to a 1cm margin of healthy looking skin around the lesion. This ensures that any abnormal skin cells outside of the visible edge of the lesion are also treated. The cream is then washed off in the morning.
Wash your hands after applying the cream. You may apply moisturiser around 20-30 minutes after application.
The treatment is not approved in Australia for use immediately next to the eyes, mouth, nose or ears. However, many skin cancer doctors will be comfortable using the treatment in these areas – particularly the nose or ears. Particular care should be taken when used near the eyes.
How often should I used Imiquimod, and for how long?
There are a range of different treatment schedules & it’s important to follow the specific advice given to you. A starting-point is the following:
- For superficial Basal Cell Carcinoma: 5 nights per week (monday to friday) for 6 weeks.
- For Solar Keratosis: 3 nights per week for 4 weeks – this may be repeated after a month’s gap (rest) if required.
- For Intraepithelial Carcinoma: A variety of off-license treatment schedules are used – similar schedule to superficial Basal Cell Carcinoma.
It’s not possible to be prescriptive about duration of treatment because some people get a more severe local reaction whilst others get only minor side effects. For more severe reactions, there may be a treatment gap prescribed so that the same number of days treatment is spread over a longer period.
What are the side effects of Imiquimod cream?
Local Skin Reactions are to be expected and indicate that the cream is working:
- Itching, Burning and/or discomfort are very common.
- Redness – to be expected
- Erosions (common),
- Ulceration, Oozing, Weeping, Scabbing/crusting – these indicate a more severe reaction
There is great variation in how sensitive skin is to these side effects. Severe reactions will mean that the treatment should be reduced in intensity – it may be stopped or may be reduced in frequency. Studies suggest that “breaks” in treatment (provided the number of days application is the same) do not reduce the effectiveness.
There may be reduced Pigmentation (or less commonly increased pigmentation) following treatment (sometimes permanent).
Systemic Flu-like symptoms may also occur:
- Headache, muscle aches, Backache
- Nausea, Diarrhoea
These systemic effects are caused by activation of the immune system which is how the Imiquimod works. There is no need to stop the treatment when the symptoms are mild and can be controlled with paracetamol.
How effective is Imiquimod for Skin Cancer Treatment?
As a rough guide only (studies vary):
- Solar Keratosis: Bear in mind that the treatment is approved in Australia for treating up to 5 cm² at a time & Solar Keratosis often affects a much wider area of skin than this. Treatment may be recommended off-license for a wider area however. Five randomised trials12345 indicate that up to 72% of patients achieve a 75% clearance. Another way of looking at it is that complete clearance is achieved in 45% to 57%.
- Superficial Basal Cell Carcinoma: 82% for superficial BCCs6 though Imiquimod t should only be used for this type of BCC. A biopsy is usually required prior to treatment. Generally not recommended on the head & face (less effective).
- Intraepithelial Carcinoma: Imiquimod is 73% effective.7