Imiquimod 5% cream in the treatment of Bowen's disease

Background: Large-diameter lesions of Bowen's disease at sites such as the shin may be difficult to treat surgically and may require alternate treatme nt modalities. Objective: We investigated whether imiquimod 5% cream, a topical immune res ponse modifier that stimulates the production of interferon alfa and other cytokines, is an effective topical treatment for Bowen's disease. Methods: This was a phase II, open-label study in 16 patients, treating a s ingle biopsy-proven plaque of Bowen's disease that was 1 cm or larger in di ameter, with once-daily self-application of imiquimod 5% cream For 16 weeks . A biopsy was performed on the treated area 6 weeks after the end of treat ment, with patient follow-up at 3 and 6 months. Lymphocyte CD4/CD8 ratios w ere analyzed in pretreatment and posttreatment biopsy specimens by immunoph enotyping the lymphocytic infiltrate. Results: Sixteen patients with Bowen`s disease lesions ranging from 1 to 5. 4 cm in cliamctcr (0.7-21.6 cm(2) in area) were treated. Fifteen of these l esions were on the legs, and one was on the shoulder. Fourteen of the 15 pa tients (93% per protocol analysis) had no residual tumor present in their 6 -week posttreatment biopsy specimens. One patient died of unrelated intercu rrent illness before a biopsy specimen could be obtained. The median CD4/CD 8 lymphocyte ratio in pretreatment biopsy specimens was 2:1, and this was r eversed to a median of 1:2.2 in the posttreatment specimens. Ten patients c ompleted 16 weeks of treatment, but 6 patients ceased treatment early (betw een 4 and 8 weeks) because of local skill reactions. Conclusion: Imiquimod 5% cream appears to be an effective treatment for Bow en's disease on the lower limbs. The 93% positive treatment response in bio psy-proven cases (excludes patient who died from an intercurrent illness wh o did not undergo a posttreatment biopsy) compares favorably with other cur rent treatment modalities. The dosing schedule and length of treatment fur Bowen's disease require further evaluation.