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Cancer happens when cells in the body become abnormal and begin to grow and divide out of control. Cancerous cells can invade surrounding tissues and also spread to distant parts of the body through a process called metastasis.

An estimated 19.3 million new cancer diagnoses and almost 10 million cancer deaths occurred worldwide in 2020. In 2019, cancer was the second leading cause of death in the United States, behind heart disease.

Chemotherapy is a type of cancer treatment that uses drugs to kill cancer cells. These types of drugs are called chemotherapeutic agents. They work by slowing or stopping the growth of cancer cells.

Below, we’ll cover the types of chemotherapeutic agents, how they work, their side effects, and more.

There are several types of chemotherapeutic agents. Chemotherapeutic agents are typically classified based on factors like chemical structure and how they work to treat cancer.

The cell cycle is the process that cells in the body use to grow and divide. Chemotherapeutic agents work by targeting phases in the cell cycle.

Since cancer cells grow and divide more rapidly than healthy cells, they’re a good target for these drugs.

Examples of the different categories of chemotherapeutic drugs are:

  • Alkylating agents. Alkylating agents work by damaging a cell’s DNA and can be used to treat a variety of cancers. Some examples of alkylating agents are cisplatin and melphalan.
  • Antimetabolites. DNA is made up of building blocks called nucleotides. Antimetabolites work by substituting in for normal nucleotides, interfering with DNA replication. Examples of antimetabolites are 5-fluorouracil and gemcitabine.
  • Antitumor antibiotics. Antitumor antibiotics are derived from compounds made by bacteria. They work by binding to DNA so that it cannot make copies of itself. Two types of antitumor antibiotic are doxorubicin and bleomycin.
  • Plant alkaloids. Plant alkaloids are compounds derived from plants. They work by stopping cells from splitting into new cells and include drugs like cabazitaxel and topotecan.

There are other chemotherapeutic agents that don’t fit well into any of the categories above.

There are a few different goals of treatment with chemotherapeutic agents, which is called chemotherapy:

  • Curative. The goal of curative chemotherapy is to rid the body of detectable cancer cells, achieving a state of remission.
  • Control. It’s possible that cancer may not be able to be completely eliminated from the body. In this case, chemotherapy can be used to help control the cancer and prevent it from growing or spreading.
  • Adjuvant. Sometimes surgery is used to remove a tumor. In this situation, adjuvant chemotherapy may be used after your procedure to help eliminate any cancerous cells that still remain in the body.
  • Neoadjuvant. Neoadjuvant chemotherapy may be utilized when a tumor is too big to be operated on. The goal is to use chemotherapeutic agents to reduce the size of the tumor to allow for surgery.
  • Palliative. Palliative chemotherapy is used when it’s no longer possible to remove all the cancer cells in your body, such as when cancer has metastasized. Instead, the goal is to reduce symptoms and improve quality of life.

It’s possible that you may receive one chemotherapeutic agent as a part of your cancer treatment. However, a combination of chemotherapeutic agents is often used.

This is because different categories of chemotherapeutic agents have different ways of acting on cancer cells. Additionally, the use of multiple chemotherapeutic agents reduces the risk of cancer becoming resistant, which can happen when a single drug is used.

It’s also possible that chemotherapeutic agents may be given along with other types of cancer treatments. Some examples include radiation therapy and targeted therapy.

Your doctor will select one or more chemotherapeutic agents based on several factors. These include:

  • the specific type of cancer that you have
  • the stage of your cancer
  • whether cancer cells have specific biomarkers
  • if any other types of cancer treatment have been used previously
  • your age
  • your overall health, which takes into account other medical conditions and medications

The dose of a chemotherapeutic agent must be carefully considered. This helps to optimize effectiveness while reducing the risk of serious side effects.

Dosage is determined based on either your body weight or body surface area, which takes both height and weight into account. Additionally, the dose of a chemotherapeutic agent may be modified because of factors like:

  • age
  • other existing health conditions
  • medications you’re taking
  • additional cancer treatments you’re receiving
  • how well you’re tolerating chemotherapy
  • how the cancer is responding to chemotherapy

You can receive chemotherapy in several forms. It’s most commonly given intravenously (via IV). However, depending on your individual situation, it may be given in other ways as well, such as:

  • taking it as a pill or tablet (oral)
  • injecting it:
    • into your body cavity (intraperitoneal)
    • into an artery that’s feeding the cancer (intra-arterial)
  • applying it directly to the skin (topical)

Chemotherapy cycles

Chemotherapeutic agents are typically given in cycles. This means that you’ll receive your treatment for one or more days before having several days or weeks of rest. There are typically four to eight cycles in a course of chemotherapy treatment.

Administering chemotherapeutic agents in cycles has a few purposes:

  • Chemotherapeutic agents target cells that are growing and dividing. Because not all cancer cells are dividing at the same time, they won’t all be killed after a single cycle. However, subsequent cycles can work to kill these cells.
  • Receiving chemotherapy can be hard on your body. Allowing for some time to rest can help you to recover from your treatment.

