Prospective Cohort Study on the Determinants of Venous THromboembolic Recurrence

This study is looking at why blood clots (called venous thromboembolism, or VTE) come back in some people and not others. When a blood clot forms in a vein — usually in the leg (deep vein thrombosis) or the lungs (pulmonary embolism) — there is always a risk it could happen again. Researchers want to understand what factors — such as age, lifestyle, medical history, or blood tests — predict who is most likely to have a repeat clot. This is an observational study, meaning researchers will follow participants over time and collect information, but will not change or prescribe any treatments. Participants will be asked questions about their health and may have blood samples taken. The goal is to build a clearer picture of recurrence risk so that doctors can better tailor preventive treatment for each patient. You may be eligible if you: - Are 18 years of age or older (or a minor with parental consent) - Are 50 years old or younger, OR have an active cancer diagnosis at any age - Have been diagnosed with a venous thromboembolic disease (blood clot) - Are affiliated with social security - Are willing to participate You may NOT be eligible if you: - Have difficulty communicating or understanding (comprehension disorder) - Refuse to participate Talk to your doctor to see if this trial is right for you.