A comparison of invasive squamous cell carcinoma greater than 1 year after treatment with 5-fluorouracil, imiquimod, or photodynamic therapy with aminolevulinic acid.

Abstract

Studies comparing 5-fluorouracil (5-FU), imiquimod, and photodynamic therapy with aminolevulinic acid (PDT-ALA) have evaluated the efficacy of destroying actinic keratosis (AK). However, this end point may not directly translate to cutaneous squamous cell carcinoma (cSCC) prevention. No study to date has evaluated these field therapies for cSCC prevention in the long term, defined as greater than 1-year posttreatment. Determine the time to surgically treat invasive cSCC development after treatment with 5-FU, imiquimod, or PDT-ALA beginning 1-year posttreatment. Retrospective cohort study using the Optum Clinformatics Data Mart database from 2012 to 2019 RESULTS: The rate of cSCC development in patients treated with 5-FU showed no significant difference compared with imiquimod (0.99; 95% CI, 0.90-1.08). PDT-ALA was worse than 5-FU (1.27; 95% CI, 1.19-1.36) and imiquimod (HR, 1.29; 95% CI, 1.17-1.43). Other known predictors of cSCC were consistent with previous literature. The location of field therapy could not be determined with a claims database. 5-FU is not superior to imiquimod beginning 1 year posttreatment, despite previously demonstrated superior AK destruction efficacy, but was superior to PDT-ALA. Conflating AK destruction and cSCC prevention efficacy may not be appropriate. Future prospective studies should aim to use an end point of cSCC development.