French Assessment of MRD by Liquid Biopsies in Colorectal With Liver Metastasis Patients (FRENCH.MRD.CRLM)

Inclusion Criteria:

* Patient 18 years or older.
* Colorectal cancer liver metastasis or metastases, according to the assessment of the MDT.
* Metachronous and synchronous metastases will be included, as long as treatment intention of metastases resection is curative. In case of rare instances, where the liver metastases is removed before surgery of the primary tumor, postOP ctDNA is collected when the patient is considered completely tumor-free, i.e. after complete surgery of both the liver metastases and the primary tumor.
* Treatment is planned with curative intent (patients treated with RFA can be included, BUT in these cases a tissue sample from the primary CRC tumor is a requisite)

Exclusion Criteria:

* Hereditary colorectal cancer linked to familial colonic polyposis or Lynch syndrome.
* Extrahepatic metastases
* Malignant colorectal polyps diagnosed after polypectomy.
* Synchronous colorectal and non-colorectal cancer diagnosed per operative (except skin cancer other than melanoma)
* Other cancers (excluding colorectal cancer or skin cancer other than melanoma) within 3 years from eligibility screening
* Patients who are unlikely to comply with the protocol (e.g. uncooperative attitude), inability to return for subsequent visits) and/or otherwise considered by the Investigator to be unlikely to complete the study.
* Liver cirrhosis
* CRLM intervention/surgery cannot be/was not performed with curative intent
* No tumor tissue available (preferably CRLM lesion, or alternatively primary tumor)
* Pregnant or nursing woman, or in childbearing age and not willing to use contraception
* Protected and vulnerable adult
* Not covered by Health insurance
* Patient unable to understand and sign written informed consent.