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

Background: The reported efficacy of imiquimod for lentigo maligna varies widely, without consensus on tumor or treatment factors that can impact tumor clearance.

Objective: 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.

Methods: 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.

Results: 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).

Limitations: 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.

Conclusion: Imiquimod offers a 76% histologic and 78% clinical clearance rate for lentigo maligna. Both cumulative dose and treatment intensity affect tumor clearance.