Lynch syndrome is an inherited genetic predisposition that increases the risk of developing several types of cancer, particularly colon and rectal cancers (colorectal cancer), as well as cancer of the uterine lining (endometrial cancer). It affects around 1 in 400 people in Europe.

Today, surveillance mainly relies on examinations such as colonoscopy (an examination of the colon using a camera) or gynaecological evaluations, sometimes accompanied by biopsies (the removal of a small tissue sample for microscopic analysis). Although effective, these procedures are invasive and demanding; they can affect quality of life and discourage some individuals from adhering to their recommended surveillance programme.

The European project PREDI-LYNCH is exploring an additional pathway that is simpler and better tolerated. This project relies on "liquid biopsies", meaning tests performed on easily collected samples such as blood, urine, stool, and vaginal swabs for women with a uterus. The PREDI-LYNCH study aims to determine whether these non-invasive tests could enable personalised surveillance and potentially increase the interval between more burdensome procedures, while maintaining a high level of medical safety.

This European clinical study evaluates whether non-invasive liquid biopsy tests (blood, urine, stool and vaginal samples when applicable) can improve cancer surveillance in adults with genetically confirmed Lynch syndrome (MLH1, MSH2, MSH6 or EPCAM). The trial compares two strategies: standard follow-up with colonoscopy every 18 months versus an approach combining annual liquid biopsies with a colonoscopy every 36 months. The main outcome is the number of new cancer cases diagnosed, confirmed by standard procedures. Secondary outcomes include early cancer detection, lesion identification, diagnostic timing, feasibility, quality of life and healthcare use. Each positive test leads to fast confirmatory exams. The aim is to determine if liquid biopsies can safely reduce invasive procedures while maintaining effective cancer monitoring.

Inclusion Criteria:

1. Participant must have signed a written informed consent prior to any trial specific procedures. When the patient is physically unable to give their written consent, a trusted person of their choice, independent from the investigator or the sponsor, can confirm in writing the patient's consent.
2. Age 35-80
3. Genetically confirmed class 4-5 (likely pathogenic (LP) or pathogenic (P) variant, respectively) in MLH1, MSH2, MSH6, or EPCAM gene.
4. The participant should be insurance covered for the financial costs of the standard surveillance and healthcare related to LS, such as affiliated to Social Security System

Exclusion Criteria:

1. Previously performed proctocolectomy or equivalent (entire colon and rectum removed)
2. Active treatment for cancer within 2 years prior to inclusion.
3. Checkpoint inhibitor therapy within 12 months
4. Pregnancy
5. Participants unwilling or unable to comply with the medical follow-up required by the trial because of geographic, familial, social, or psychological reasons.
6. Persons deprived of their liberty or under protective custody or guardianship.