What is Chemotherapy?

Aprobado por la Junta Editorial de Cancer.Net, 05/2022

Chemotherapy is the use of drugs to destroy cancer cells. This type of cancer treatment works by keeping cancer cells from growing, dividing, and making more cells.

Chemotherapy can be used as a treatment for many different cancers. Your doctor may refer to chemotherapy as standard chemotherapy, traditional chemotherapy, or cytotoxic chemotherapy.

This article will help you understand basic information about chemotherapy. Learn more in other articles about what to expect when getting your chemotherapy treatments and the possible side effects of chemotherapy.

How does chemotherapy treat cancer?

Chemotherapy is a systemic medication. This means it travels through the bloodstream and reaches all parts of the body.

There are many different kinds of chemotherapy. In general, drugs used for chemotherapy are powerful chemicals that treat cancer by attacking cells during specific parts of the cell cycle. All cells go through the cell cycle, which is how new cells are made. Cancer cells go through this process faster than normal cells, so chemotherapy has more of an effect on these fast-growing cells.

Because chemotherapy travels through the whole body, it can also damage healthy cells as they go through their normal cell cycle. This is why chemotherapy can cause side effects like hair loss and nausea.

What are the goals of chemotherapy?

The goals of chemotherapy depend on your type of cancer and how far it has spread. Chemotherapy can be given alone or as a part of a treatment plan that includes different treatments. Some of the ways chemotherapy is used include:

As the primary treatment. Sometimes, the goal of chemotherapy treatment is to get rid of all the cancer and keep it from coming back. This might be called "curative chemotherapy."

Before other treatments. Chemotherapy can be given before surgery or radiation therapy to shrink tumors. This can be called "neoadjuvant chemotherapy."

After other treatments. Chemotherapy can be given after surgery or radiation therapy to destroy any remaining cancer cells. This is called "adjuvant chemotherapy."

To slow the progression of cancer and relieve symptoms. Even when the cancer is not curable, chemotherapy can partially shrink tumors and prevent tumor growth and spread for various lengths of time. In such settings, chemotherapy can extend survival, relieve cancer-related symptoms, and improve quality of life. Chemotherapy used for these purposes is sometimes called "palliative chemotherapy."

Chemotherapy can be used to treat many types of cancers. It can also be used to treat recurrent cancer and metastatic cancer. Recurrent cancer is cancer that comes back after treatment. Metastatic cancer is cancer that has spread to other parts of the body.

What factors determine a chemotherapy plan?

There are many drugs available to treat cancer. A doctor who specializes in treating cancer with medication is called a medical oncologist. This type of doctor will prescribe your chemotherapy. You may receive a combination of drugs, because this sometimes works better than 1 drug by itself.

The drugs, dose, and treatment schedule depend on many factors. These include:

  • The type of cancer

  • The stage of the cancer. Cancer stage is determined by the size and location of the tumor and whether or not the cancer has spread. tumor size, its location, and if or where it has spread.

  • Your age and general health

  • Your body weight

  • The possible side effects of each drug. If a drug causes you to have too many side effects, this can also change your treatment plan.

  • Any other medical conditions you have

  • Previous cancer treatments

Where do you receive chemotherapy?

Chemotherapy can be given at a medical center or taken at home, depending on the specific drug.

Your health care team may need you to come in regularly to the clinic, doctor's office, or hospital to receive the chemotherapy. This may be called outpatient treatment.

Some types of chemotherapy can be taken at home. Ask your health care team how to safely store, handle, and dispose of your at-home medication. See more below, under "oral chemotherapy" and "topical chemotherapy."

Learn more about what to expect when getting chemotherapy.

How is chemotherapy delivered?

Chemotherapy may be given in several different ways, which are discussed below.

Intravenous (IV) chemotherapy. Many drugs require injection directly into a vein. This is called intravenous or IV chemotherapy. Treatment takes a few minutes to a few hours. Some IV drugs work better if you get them over a few days or weeks. You take them through a small pump you wear or carry. This is called continuous infusion chemotherapy.

Oral chemotherapy. Oral chemotherapy is taken by mouth. This can be as a pill, capsule, or liquid. This means that you may be able to pick up your medication at the pharmacy and take it at home. Oral treatments for cancer are now more common. Some of these drugs are given daily, and others are given less often. Be sure to ask your health care team about your drug's schedule and how to store the drug. Learn more about how to keep track of taking your medication at home.

