Multicenter cohort study of ctDNA versus Merkel virus antibody for detecting Merkel cell carcinoma recurrence

Merkel cell carcinoma (MCC) is associated with a high recurrence rate of 40%. Two blood-based biomarkers for detecting MCC recurrence are available: circulating tumor DNA (ctDNA) and MCC polyomavirus (MCPyV) oncoprotein antibody test. A cohort study at 3 US academic centers compared the performance of these tests for detecting MCC recurrence during surveillance. In this cohort study of 169 patients with a total of 703 paired tests, a positive ctDNA result was more predictive of recurrence than antibody testing, with consistently higher positive predictive value (73% versus 52% at 365 days) and negative predictive value (99% versus 97% at 90 days). The authors conclude that ctDNA outperforms antibody testing for detecting recurrence of MCC.