Chemotherapy is the use of drugs to destroy cancer cells, usually by ending the cancer cells’ ability to grow and divide.
A chemotherapy regimen, or schedule, usually consists of a specific number of cycles given over a set period of time. A patient may receive 1 drug at a time or a combination of different drugs given at the same time.
Chemotherapy may be given after surgery to eliminate any remaining cancer cells. For some people with rectal cancer, the doctor will give chemotherapy and radiation therapy before surgery to reduce the size of a rectal tumor and reduce the chance of the cancer returning.
Many drugs are approved by the U.S. Food and Drug Administration (FDA) to treat colorectal cancer in the United States. Your doctor may recommend 1 or more of them at different times during treatment. Sometimes these are combined with targeted therapy drugs (see “Targeted therapy” below).
Some common treatment regimens using these drugs include:
Chemotherapy may cause vomiting, nausea, diarrhea, neuropathy, or mouth sores. However, medications to prevent these side effects are available. Because of the way drugs are given, these side effects are less severe than they have been in the past for most patients. In addition, patients may be unusually tired, and there is an increased risk of infection. Neuropathy, which causes tingling or numbness in feet or hands, may also occur with some drugs. Significant hair loss is an uncommon side effect with many of the drugs used to treat colorectal cancer, except irinotecan.
If side effects are particularly difficult, the dose of the drug may be lowered or a treatment session may be postponed. If you are receiving chemotherapy, you should talk with your health care team about any side effects regularly and ask which symptoms and side effects your doctor should know about right away. The side effects from chemotherapy usually go away after treatment is finished.