Our study aims to evaluate the role of ct-DNA and PBMC as biomarkers in the treatment of biliary tract cancer.

Biliary cancer ranked fifth in all gastrointestinal malignant cancer. Epidemiological surveys showed a significant increasing trend in recent years. How can make an early diagnosis of bile duct cancer as well as prognostic evaluation and efficacy monitoring, has become the hotspot. "liquid biopsy", which is meant to detect cancers by sequencing the DNA in a few drops of a person's blood. It may detect cancers early, even before symptoms arise, when there is just a few cells in the blood circulation.

cf-DNA in cancer patients often bears similar genetic and epigenetic features to the related tumor DNA. There is evidence that some of the cf-DNA originates from tumoral tissue. This, and the fact that cf-DNA can easily be isolated from the circulation and other body fluids of patients, makes it a promising candidate as a non-invasive biomarker of cancer. And we call the cf-DNA of tumor as ct-DNA.

Peripheral blood mononuclear cells (PBMC) is any peripheral blood cell having a round nucleus. These cells can be extracted from whole blood using ficoll, a hydrophilic polysaccharide. PBMC contains genetic material of tumor and may be applied as a biomarker.

This study aims to evaluate the role of ct-DNA and PBMC as biomarkers in the treatment of biliary tract cancer.

Inclusion Criteria:

• Patients with suspected biliary tract cancer
• Age from 18 - 70 years
• No serious organic and mental illness;

Exclusion Criteria:

• Pregnancy
• No pathologic result
• Suffering other malignancies at the same time.

Patients with suspected biliary tract cancer.