The existing basic research and the latest literature reports do not support the proposed protocol, therefore, the project is withdrawn.

This study aims to evaluate the early diagnosis value of G-quadruplex DNA methylation in patients with cancer.

Global DNA hypomethylation is a hallmark of most cancers that occurs early during oncogenesis. We would like to investigate whether cancer-specific transcription factor binding to DNA G-quadruplex drives DNA hypomethylation in cancer. In this observational study, we would like to clarify whether DNA hypomethylation around G-quadruplex loci in cell-free DNA could be detected in early-stage cancer patients from healthy donors with high sensitivity and specificity.

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.

Healthy volunteers, aged 42 years or older, who are asymptomatic as determined by medical examination and willing to participate voluntarily in the study with signed informed consent.