They don't protect the person from infections very well. Instead, these white blood cells fill the bone marrow and make it hard for enough normal blood cells to form. The cancer cells may also move to other parts of the body where they can multiply and build up. The chemotherapy drugs can travel through the blood to the bone marrow. There, the drugs attack the cancer cells.
Radiation therapy is the use of high-energy waves to kill the cancerous cells.
In some cases, kids with leukemia may also need to have surgery to remove the cancer. If the growth of cancer cells can't be controlled with medication and radiation, sometimes the patient will be given much larger amounts of chemotherapy drugs and radiation to kill the cancer cells. But this also kills the normal cells in the person's bone marrow needed to make new blood cells, so the patient is given bone marrow from someone else. This is called a bone marrow transplant , and it helps the patient make new blood cells and, hopefully, get better. For specific medical advice, diagnoses, and treatment, consult your doctor.