Chemotherapy is the use of drugs to destroy cancer cells. It works by keeping the cancer cells from growing and dividing to make more cells. Because cancer cells usually grow and divide faster than healthy cells, chemotherapy destroys them more quickly than it destroys most healthy cells.
Since chemotherapy drugs are powerful, they cause damage to many growing cells, including some healthy cells. This damage causes the side effects of chemotherapy.
Different types of chemotherapy
Chemotherapy with these powerful drugs is called standard chemotherapy, traditional chemotherapy, or cytotoxic chemotherapy. Several other types of drugs also treat cancer. Many of the newer drugs are called targeted drugs, because they damage cancer cells by blocking genes or proteins found in the cancer cells. Because these treatments work specifically on the cancer cells, they cause different side effects and usually damage healthy cells less. Other types of cancer therapy include hormones and drugs that work with your immune system to fight cancer.
How does chemotherapy treat cancer?
Doctors use chemotherapy in different ways at different times. These include:
- Before surgery or radiation therapy to shrink tumors—doctors call this neoadjuvant chemotherapy.
- After surgery or radiation therapy to kill any remaining cancer cells—doctors call this adjuvant chemotherapy.
- As the only treatment—for example, to treat cancers of the blood or lymph system. These include leukemia and lymphoma.
- For cancer that comes back after treatment, called recurrent cancer
- For cancer that spreads to other parts of the body, called metastatic cancer
The goals of chemotherapy
Chemotherapy goals depend on the type of cancer and how far it has spread. Sometimes, the main goal is to get rid of all the cancer and keep it from coming back. If this is not possible, you might have chemotherapy to delay or slow down cancer growth.
When chemotherapy delays or slows cancer growth, there are also fewer symptoms caused by the cancer. Chemotherapy given with the goal of delaying cancer growth is sometimes called palliative chemotherapy.
Your chemotherapy plan
There are many cancer drugs available. A doctor who specializes in treating cancer with medication, called a medical oncologist, will prescribe your chemotherapy. You may get a combination of drugs, because this sometimes works better than one drug alone.
Your chemotherapy drugs, dose, and treatment schedule depends on many factors. These include:
- The type of cancer
- The tumor size, its location and if it has spread—doctors call this the stage of cancer.
- Your age and general health
- How well you can cope with certain side effects
- Any other medical conditions you have
- Previous cancer treatments
Where is chemotherapy given?
You can get chemotherapy at a clinic, doctor’s office, or the hospital. You might take the drugs at home with some types of treatment.
How long does chemotherapy take?
You might get chemotherapy for a specific time, such as 6 months or a year. Or you might get it as long as it works.
Side effects from many traditional chemotherapy drugs are too severe to give treatment every day. Doctors usually give these drugs with breaks, so you have time to rest and recover before the next treatment. This lets your healthy cells heal.
For example, you might get a dose of chemotherapy on the first day and then have 3 weeks of recovery time before repeating the treatment. Each 3-week period is called a treatment cycle. Several cycles make up a course of chemotherapy. A course usually lasts 3 months or more.
Doctors treat some cancers with less recovery time between cycles. They call this a dose-dense schedule. It can make chemotherapy more effective against some cancers. But it also increases the risk of side effects. Talk with your doctor about the best schedule for you.