How long can a treatment session take?

The length of a chemotherapy treatment session can vary. In some situations, it may take about half an hour, while in others it may last several hours. Be sure to ask your care team about what to expect so that you can prepare accordingly.

There are also systems where you may receive chemotherapeutic agents continuously over a set period of time. This is given by an infusion pump that you wear.

You can receive chemotherapy as either an inpatient or an outpatient. This will depend on your specific situation.

Inpatient means that you’ll stay overnight in the hospital. Your doctor may recommend this if you’re having a very intensive treatment or if the chemotherapeutic agent in use requires careful monitoring.

Outpatient means you go home after treatment. If you’re having outpatient treatment, you may visit a treatment center or clinic to receive it. If you’re taking chemotherapeutic agents as pills or tablets, you may also be able to administer them yourself at home.

A limitation of chemotherapeutic agents is that they don’t differentiate between cancer cells and healthy cells. Because of this, healthy cells can be damaged during treatment with chemotherapeutic agents.

As such, chemotherapeutic agents can cause a variety of side effects, such as:

How long side effects may last depends on factors like your overall health and the type of chemotherapeutic agent. Most side effects fade after chemotherapy ends, although some may be long lasting.

There are many ways to help manage the side effects of chemotherapeutic agents. It’s important to talk with members of your care team about what types of side effects to expect and what you can do to help prevent or ease them.

Some general tips to help manage side effects from your chemotherapy treatment include:

  • Try to eat a balanced diet during your treatment. Chemotherapy can be hard on your body, so you’ll also need plenty of calories and protein to help it recover.
  • If you’re having digestive side effects, consider eating several small meals throughout the day instead of three large ones.
  • Talk with your care team about the types of foods to focus on if you’re having symptoms like nausea, diarrhea, or constipation.
  • Drink plenty of water or clear liquids each day in order to stay hydrated.
  • Aim for at least 8 hours of sleep each night. It may also help to take short naps throughout the day.
  • Try to stay active to the best of your ability, as this can help fatigue, promote better sleep, and lift mood. Some activities to consider are going for a walk or doing yoga.
  • Don’t be afraid to rest when you need it and limit what you do to the most important activities. If you need extra help getting things done, don’t hesitate to reach out to loved ones.

No, chemotherapeutic agents aren’t the only types of cancer treatment. Some other treatments that may be recommended include:

  • Surgery. During surgery for cancer, a surgeon will work to remove cancer cells from your body. This is typically a treatment option for individuals with a solid tumor that’s localized to one area of the body.
  • Radiation therapy. Radiation therapy uses strong radiation to kill cancer cells and can be given either externally or internally. It’s often used as a neoadjuvant or adjuvant therapy and can also be used to ease cancer symptoms.
  • Targeted therapy. Targeted therapy uses drugs that target specific markers on cancer cells. An example of targeted therapy are drugs that target the HER2 protein on the surface of breast cancer cells.
  • Hormone therapy. Some cancers, such as breast cancer and prostate cancer, utilize hormones in your body to grow and thrive. Hormone therapy works by preventing hormones from interacting with cancer cells.
  • Immunotherapy. Immunotherapy helps your immune system respond to cancer, although it’s not yet as widely used as other cancer treatments. Examples of immunotherapy include monoclonal antibodies and CAR T-cell therapy.
  • Stem cell transplant. In a stem cell transplant, a high dose of chemotherapy is used to kill the cells in your bone marrow. Healthy stem cells previously harvested from you or a donor are transplanted to reestablish the bone marrow. It’s often used for cancers such as:

It’s not uncommon to receive a combination of different treatment types. If you have a recent cancer diagnosis, your care team will work to develop a treatment plan that’s appropriate for your situation.

You can receive chemotherapy at a variety of different locations. These include:

  • hospitals, either in an inpatient or an outpatient unit
  • chemotherapy clinics
  • a doctor’s office
  • at home

The National Cancer Institute (NCI) recognizes cancer centers throughout the United States for excellence in cancer care and research. You can find an NCI-designated cancer center close to you on their “Find a Cancer Center” page.

Other resources for finding chemotherapy and cancer care near you include:

Clinical trials

Another option to consider is enrolling in a clinical trial. Many clinical trials test new approaches to cancer treatment. There are clinical trials running for all types and stages of cancer. Find an NCI-supported clinical trial here.

Chemotherapy is a type of cancer treatment that uses drugs called chemotherapeutic agents to stop cancer cells from growing and dividing. There are several categories of chemotherapeutic agents.

Because they target any cell that’s growing and dividing, chemotherapeutic agents can also damage healthy cells. This can lead to side effects like nausea or vomiting, mouth sores, and hair loss.

Chemotherapeutic agents are often used with other cancer treatments. It’s also possible that your cancer treatment may not involve chemotherapeutic agents at all. After a cancer diagnosis, your care team will work with you to develop a treatment plan that’s appropriate for you.