Chemotherapy (chemo) usually refers to the use of medicines or drugs to treat cancer. The thought of having chemotherapy frightens many people. But knowing what chemotherapy is, how it works, and what to expect can often help calm your fears. It can also give you a better sense of control over your cancer treatment.
How is Chemotherapy Used to Treat Cancer?
Chemotherapy is the use of any drug to treat any disease. But to most people, the word chemotherapy means drugs used for cancer treatment. It’s often shortened to “chemo.”
Surgery and radiation therapy remove, kill, or damage cancer cells in a certain area, but chemo can work throughout the whole body. This means chemo can kill cancer cells that have spread (metastasized) to parts of the body far away from the original (primary) tumor.
Goals of chemotherapy treatment
If your doctor has recommended chemotherapy to treat your cancer, it’s important to understand the goals of treatment when making treatment decisions. There are three main goals for chemotherapy (chemo) in cancer treatment:
Cure
If possible, chemo is used to cure cancer, meaning that the cancer is destroyed – it goes away and doesn’t come back.
Most doctors don’t use the word “cure” except as a possibility or intention. So, when giving treatment that has a chance of curing a person’s cancer, the doctor may describe it as treatment with curative intent.
There are no guarantees, and though cure may be the goal, it doesn’t always work out that way. It often takes many years to know if a person’s cancer is really cured.
Control
If cure is not possible, the goal may be to control the disease. Chemo is used to shrink tumors and/or stop the cancer from growing and spreading. This can help the person with cancer feel better and live longer.
In many cases, the cancer doesn’t completely go away, but is controlled and managed as a chronic disease, much like heart disease or diabetes. In other cases, the cancer may even seem to have gone away for a while, but it’s expected to come back. Then chemo can be given again.
Palliation
Chemo can also be used to ease symptoms caused by the cancer. This is called palliative chemotherapy or palliation.
When the cancer is at an advanced stage, meaning it’s not under control and has spread from where it started to other parts of the body, the goal may be to improve the quality of life or help the person feel better. For instance, chemo may be used to help shrink a tumor that’s causing pain or pressure.
Planning chemotherapy treatments
You and your cancer doctor, called an oncologist, will decide what drug or combination of drugs you will get. Your doctor will choose the doses, how the drugs will be given, and how often and how long you’ll get treatment. All of these decisions will depend on the type of cancer, where it is, how big it is, and how it affects your normal body functions and overall health.
Cancer can be treated with a single chemo drug, but often several drugs are used in a certain order or in certain combinations (called combination chemotherapy). Different drugs that work in different ways can work together to kill more cancer cells. This can also help lower the chance that the cancer may become resistant to any one chemo drug.
Sometimes chemo is the only treatment you need. More often, chemo is used with surgery or radiation therapy or both. Here’s why:
Determining which chemotherapy drugs to use
In some cases, the best choice of doses and schedules for each chemo drug is clear, and most doctors would recommend the same treatment. In other cases, less may be known about the single best way to treat people with certain types and stages of cancer. In these cases, different doctors might choose different drug combinations with different schedules.
Factors to consider when choosing which drugs to use include:
Doctors take these factors into account, along with information published in medical journals and textbooks describing the outcomes of similar patients treated with chemo.
Determining chemotherapy doses
Most chemotherapy (chemo) drugs are strong medicines that have a fairly narrow range for dose safety and effectiveness. Taking too little of a drug will not treat the cancer well and taking too much may cause life-threatening side effects. For this reason, doctors must calculate chemo doses very precisely.
Depending on the drug(s) to be given, there are different ways to determine chemo doses. Most chemo drugs are measured in milligrams (mg).
The overall dose may be based on a person’s body weight in kilograms (1 kilogram is 2.2 pounds). For instance, if the standard dose of a drug is 10 milligrams per kilogram (10 mg/kg), a person weighing 110 pounds (50 kilograms) would get 500 mg (10 mg/kg x 50 kg).
Some chemo doses are determined based on body surface area (BSA), which are calculated using height and weight. BSA is expressed in meters squared (m2).
Because children’s bodies process drugs differently, dosages for children and adults differ, even after BSA is taken into account. Children may have different levels of sensitivity to the drugs, too. For the same reasons, dosages of some drugs may also be adjusted for people who:
Determining a chemotherapy schedule (cycle)
Chemotherapy is commonly given at regular intervals called cycles. A cycle may be a dose of one or more drugs followed by several days or weeks without treatment. This gives normal cells time to recover from drug side effects. Sometimes, doses may be given a certain number of days in a row, or every other day for several days, followed by a period of rest. Some drugs work best when given continuously over a set number of days.
