Blood biochemical tests cannot detect cancer. Blood biochemical tests are mainly for liver, kidney, heart and electrolyte tests, mainly to check whether there are any abnormalities in the function of these organs and whether there are any diseases, and to make diagnosis and clinical differential diagnosis. Then how to check cancer can be done by screening tumor related markers and specific and targeted screening of tumor related markers according to the clinical manifestations of individual patients, or by doing some related imaging examinations such as ultrasound, CT, MR and other auxiliary examinations, as well as by the clinician’s examination of the patient, in order to check and diagnose cancer or to differential diagnosis.