WEDNESDAY, Jan. 21, 2026 (HealthDay News) -- Circulating tumor DNA (ctDNA) can detect Merkel cell carcinoma (MCC) recurrence, according to a study published in the February issue of the Journal of the American Academy of Dermatology.

Tomoko Akaike, M.D., from the University of Washington in Seattle, and colleagues examined the timing and prognostic significance of ctDNA levels relative to clinical recurrence in a multicenter prospective study of 669 tumor-informed ctDNA tests from 215 MCC patients with stage I to IV MCC, without clinically evident disease after treatment.

The researchers found that compared with ctDNA-negative patients, patients with at least one positive ctDNA test were more likely to experience recurrence (hazard ratio, 18.1); by one year, 77 percent developed clinically evident disease. Between the first positive ctDNA test and clinical recurrence, the median lead time was 2.7 months. Clinical recurrences usually occurred within three months, within six months, and within nine months for ctDNA levels above 10 molecules/mL, between 1 and 10 molecules/mL, and below 1 molecule/mL, respectively.

"Understanding the lead time between the first ctDNA positivity and clinical recurrence can help tailor follow-up frequency and urgency, optimizing patient-specific care," the authors write. "This approach offers an opportunity to de-escalate imaging frequency for ctDNA-negative patients, reducing unnecessary interventions while maintaining vigilance in higher-risk individuals."

Abstract/Full Text