Disparities in Survival and Tumor Characteristics in Patients With Single and Multiple Primary Merkel Cell Carcinomas

Supplementary materials for the original article titled “Disparities in Survival and Tumor Characteristics in Patients With Single and Multiple Primary Merkel Cell Carcinomas” Patient Consent: All data were de-identified and publicly available, thus the study was exempt from institutional review board approval and informed consent. Finding: Despite a low prevalence of MPMCC, patients with MCC have a 60-fold increased risk of subsequent MCC compared with the general population.

Second primary MCCs were generally smaller, and mainly diagnosed within five years after the initial MCC. MPMCC was associated with significantly worse overall and cancer-specific survival than SPMCC. These findings suggest that intensified follow-up strategies are warranted for patients with MPMCC to reduce overall and cancer-specific mortality among MCC survivors.