Circulating Tumor DNA (ctDNA)

The goal of this observational study is to investigate whether circulating tumor-derived DNA (ctDNA) can be reliably detected and analyzed in blood obtained through automated capillary sampling in adult patients (≥21 years) with colorectal liver metastases (CRLM). The main question it aims to answer is: * Can ctDNA be detected in small volumes of capillary blood collected using an automated sampling device? * Do ctDNA levels measured in capillary blood agree with those measured in venous blood from the same patients? Researchers will compare ctDNA measurements from capillary blood to those from venous blood (reference standard) to see if capillary sampling provides reliable results for ctDNA analysis. Participants will: * Provide a small blood sample through automated capillary collection. * Provide a venous blood sample during the same study visit for comparison.