Injected chemotherapy. This is when you receive chemotherapy as a shot. The shot may be given in a muscle or injected under the skin. You may receive these shots in the arm, leg, or abdomen. Abdomen is the medical word for your belly.

Chemotherapy into an artery. An artery is a blood vessel that carries blood from your heart to another part of your body. Sometimes chemotherapy is injected into an artery that goes directly to the cancer. This is called intra-arterial or IA chemotherapy.

Chemotherapy into the peritoneum or abdomen. For some cancers, medication might be placed directly in your abdomen. This type of treatment works for cancers involving the peritoneum. The peritoneum covers the surface of the inside of the abdomen and surrounds the intestines, liver, and stomach. Ovarian cancer is one type of cancer that frequently spreads to the peritoneum.

Topical chemotherapy. Some types of chemotherapy come as a cream that you put on your skin. You get your medication at the pharmacy and apply it at home.

What types of chemotherapy are there?

Chemotherapy for cancer includes more than a 100 different drugs. Although all chemotherapy drugs damage cells, they attack different cell targets at different times during the cell cycle. Combining drugs that damage the cancer cell in different ways can increase how well the treatment works.

Below are the main types of chemotherapy:

  • Alkylating agents

  • Antimetabolites

  • Anti-tumor antibiotics

  • Topoisomerase inhibitors

  • Mitotic inhibitors

  • Plant alkaloids

Chemotherapy in combination with other cancer treatments

There are other types of drugs besides chemotherapy that also treat cancer, such as hormone therapy, immunotherapy, and targeted therapy. Sometimes oncologists use chemotherapy alongside another type of drug in a person's treatment plan. These categories of drugs work in different ways to treat cancer, and their side effects are usually different than chemotherapy. Talk with your health care team about what to expect with your specific prescriptions.

Hormone therapy. Hormone therapy is a type of cancer treatment that removes, blocks, or adds specific hormones to the body. It is also called hormonal therapy or endocrine therapy. Hormone therapy can be used to treat several types of cancer.

Immunotherapy. This type of treatment helps your body's natural defenses fight the cancer. Immunotherapy has developed rapidly during the last few years, and is now an important part of treatment for several types of cancer.

Targeted therapy. These treatments target and disable genes or proteins found in cancer cells that the cancer cells need to grow. Targeted therapy can treat many types of cancer.

How long will I need chemotherapy?

Chemotherapy is often given for a specific time, such as 6 months or a year. Or you might receive chemotherapy for as long as it works.

Side effects from many anti-cancer 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.

Some cancers are treated with less recovery time between cycles. This is called a dose-dense schedule. It can make chemotherapy more effective against some cancers. But it also increases the risk of side effects.

Your health care team will explain how often and for how long you'll receive chemotherapy. Be sure to talk with your doctor, nurse, or other team member regularly about side effects of chemotherapy, including what you can expect and what you are experiencing.

Questions to ask the health care team

  • What type of chemotherapy do you recommend for me? Why?

  • What are the goals of this chemotherapy?

  • Will chemotherapy be my only cancer treatment? If not, will it be given before, during, or after another cancer treatment?

  • How will I receive chemotherapy, such as by pill or by IV? How often? For how long?

  • Where will I receive this chemotherapy?

  • If I need to come into the medical center for chemotherapy, how long will it take to give the treatment? How often will I need to travel to the center?

  • If I should take this medication at home, are there special instructions on how to store or handle the chemotherapy? What should I do if I miss a dose?

  • What are the possible side effects of this treatment in the short term?

  • Will this treatment affect my daily life? Will I be able to work, exercise and do my usual activities?

  • Will chemotherapy affect what or how I eat? If so, how can I eat well during my treatment period?

  • What are the possible long-term effects of this treatment?

  • Who should I talk with about any side effects I experience? How soon?

  • Who should I call with questions or problems?

  • How can I reach them during regular office hours? After hours?

  • If I'm very worried or anxious about having this treatment, what can I talk with?

  • If I'm worried about managing the cost of this treatment, who can help me?

  • How will we know if the chemotherapy is working?

  • Will I need any tests or scans before, during, or after chemotherapy?

  • Could the dose or duration of my chemotherapy change over time?

Related Resources

What to Expect When Having Chemotherapy

Catheters and Ports in Cancer Treatment

Making Decisions About Cancer Treatment

Side Effects of Chemotherapy

Small Changes to Help Food Taste Better When You Have Cancer

More Information

Chemocare.com: What is Chemotherapy?

National Cancer Institute: Chemotherapy to Treat Cancer