National report — Daily topical treatment of surgical excision sites with imiquimod 5 percent cream is well-tolerated, but at least in the short-run, it does not appear to have any benefit for enhancing cosmetic outcomes, according to Brian Berman, M.D., Ph.D., professor of dermatology and internal medicine at the University of Miami School of Medicine, Miami.
"The potential for imiquimod to improve cosmesis of postsurgical scars was strongly supported by research detailing its mechanisms of action," he tells Dermatology Times.
"Although the treatment is well-tolerated when applied to sutured surgical wounds and does not increase the risk of wound complications such as infection and dehiscence, imiquimod does cause erythema, and according to the results of our double-blind, randomized, vehicle-controlled study, does not improve cosmesis in the first two months after surgery. Time and further follow-up will tell if this topical agent might offer any benefit for improving final scar appearance," Dr. Berman says.
Interest in using imiquimod to modulate wound healing is based on knowledge that it induces local synthesis of interferons that have antifibrotic activity. In a study conducted several years ago, Dr. Berman and colleagues from the department of dermatology & cutaneous surgery demonstrated that postsurgical application of imiquimod cream nightly for eight weeks reduces the risk of recurrent scarring after keloid removal (J Am Acad Dermatol. 2002;47(4 suppl):S209-11).
Recognizing that keloids represent a very difficult model of scarring, they were interested in exploring a role of imiquimod for improving the cosmetic outcome in less challenging wound healing situations. Results of a pilot study found the topical immune response modifier was safe and well-tolerated when applied to surgical excision sites in patients not prone to keloid formation. Consequently, the present trial was undertaken to evaluate the potential of imiquimod to improve surgical scar appearance.
The study enrolled 20 patients, each undergoing surgical excision of two melanocytic nevi, who applied measured amounts of imiquimod cream to one surgical wound site and of vehicle cream to the other randomly selected lesion nightly for four weeks. Eligible patients had to have two nevi being excised from a similar anatomic area of skin. With one or two exceptions, all of the nevi were removed from the back.
The surgical wounds were closed primarily and treatment began on the first postoperative night. Sutures were removed after two weeks.
Parameters of scar appearance, including investigator and patient-assessed overall cosmesis, erythema, pigmentation and induration, were rated using a visual analogue scale at two, four and eight weeks. Eighteen patients were seen after eight weeks and while follow-up beyond that visit was not required, ten patients were seen at least once between 17 and 46 weeks postoperatively.
In all endpoints at eight weeks, the scores were consistently numerically worse for the imiquimod-treated excision sites, and statistically significant differences favoring vehicle treatment over imiquimod were seen in all investigator-rated assessments except induration.
Thereafter, scores for cosmesis, erythema and induration improved for both treatments, although pigmentary alterations worsened. Scores continued to be worse for imiquimod treatment and mean scores for visits occurring between 17 to 26 weeks post-op showed statistically significant differences favoring the vehicle-treated sites in both the investigator and patient ratings of scar cosmesis.
No significant between-treatment differences were noted when analyzing the data for the limited number of evaluations made between weeks 39 to 46.
Dr. Berman notes that in a very recently published study, topical imiquimod treatment was found to improve the appearance of breast surgery scars when evaluations were performed after 24 weeks (Prado A, et al. Plast Reconst Surgery 2005;115:967-971). The breast surgery scar trial had a prospective, blinded, bilateral, controlled design.