Chemotherapy is a term used to describe several different treatments for cancer that are done by giving high doses of medications or radiation therapy to people who have cancer. These treatments are typically given after other medical procedures have removed or helped as much as possible to remove the tumor. Chemotherapy can also be used to try and prevent a person from getting cancer in the future. The word chemotherapy was chosen because it sounds like something that would help you feel better when you have a cold.The name is not, however, a reflection of how the treatment works.
Chemotherapy is also called chemo or TC (chemo-therapy). Some medicines may also be called chemotherapy when they are given in combination with other therapies such as radiation therapy and surgery. They may also be used alone without other therapy if the cancer has spread to other parts of the body where it might not respond to surgery or radiation therapy. Chemo can also lower the chances that a person will get cancer again after it has been treated. Chemo may be given before or after surgery, radiation therapy, and/or biological therapy. Biological therapies are treatments that use substances made in the body's cells or made in a lab to help fight cancer.
Chemotherapy is usually given as a single course, but it may be used in an alternating or continuous fashion. In some cases, chemotherapy is used to try and prevent a person from getting cancer in the first place and this is called chemoprevention. Chemoprevention can be done before a person gets cancer if he or she has no symptoms but does have an increased risk of getting cancer (such as people with certain genetic mutations who carry the BRCA1 or BRCA2 gene). These treatments are still being studied for their effect on preventing cancer.
Some types of chemotherapy may also be given through a blood transfusion. This is called a peripheral blood stem cell rescue. High doses of chemotherapy are given that often kill most or all of the cells in the bone marrow. This causes a low blood count and low platelet count, which can make a person more likely to get infections. Stem cells from the bone marrow may then be put into the person's bloodstream to help make red blood cells, white blood cells and platelets for a period of time while the chemotherapy courses through, until the new cells in the bone marrow take over production of these cells again.
Chemotherapy and radiation work by killing tumor cells. But the treatments, which are designed to kill everything living in an area, also kill healthy cells. Radiation can damage the DNA of healthy cells in a person's body, which can lead to various forms of cancer later on in life.
The future may be a little brighter than it used to be though. There is evidence that targeted therapies may be more effective for treating cancer by treating only the unhealthy parts of a person's body rather than using chemotherapy or radiation treatments that are damaging to all parts of the body and sometimes cause side effects such as hair loss, nausea, fatigue and diarrhea.
Scientists in Canada have been looking at a class of compounds that protect healthy cells from radiation. These compounds, known as NAD precursors, protect not just the nucleus of a cell but also the mitochondria. The DNA in mitochondria is particularly damaging to healthy cells and can become mutated over time to cause cancer. These NAD precursors are also ways to repair the DNA damage created by chemotherapy and radiation treatments.