Skin Conditions, General | June 21, 2016 | Author: The Super Pharmacist
Topical 5-fluorouracil (5-FU) (Efudix) is a cream that is applied to the skin to treat various skin diseases. It is usually used to treat actinic keratosis, squamous cell carcinoma in situ, and basal cell carcinoma that does not extend deeply into the skin.1 Dermatologists may use topical 5-FU for other skin conditions including warts, psoriasis, vitiligo, and even sunspots. Topical 5-FU destroys sun-damaged and pre-cancerous/cancerous cells by inducing inflammation in the skin. During treating with topical 5-FU, the expected inflammation means patients must endure red, painful, weeping, oozing sores that form crusts and scabs for the duration of treatment and perhaps one to two weeks afterwards. Not surprisingly, patients and doctors are interested in shortening the time required for 5-FU treatment without making the treatment less effective. Recently physicians have began prescribing another topical cream, tretinoin (vitamin A), for two weeks prior to topical 5-FU treatment. While pretreatment with tretinoin is commonly prescribed, does it actually reduce 5-FU treatment times?
Actinic keratosis is the most common, indicated use for topical 5-FU.2 In people with multiple actinic keratosis lesions, 5% 5-FU cream removes 100% of lesions in half of the patients treated, and the cream is more than 90% effective in people with simple actinic keratosis.3,4 Topical 5-FU also appears to provide long-term control of actinic keratosis.5 Treatment usually takes four to six weeks; two to four weeks of active drug treatment with an additional two weeks of redness, blistering, and peeling of the skin.
In the 1960s and 1970s, topical tretinoin was the standard treatment for actinic keratosis and basal cell carcinoma; however, modern studies have shown that this medication alone is less effective than other treatments for these skin conditions.6,7 In fact, on its own, topical tretinoin is not considered a standard treatment for these conditions.
Bercovitch and co-authors conducted a trial in which all patients with actinic keratosis received 5% 5-FU cream. Half the study participants also received either 0.05% tretinoin to apply or placebo cream.8 The arms treated with both active ingredients had significantly fewer actinic keratosis lesions after three months. It should be noted that this trial was small (19 patients) and other authors have identified potential bias.2
Importantly, published clinical trial has examined the efficacy of using tretinoin pretreatment prior to 5-FU.2 Nevertheless, dermatologists consistently report is in peer-reviewed journal articles that “Thicker, hypertrophic lesions should be treated first with cryosurgery, gentle curettage, or even “primed” with applications of tretinoin cream, lactic acid moisturizers, or short courses of topical diclofenac sodium before the initiation of 5-FU cream,”9 or “[tretinoin] accelerates the penetration of this antimitotic agent [5-FU]” into the lesion.10 In fact, this often-repeated notion that tretinoin is helpful in combination with 5-FU seems to be based on anecdotal evidence rather than clinical trials.2 The data suggests, while it is routinely done, there is no direct evidence that pretreatment with tretinoin cream actually makes topical 5-FU more effective. In fact, there is no clear evidence from clinical trials to support pretreatment with tretinoin prior to any skin condition that requires treatment with topical 5-FU. When you consider topical tretinoin can sometimes be associated with a burning sensation, irritation, redness, and skin inflammation11, patients with thick skin lesions that require softening or priming may consider other options, such as cryosurgery (freezing the lesion) or gentle curettage (scraping or shaving the skin to dislodge the thickened skin).12 Indeed, it seems prudent to discuss other pre-treatment options with your provider before starting pretreatment with topical tretinoin.