A preliminary study of imiquimod treatment in variants of basal cell carcinoma.

Imiquimod is a topical immune response modifier that has proved efficacious in the treatment of the superficial variant of basal cell carcinoma. The nodular variant of basal cell carcinoma has shown moderate response to imiquimod; other variants have not been tested. The mechanism of action is largely unknown; however, studies indicate the mechanism involves alteration of local cytokine production. The objective of this study is to evaluate the cytokine response of imiquimod in all variants of basal cell carcinoma. Ten patients were selected who had clinically and histologically proven basal cell carcinoma. All lesions were treated with imiquimod once a day, 5 days a week, for 3 weeks. After a 3-week rest period, the lesions were rebiopsied. All biopsy specimens were analyzed via polymerase chain reaction (PCR) for various cytokines. Nine of 10 lesions resolved clinically, which included nodular, superficial, infiltrative, adenoid, and micronodular variants. The cytokine with the greatest change pre- and post-treatment was IL-8, which decreased an average of 44 per cent (P = 0.06). We concluded that topical 5 per cent imiquimod is an effective treatment of various subtypes of basal cell carcinoma. IL-8, which plays an important role in the development and metastasis of melanoma, may be involved in the mechanism of action of imiquimod on cutaneous malignancies. Larger studies are needed to prove the efficacy of imiquimod on nonsuperficial variants of basal cell carcinoma and cutaneous melanoma metastasis.