Cancer cannot be diagnosed by any of the routine blood tests. Routine blood tests mainly include red blood cell, hemoglobin, white blood cell and white blood cell classification count, red blood cell specific volume and platelet. According to red blood cell count and hemoglobin concentration, anemia can be diagnosed; according to white blood cell count and classification, viral infection or bacterial infection can be initially judged; abnormally elevated white blood cells and suspicion of leukemia require bone marrow aspiration; according to platelet count, thrombocytosis, thrombocytopenia and leukopenia can be diagnosed. Cancer screening can be done through lab tests for tumor markers and imaging tests. However, a definitive diagnosis of cancer usually requires histopathologic testing. Pathology is the gold standard for cancer diagnosis and can be used to screen for tumors through some simple exfoliative cytology, scraping methods, puncture, and tissue excision pathology. Abnormalities in routine blood tests are recommended to be interpreted by a doctor and not to be judged blindly by oneself. Suspected cancer, need to go to the hospital under the guidance of a doctor to confirm the diagnosis.