This prospective observational study investigates the clinical utility of circulating tumor DNA (ctDNA) in patients with oligometastatic disease (OMD) undergoing definitive-intent local ablative treatment (LAT). The study aims to evaluate ctDNA as a prognostic and response biomarker before, during, and after LAT across cancer types and treatment modalities. Serial plasma samples and archival tumor tissue will be analyzed to assess ctDNA detection rates, elimination patterns, minimal residual disease, and association with recurrence, progression, and survival outcomes.
Oligometastatic disease (OMD) represents an intermediate disease state between localized and polymetastatic cancer and may be amenable to curative or long-term disease-controlling local ablative treatment (LAT). Despite careful patient selection, recurrence rates after LAT remain substantial, highlighting the need for improved biological markers to guide treatment decisions and follow-up. Circulating tumor DNA (ctDNA) is a promising biomarker for prognostication, response assessment, and early detection of recurrence. Pilot studies and systematic reviews conducted by the study group indicate that ctDNA dynamics before and after LAT are associated with treatment outcomes. However, important knowledge gaps remain regarding ctDNA detection rates, elimination patterns, optimal sampling time points, and clinical relevance across metastatic sites, treatment modalities, and oligometastatic states. This prospective observational study, conducted as part of the Pan-Cancer Oligometastatic Biology (POB) project, will enroll patients with oligometastatic solid tumors planned for definitive-intent LAT. Serial blood samples will be collected before treatment, during treatment when applicable, and throughout follow-up. ctDNA and total circulating free DNA will be analyzed using sensitive molecular techniques. Archival tumor tissue will be retrieved for tumor-informed analyses. The study will evaluate ctDNA detection rates, elimination patterns, minimal residual disease, lead time to radiological recurrence, and associations with disease-free survival, progression-free survival, and overall survival. Exploratory analyses of immune-related biomarkers will also be performed. The results are expected to support improved biological stratification and monitoring strategies in oligometastatic disease.
Study Type
OBSERVATIONAL
Enrollment
500
Department of Oncology, Aarhus University Hospital
Aarhus N, Denmark
Association between longitudinal ctDNA status and clinical outcomes after local ablative treatment
Presence and dynamics of circulating tumor DNA (ctDNA) assessed before LAT, after LAT, and during follow-up, and their association with clinically relevant outcomes including radiologically confirmed recurrence or progression, survival status, and lead time to recurrence.
Time frame: During follow-up up to 5 years
Detection rate of ctDNA prior to local ablative treatment
The proportion of patients with detectable circulating tumor DNA in plasma prior to initiation of local ablative treatment will be assessed. Detection rates will be evaluated overall and stratified by treatment modality, cancer type and metastatic site
Time frame: Baseline (pre-LAT)
Elimination patterns of ctDNA following local ablative treatment
Changes in ctDNA levels following local ablative treatment will be analyzed to characterize elimination patterns over time. Changes in ctDNA will be assessed in relation to treatment modality, cancer type, metastatic site, and timing of sampling to evaluate biological response to treatment
Time frame: During follow-up up to 5 years
Correlation between ctDNA and pathological response
ctDNA status and ctDNA changes will be correlated with pathological response
Time frame: During follow-up up to 5 years
Correlation between ctDNA and risk of recurrence or early progression
The association between ctDNA and the subsequent risk of recurrence or early disease progression will be evaluated
Time frame: Up to 5 years
Correlation between ctDNA and disease-free survival or progression-free survival
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Disease-free survival or progression-free survival will be analyzed according to ctDNA status at baseline, post-treatment, and during follow-up to assess the prognostic value of ctDNA in patients treated with definitive-intent local ablative treatment
Time frame: Up to 5 years
Correlation between ctDNA and overall survival
Overall survival will be analyzed according to ctDNA status at baseline, post-treatment, and during follow-up to assess the prognostic value of ctDNA in patients treated with definitive-intent local ablative treatment
Time frame: Up to 5 years
Rate of ctDNA-detected minimal residual disease
The proportion of patients with detectable ctDNA following completion of definitive-intent local ablative treatment, consistent with molecular minimal residual disease, will be determined and analyzed in relation to clinical outcomes
Time frame: up to 5 years
Lead time between ctDNA detection and imaging-confirmed recurrence or progression
The time interval between first detection of ctDNA during follow-up and subsequent radiological confirmation of recurrence or progression will be calculated to estimate the potential lead time provided by ctDNA monitoring
Time frame: During follow-up up to 5 years
Exploratory analysis of total circulating free DNA
Total circulating free DNA levels will be quantified and analyzed exploratorily in relation to treatment, ctDNA status, imaging findings, and clinical outcomes to assess potential additional biological or prognostic value
Time frame: Up to 5 years