Combination Topical Chemotherapy for the Treatment of an Invasive Cutaneous Squamous Cell Carcinoma

Introduction: Standard of care for squamous cell carcinoma (SCC) is usually surgical, with either excision or Mohs micrographic surgery. However, surgery may not be ideal for elderly patients with numerous lesions, who are poor surgical candidates or who refuse surgery. Topical 5-fluorouracil (5-FU) and imiquimod have been studied off-label as monotherapies in the treatment of SCC in situ with promising results. However, long-term tumor-free survival rates are still less than with surgical management. Methods: We report a case of biopsy-proven invasive SCC in an 86-year-old Caucasian male with history of multiple actinic keratoses and no previous skin cancers. The patient declined surgical treatment due to concerns about cosmetic outcomes. A combination of topical 5% imiquimod cream, 2% 5-FU solution, and 0.1% tretinoin cream was used five nights per week under occlusion for a treatment goal of 30 total applications. The patient was evaluated in clinic every 2 weeks during which the site was treated with cryotherapy. The patient reported burning pain associated with treatment and only completed 24 of the 30 applications. Results: Follow-up biopsy 15 months after completing topical treatment revealed dermal scar with no evidence of residual carcinoma. Conclusion: Topical combination therapy with imiquimod, 5-FU, and tretinoin with intermittent, brief cryotherapy effectively treated a small, invasive SCC in this select patient who deferred surgery. Prospective randomized-controlled clinical trials to assess the role of combination topical treatment for invasive SCCs are warranted. J Drugs Dermatol. 2020;19(2)202-204. doi:10.36849/JDD.2020.2228