A quantitative systematic review of the efficacy of imiquimod monotherapy for lentigo maligna and an analysis of factors that affect tumor clearance.

Abstract

The reported efficacy of imiquimod for lentigo maligna varies widely, without consensus on tumor or treatment factors that can impact tumor clearance. We sought to provide a more precise estimate of clearance rates in patients with lentigo maligna who are treated with imiquimod and to analyze factors that can impact tumor clearance. We performed a literature search for biopsy-proven lentigo maligna treated with imiquimod monotherapy, linked treatment and outcome data to individual tumors, calculated histologic and clinical clearance rates with 95% confidence intervals (CIs), and analyzed the impact of tumor and treatment factors on tumor clearance using logistic regression. Based on 347 tumors from 45 studies, histologic and clinical clearance rates were 76.2% (95% CI, 71.4-81.0%) and 78.3% (95% CI, 73.6-82.9%), respectively. The incidence of clinical recurrence was 2.3% (95% CI, 0.5-4.2%), with a mean follow-up of 34.2 ± 11.8 months. Treatment with >60 total applications, or with >5 applications per week was associated with a higher likelihood of histologic clearance (odds ratio, 8.4 [95% CI, 2.9-24.1] and odds ratio, 6.0 [95% CI, 2.4-14.7], respectively). Our limitations included the accuracy and scope of published data, variable follow-up times, potential patient selection, and publication bias related to case series/cohort designs of previous studies. Imiquimod offers a 76% histologic and 78% clinical clearance rate for lentigo maligna. Both cumulative dose and treatment intensity affect tumor clearance.