Three resurfacing modalities may prevent, delay nonmelanoma skin cancer

Palo Alto, Calif. - The first systematic comparison of CO₂ laser, trichloroacetic acid (TCA) peels and 5 percent fluorouracil (5FU) cream as nonmelanoma skin cancer (NMSC) prophylactics suggests all three may be beneficial, though patients tolerated TCA peels best, says the study's lead author.

Although doctors have used such modalities for this purpose in the past, physicians were left to use their instincts rather than hard data in prescribing them, says Basil M. Hantash, M.D., Ph.D., instructor, dermatology and plastic surgery at Stanford University (he was a dermatology resident at Stanford University, Stanford, Calif., and Veterans Affairs Palo Alto Health Care System[VAPAHCS], Palo Alto, Calif., while working on the study).

Slowing the onset

While it found no significant differences in terms of efficacy, the three modalities were associated with reduction in actinic keratoses (AKs) three months post-procedure, as well as reduced incidence of new NMSCs.

Specifically, researchers note that CO₂ laser resurfacing, TCA peels and 5FU achieved between 83 percent and 90 percent reduction in AKs (P≤ 0.03), a lower incidence of nonmelanoma skin cancer relative to controls (P<0.001) and delayed development of new skin cancers (Arch Dermatol. 2006;142:976-982).

"We were surprised that the three modalities performed comparably. I would have expected that the CO₂ laser would have been the most efficacious," followed by 5FU and TCA peels, Dr. Hantash says.

Nevertheless, he surmises that all three modalities worked equally well because they achieve resurfacing to a similar depth.

By efficiently resurfacing and removing photodamaged skin, Dr. Hantash tells Dermatology Times, "One abrogates the subsequent risk of developing future AKs or precancers, as well as full-fledged squamous or basal cell carcinomas (SCCs, BCCs)."

Study sampling, methods

Researchers selected a total of 34 patients from those evaluated at the VAPAHCS dermatology clinic between October 1, 2000 and October 30, 2002, who had histories of facial or scalp NMSC and numerous AKs or significant photodamage alone.

However, researchers excluded patients who had undergone laser or chemical peel facial resurfacing procedures up to five years before enrolling, as well as those who had undergone topical therapy or liquid nitrogen cryotherapy on the face within two months pre-enrollment.

"Patients who had NMSCs at the time of study entry were usually managed surgically and were excluded as well. We were looking more at the preventive side of things" than how to treat NMSCs once they've developed, Dr. Hantash explains.

Accordingly, researchers charted the number and locations of existing AKs on a diagram of the head at enrollment and throughout the study's 24-month follow-up period. Susan M. Swetter, M.D., associate professor of dermatology at Stanford and VAPAHCS, senior author and study supervisor, confirmed AK diagnoses.

Ultimately, researchers used five of seven eligible patients who declined study-related treatment as controls. They randomized the remaining 27 patients to one of three treatment arms - CO₂ laser skin resurfacing (Ultrapulse, Coherent Inc.), 30 percent TCA (Spectrum Quality Products) peel or full-face treatment with 5FU (Efudex, Valeant Pharmaceuticals).

Researchers performed two passes with the CO₂ laser and gave patients post-procedural medications and detailed skincare instructions that included washing the face three times daily with superfatted, fragrance-free cleanser, soaking treated areas with diluted acetic acid three to four times daily and applying bland hydrophilic ointment until re-epithelialization occurred.

Patients who had undergone TCA resurfacing underwent the same pre-and post-procedure regimen as those treated with CO₂ laser. As for 5FU, patients themselves performed twice-daily application for three weeks as tolerated. They also used a low-potency corticosteroid for one to two weeks after treatment to decrease redness and irritation. Researchers moreover instructed all study patients to apply sunscreen (30 SPF) each morning and 0.05 percent tretinoin cream to the face and scalp nightly.