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Updated: Jul 18, 2026
Adaptation of Semiautomated Circulating Tumor Cell CTC Assays for Clinical and Preclinical Research Applications
Published on: February 28, 2014
Circulating tumor DNA level is associated with time to clinical recurrence in Merkel cell carcinoma: Implications for
Tomoko Akaike1, Manisha Thakuria2, Ann W Silk3
1University of Washington, Seattle, Washington; Fred Hutchinson Cancer Center, Seattle, Washington.
Background:
Merkel cell carcinoma (MCC) recurs in 40% of patients. Circulating tumor DNA (ctDNA) is an emerging blood-based biomarker for early MCC recurrence detection.
Objective:
To evaluate the timing and prognostic significance of ctDNA levels relative to clinical recurrence.
Methods:
This multicenter prospective study analyzed 669 tumor-informed ctDNA tests from 215 MCC patients (stage I-IV) without clinically evident disease after treatment.
Results:
Patients with at least 1 positive ctDNA test were more likely to experience recurrence compared to ctDNA-negative patients (hazard ratio: 18.1, 95% CI: 8.9-36.7), with 77% developing clinically evident disease by 1 year. The median lead time between the first positive ctDNA and clinical recurrence was 2.7 months. Clinical recurrences usually occurred within 3 months for ctDNA levels above 10 molecules/mL, within 6 months for levels between 1-10 molecules/mL, and within 9 months for levels below 1 molecule/mL.
Limitations:
In this real-world study, there was variability in timing and frequency of follow-up examinations, imaging, and ctDNA testing, although most patients were followed with both ctDNA and imaging.
Conclusions:
A positive ctDNA test detects MCC recurrence approximately 3 months earlier than imaging. Negative ctDNA can help reduce imaging frequency through serial ctDNA monitoring, while positive ctDNA warrants closer patient follow-up.
