Chemotherapy consists of drugs that are given either by mouth, a shot, or an IV line (intra-venous; into a vein). These drugs are cytotoxic (cell-killing).
There are different phases of the life cycle of a cell. All cells divide, but cancer cells divide abnormally or more quickly. The drugs used in chemotherapy aim to destroy dividing cells. The goal is that, since cancer cells are more actively dividing, these cells will be killed. At the same time, since some normal cells will also be in the dividing phase, they too will be destroyed. This is why patients can experience side effects.
Some side effects can include nausea and vomiting, loss of appetite, hair loss, mouth sores, loose stool, bruising or bleeding, infections, fatigue, shortness of breath, weakness, or numbness. Many of these go away after treatment is over. Your oncologist will help you manage these problems if they occur.
Chemotherapy is given at regular intervals called cycles. This approach allows normal cells time to recover from the side effects. The schedule and numbers of cycles are determined by the type and stage of the cancer, and how the particular drug that is used works best.
Chemotherapy is often given before or after surgery. When given before surgery, it is called neo-adjuvant, and when given after surgery, it is called adjuvant. Neo-adjuvant chemotherapy aims to shrink a cancerous tumor, and adjuvant chemotherapy aims to stop the growth of any remaining cancer cells. In either case, the purpose of chemotherapy used in this way is to help maximize the effectiveness of the surgery.
In recent years, chemotherapy regimens have been developed that are better tolerated by patients, and most patients no longer experience horrible side effects and a miserable life style as a result of their treatment. A bad experience with "chemo" is considered a thing of the past.