FAST Supplemental Material

Patients (Fitzpatrick I-III) diagnosed with AKs on the scalp or face were enrolled. FAST is a global assessment scale of actinic damage developed by nationally recognized dermatologists (AJP, ESR, CDS, STA)- FAST 1: evidence of photodamage, but no AK; FAST 2: discrete AK without confluent lesions; FAST 3: confluent AK and/or SCC in situ in a large area and inability to identify discrete lesions (Supplemental Figure 1). Patients with history of field therapy in the past 3 years were excluded. Patients were scored with FAST and medical records were reviewed to determine if patients had a KC in the past 2 years. Associations between FAST stage and skin cancer risk were calculated using Fisher's Exact Test. Odds ratios for these associations were calculated using logistic regression. Analyses were performed in Stata 17.0 (College Station, TX, StataCorp, 2021). See supplement for detailed methodology.