Abstract
BACKGROUND: Many patients will develop more than one skin cancer; however, most research to date has examined only case status. OBJECTIVE: Describe the frequency and timing of the treatment of multiple skin cancers in individual patients over time. METHODS: We conducted a longitudinal claims and electronic health record-based cohort study to examine the frequency of skin cancer multiplicity. We used a validated phenotype for counting individual skin cancers. RESULTS: Our combined cohort included 5,508,374 patients and 13,102,123 total skin cancers treated. Forty-three percent of patients treated for skin cancer were treated for more than one skin cancer, most within 2 years of the initial skin cancer. A subset of 3% of patients were treated for 10 or more skin cancers and contributed 22% of all skin cancers treated in the combined cohort. LIMITATIONS: High-quality data on skin cancer types were not available. Databases and health records are not designed to capture skin cancer multiplicity well. CONCLUSIONS: Nearly half of patients treated for skin cancer will develop at least one more. Better data formatting will allow for improved granularity in identifying individuals at high risk for multiple skin cancers and those unlikely to benefit from continued annual surveillance.