Cancer can present with elevated white blood cells. Cancer does not elevate white blood cells under normal conditions, or they are markedly elevated. Once white blood cells are markedly elevated, it is often indicative of an infection or secondary leukemia-like reaction. Cancer is a malignant tumor that may lead to elevated white blood cells with cancer treatment. The cause of elevated white blood cells is due to antibodies produced by the body’s functions. Some hormonal chemotherapeutic drugs can also cause elevated white blood cells during treatment. White blood cells are also elevated when the cancer is infected or when there is a secondary inflammatory response. High white blood cells in cancer patients with concomitant infections, or with hematologic disorders, need to be analyzed based on accompanying symptoms. If there is a blood system disease, it is necessary to clarify the type of the specific disease, and then treat the primary disease to control the condition. After the elevation of white blood cells in cancer, it is necessary to go to the hospital for treatment in time to avoid the spread and metastasis of the disease.