Detection of G-quadruplex DNA Methylation in Cancer

Inclusion Criteria: * Healthy volunteers identified as asymptomatic during medical examination; * Age≥42 years old; * Voluntarily participate in this study and sign the informed consent. Exclusion Criteria: * History of malignancy or having achieved complete remission following tumor surgery; * Certain autoimmune diseases (e.g., systemic lupus erythematosus, Sjögren's syndrome, antiphospholipid syndrome, rheumatoid arthritis, Crohn's disease, IgA nephropathy, myasthenia gravis, dermatomyositis, immune thrombocytopenic purpura, etc.); * Pregnancy; * Acute trauma (including surgical procedures), sudden onset organ failure (e.g., resulting from a car accident, fulminant hepatic failure, acute pancreatitis, severe pneumonia due to influenza virus), or diagnosis of sepsis; * Previous receipt of allogeneic blood transfusion, transplant surgery, or allogeneic cell therapy; * Volunteers who cannot provide informed consent.