What is chemotherapy? "Chemotherapy" is a treatment that uses specific drugs to kill any cells (the tiny parts of the body and tumor) which are dividing and growing. These drugs can either be swallowed, put into a vein (one of the tubes that carries blood from one part of the body to another), or sometimes they are put into the fluid surrounding the brain or spinal cord. Chemotherapy drugs have different ways of messing up the control centers of the cell so that they cannot divide and make more of themselves. Hopefully, they fall apart and die. Then body clears away the dead cells. Answered by Dr. Regina Jakacki, pediatric oncologist, Children's Hospital of Pittsburgh July, 2007