The study is going to recruit patients with gastrointestinal cancer, collect clinical data and peripheral blood sample and possible fat samples. The expression of SIRT-6 in peripheral blood will be tested and connect with different status of cachexia of the patients. A mathematical model of the relationship between cachexia classification and SIRT-6 expression is going to constructed as anticipated.

At the start of cancer develop, not all patients with gastrointestinal cancer manifest cachexia, it may be associated with SIRT-6 expression. This study will collect and test the peripheral blood sample of patients, use it as an important indicator of the degree of cachexia, and provide references for clinical drug intervention, prognosis and dietary intervention for cachexia patients. If possible, fat sample of the patients will be collected during surgery, and the adipose progenitor cells will be cultured to find the key target proteins by detecting differences in protein expression, changes in protein modification levels, and protein interactions.

Inclusion Criteria:

1. Age between 18 and 90 years old, unlimited gender;
2. Patients who are diagnosed with gastrointestinal cancer for the first time and are planning to undergo further treatment;
3. Volunteer to participate and sign the informed consent form.

Exclusion Criteria:

1. Women who are pregnant or lactate;
2. Patients with severe metabolic diseases; combined with cardiac function, liver and kidney dysfunction, acute myocardial infarction and acute stroke in the past 3 months , COPD acute onset respiratory failure and other serious medical diseases and patients who need hormone therapy

Patients who are diagnosed with gastrointestinal cancer for the first time without any chemotherapy or radiotherapy