Medical Dermatology

MONTEREY, CALIF. — Pretreatment with topical imiquimod or 5-fluorouracil appears to improve surgical results in both basal cell and squamous cell carcinoma, Dr. Abel Torres reported at the annual meeting of the Pacific Dermatologic Association.

Published and unpublished studies by Dr. Torres, chief of the division of dermatology at Loma Linda (Calif.) University and his colleagues indicate that these adjunctive treatments can be tissue sparing in Mohs surgery. Furthermore, adjunctive use of imiquimod cream appears to have an immunologic component that may be especially helpful for immunocompromised patients.

These adjunctive uses of 5-fluorouracil (5-FU) and imiquimod are off label, although both agents are labeled for the treatment of actinic keratoses and for superficial basal cell carcinoma (BCC), he noted.

In an open-label series of 40 cases of squamous cell carcinoma (SCC), pretreatment with 5-FU 5% cream twice a day for 3 weeks, followed by Aquaphor for 3 weeks, appeared to be tissue sparing in the subsequent Mohs surgery. In addition, Dr. Torres' reported his clinical impression that there was no greater recurrence rate seen with this pretreatment than he would have expected without it.

The rationale for this treatment is that SCCs often have a superficial component that can be ill defined and difficult to distinguish from actinic keratoses. If one can remove the superficial component prior to surgery, the surgeon can maximize tissue preservation while still ensuring tumor removal.

Dr. Torres said it's important to wait at least 2 weeks after treatment with 5-FU before conducting the surgery. Otherwise, inflammation at histology is likely.

He cautioned that the results of randomized, double-blind, vehicle-controlled studies, which are in the planning stage, will be necessary before it will be possible to recommend this treatment without reservation.

One of the outstanding questions is whether the pretreatment will create "skip areas," essentially turning a unifocal lesion into a multifocal one. Until control data become available, patients should be advised of the innovative nature of this treatment.

Dr. Torres has already published a controlled study of imiquimod 5% cream as an adjunct to Mohs surgery in the treatment of basal cell carcinoma (BCC). Seventy-two patients with superficial or nevoid BCC were randomized to receive either vehicle or imiquimod cream five times a week for 2, 4, or 6 weeks before they underwent Mohs surgery (Dermatol. Surg. 2004;30:1462–9).

Only 6% of the patients receiving placebo showed evidence of histologic clearance. In contrast, two-thirds of patients using of imiquimod had histologic clearance at 4 weeks or 6 weeks, a significant difference. The use of imiquimod also was associated with significant reductions in the size of the tumor and the size of the postsurgical defect.

There was only one skip area among the imiquimod patients, compared with five among placebo patients, a nonsignificant difference.

There was some indication of an immunologic aspect to the imiquimod treatment. For example, Dr. Torres observed that all five of one patient's lesions cleared, although only two were treated, indicating some kind of regional effect.

Dr. Torres concluded that using an immune modulator before surgery may improve outcome by eliminating the need for surgery in some individuals and by reducing the morbidity of the surgery and its cost by decreasing the size of the defect and the complexity of its repair.

The observation that imiquimod may be stimulating a regional immune response suggests that this adjunctive treatment may be especially useful in improving the efficacy of Mohs surgery in immune-compromised patients.

10/01/06  

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