LIquid BIopsies in Patients Presenting Non-small Cell Lung Cancer

This study is looking at whether a simple blood test (called a liquid biopsy) can detect cancer DNA in the bloodstream of patients with advanced non-small cell lung cancer — potentially offering a less invasive alternative to traditional tissue biopsies. **You may be eligible if...** - You have been diagnosed with advanced non-small cell lung cancer (stage IIIB or IV) confirmed by biopsy - You are 18 years of age or older - You are covered by health insurance (in France) - You are willing to sign a consent form - For some groups: your cancer has specific genetic mutations (such as EGFR, BRAF, ALK, or others) or you are starting immunotherapy **You may NOT be eligible if...** - You have already started cancer treatment before your blood (liquid biopsy) sample is taken - You have not yet had a tissue biopsy done Talk to your doctor to see if this trial is right for you.