We intend to establish an efficient method for plasma cfDNA extraction and Bisulfite transformation to facilitate the detection of DNA methylation status using multiplex fluorescence PCR. Meanwhile, we expect to identify several plasma methylation markers that can be highly sensitive for multi-cancer detection. Finally, we will provide a pan-cancer blood test that is easy to operate, low cost, accurate and easy to promote.

Inclusion Criteria:

- (1)age >= 18 years. (2) with high suspicion of cancer diagnosed by endoscopy, other imaging examinations, pathological examinations, etc.

(3) no treatment with radiotherapy or chemotherapy.

Exclusion Criteria:

• (1) received antineoplastic treatment such as radiation/chemotherapy. (2) not preserved as required. (3) contaminated or volume is insufficient. (4) unclear pathological results (5) incomplete patient information.

200 cases are planned for each cancer type, and the total number of samples in the cancer group is expected to be 2,000.The number of samples in the non-cancer group is expected to be 1000 cases。