Reasons for Patient Call-backs while being Treated with Topical 5-fluorouracil: A Retrospective Chart Review.

Objective: To assess the frequency and character of adverse events (AE) associated with 5-FU and compare rate of these events to topical tacrolimus, another irritating topical treatment, as a control.

Methods: Patients prescribed 5-FU for Actinic keratosis (AK) between 1/2015 to 10/2021 were contacted via phone to assess frequency of AE and why they did or did not contact their dermatologist via retrospective chart review. A similar retrospective chart review was done for patients prescribed topical tacrolimus between 1/2015 to 10/2021.

Results: Participants frequently reported AE with 5-FU treatment (58%), which most commonly included redness or inflammation (38%) and burning, stinging, or pain (27%). There were 33 call backs for 5-FU (37 distinct questions) and the most common reasons included issues obtaining the medication (n=12) and inquiries about severe LSR (n=11). There were two call backs for topical tacrolimus related to issues obtaining the medication.

Limitations: Topical tacrolimus as a control helps address the lack of objective assessment of AE severity and potential recall bias limitations of the study methodology.

Conlcusion: Participants in our cohort frequently reported AE, and those who reported AE often contacted their dermatologist. The irritation induced by 5-FU is of greater severity compared to topical tacrolimus, as evidenced by much greater call-back rate. Addressing the risks and benefits of 5-FU, severity of LSR, and use of alternative treatments may improve AK treatment outcomes.