Risk of subsequent cutaneous squamous cell carcinoma in patients with melanoma

Background: Patients with melanoma are at increased risk for cutaneous squamous cell carcinomas (SCCs). Objective: We sought to examine the incidence of subsequent SCC among melanoma survivors and the impact of patient and melanoma characteristics on SCC risk. Methods: Kaiser Permanente Northern California members given the diagnosis of melanoma from 2000 to 2005 (n = 6378) were followed up through 2009 for a pathology-confirmed SCC. Cox models were used to estimate SCC risk. Results: The crude SCC incidence rate was 2.41 per 100 person-years, and was higher among males and older subjects. In adjusted models stratified by age, SCC risk was higher among males (hazard ratio [HR] 1.43, 95% confidence interval [CI] 1.22-1.67), those with history of nonmelanoma skin cancer (HR 2.56, 95% CI 2.19-2.98), and those with higher tumor sequence numbers (HR 1.35, 95% CI 1.01-1.80). SCC risk was lower among non-Hispanic whites (HR 0.39, 95% CI 0.17-0.86). Limitations: SCC risk was not examined among members without melanoma. Conclusions: SCCs arise in approximately 12% of patients with melanoma over a 5-year period and are more common among males, whites, patients older than 60 years, those with prior reportable cancers, and those with history of nonmelanoma skin cancer. Clinicians should be vigilant for SCCs among these individuals at high risk, and counsel melanoma survivors about their increased risk for SCCs.