DANA POINT, CALIF. – Despite significant advances in dermatology in recent years, little progress has been made in reducing actinic keratoses and skin cancers, Dr. Mark G. Rubin said at the SDEF Summit in Aesthetic Medicine.
"The take-home message to me in all this is, don’t get actinic keratoses," said Dr. Rubin, who practices dermatology in Beverly Hills, Calif. "We really don’t have a great therapy, so it’s important for your patients and for yourself that you limit the amount of ultraviolet light that you get, because we don’t have a wonderful treatment option for patients at this point."
Dr. Mark G. Rubin
That message is especially important for immunosuppressed organ transplant patients, who face an incidence of skin cancer 64-250 times higher than that of the general population.
"Immunosuppressed patients grow four times as many squamous cells than basal cells, which is the reverse of the ratio of these cancers in immunocompetent patients," he said. "Those particular tumors are much more aggressive and have a higher incidence of metastasis. Sun protection is tremendously important in these patients."
In a randomized trial of 120 transplant patients, 60 patients applied 2 mg/cm2 of sunscreen with an SPF greater than 50 to the head, neck, forearms, and hands daily for 24 months, while 60 patients in the control group did not apply any sunscreen (Br. J. Derm. 2009;161 [Suppl. 3]:78-84). Both groups of patients had an equal number of AKs at the start of the trial, but at the end of 24 months, 82 new AKs developed in the control group compared with none in the sunscreen treatment group. In addition, eight patients in the control group developed squamous cell carcinoma, compared with none in the sunscreen group, while nine patients in the control group developed basal cell epithelioma, compared with two in the sunscreen group.
While fluorouracil in the form of Efudex 2% and 5%, Fluoroplex 1%, and Carac 0.5% has been a mainstay of AK treatment, imiquimod in the form of Aldara Cream 5% and Zyclara Cream 3.75% "has probably been the most popular recently," said Dr. Rubin, also of the University of California, San Diego. Another treatment option is diclofenac in the form of Solaraze 3%.
"None of these are fun therapies for patients," he said. "It’s hard to get patients to apply 5-FU more than once. They’ll do it once, hate the experience, and ask, ‘What do you have now doc, because I’m never facing that again.’ It’s made some of the other products like Solaraze, Carac, and Aldara more popular because they’re a little less brutal for the patient. But it’s important to realize that any of these products are going to impact your patients’ daily life. They’re all going to cause some redness, swelling, crusting, stinging, and burning that will go on for a period of weeks if not months, depending on the product that you use and the protocol that you follow."
A review of multiple trials suggests that these medical therapies show complete clearing of AKs in 36%-58% of patients within 1-4 months post treatment.
"It’s important to differentiate between reducing the overall bulk of precancer and eradication, or complete clearance," Dr. Rubin added. "You really want to look at complete clearance, because if you just improved it and the keratosis is smaller, 6 months later it will be back and look like you never touched it. Unless you’ve eradicated the lesion, you’re wasting your time."
Systemic retinoids such as Acitretin and Etretinate are another treatment option, yet they are not a long-term solution given their propensity to cause multiple side effects, including chapped lips, dry eyes, headaches, and hyperlipidemia.
"It’s almost unfair to put a patient on these because they’ll love it for awhile, and then you have to take it away, and then they’ll do horribly – unless you’re doing this with a second plan where you put the patient on it for 6 months to stabilize them before moving on to another treatment option, such as photodynamic therapy, which may be reasonable," Dr. Rubin said.
Chemical peels have some value for decreasing AKs in immunocompetent patients, but the results are no better than with topical medications, he said. The deeper the destruction, the better the result.
"Some actinic keratoses and squamous cell in situ go down the hair follicles," Dr. Rubin said. "If you’re not chasing it down the hair follicle you’re leaving the root behind in a lot of these patients, and that’s what creates a lot of these recurrences. Medical therapies are moderately effective if you look at them a couple of months later. But response rates are not wonderful, and the relapse rates are really terrible."