Each drug is given on a schedule that makes the most of its anti-cancer actions and minimizes side effects. If more than one drug is used, the treatment plan will say how often and exactly when each drug should be given. The number of cycles given may be decided before treatment starts, based on the type and stage of cancer. In some cases, the number is flexible, and will take into account how the treatment affects the cancer and the person’s overall health.
Changing chemotherapy doses and schedules
In most cases, the most effective doses and schedules of drugs to treat specific cancers have been found by testing them in clinical trials. It’s important, when possible, to get the full course of chemo, the full dose, and keep the cycles on schedule. This gives a person the best chance of getting the maximum benefit from treatment.
There may be times, though, when serious side effects require adjusting the chemo plan (dose and/or schedule) to allow you time to recover. Sometimes, you might be given supportive medicines to help your body recover more quickly. Again, the key is to give enough chemo to kill the cancer cells without causing other serious problems.
How Chemotherapy Drugs Work
More than 100 chemotherapy or chemo drugs are used to treat cancer – either alone or in combination with other drugs or treatments. These drugs are very different in their chemical composition, how they are taken, their usefulness in treating specific forms of cancer, and their side effects.
Chemotherapy works with the cell cycle
Chemotherapy drugs target cells at different phases of the process of forming new cells, called the cell cycle. Understanding how these drugs work helps doctors predict which drugs are likely to work well together. Doctors can also plan how often doses of each drug should be given based on the timing of the cell phases.
Cancer cells tend to form new cells more quickly than normal cells and this makes them a better target for chemotherapy drugs. However, chemo drugs can’t tell the difference between healthy cells and cancer cells. This means normal cells are damaged along with the cancer cells, and this causes side effects. Each time chemo is given, it means trying to find a balance between killing the cancer cells (in order to cure or control the disease) and sparing the normal cells (to lessen side effects).
Types of chemo drugs
Chemo drugs can be grouped by how they work, their chemical structure, and their relationships to other drugs. Some drugs work in more than one way, and may belong to more than one group. (Note: not all chemotherapy drugs are listed here.)
Knowing how the drug works is important in predicting side effects from it. This helps doctors decide which drugs are likely to work well together. If more than one drug will be used, this information also helps them plan exactly when each of the drugs should be given (in which order and how often).
Alkylating agents
Alkylating agents keep the cell from reproducing by damaging its DNA. These drugs work in all phases of the cell cycle and are used to treat many different cancers, including cancers of the lung, breast, and ovary as well as leukemia, lymphoma, Hodgkin disease, multiple myeloma, and sarcoma, .
Because these drugs damage DNA, they can affect the cells of the bone marrow which make new blood cells. In rare cases, this can lead to leukemia. The risk of leukemia from alkylating agents is “dose-dependent,” meaning that the risk is small with lower doses, but goes up as the total amount of the drug used gets higher. The risk of leukemia after getting alkylating agents is highest about 5 to 10 years after treatment.
Examples of alkylating agents include:
Antimetabolites
Antimetabolites interfere with DNA and RNA growth by substituting for the normal building blocks of RNA and DNA. These agents damage cells during the phase when the cell’s chromosomes are being copied. They are commonly used to treat leukemias, cancers of the breast, ovary, and the intestinal tract, as well as other types of cancer.
Examples of antimetabolites include:
Anti-tumor antibiotics
These drugs are not like the antibiotics used to treat infections. They work by changing the DNA inside cancer cells to keep them from growing and multiplying.
Anthracyclines: Anthracyclines are anti-tumor antibiotics that interfere with enzymes involved in copying DNA during the cell cycle. (Enzymes are proteins that start, help, or speed up the rate of chemical reactions in cells.) They are widely used for a variety of cancers.
Examples of anthracyclines include:
A major concern when giving these drugs is that they can permanently damage the heart if given in high doses. For this reason, lifetime dose limits are often placed on these drugs.
Anti-tumor antibiotics that are not anthracyclines include:
Topoisomerase inhibitors
These drugs interfere with enzymes called topoisomerases, which help separate the strands of DNA so they can be copied. (Enzymes are proteins that cause chemical reactions in living cells.) Topoisomerase inhibitors are used to treat certain leukemias, as well as lung, ovarian, gastrointestinal, and other cancers.
Topoisomerase inhibitors are grouped according to which type of enzyme they affect:
Topoisomerase I inhibitors include:
Topoisomerase II inhibitors include:
Topoisomerase II inhibitors can increase the risk of a second cancer – acute myelogenous leukemia (AML) – as early as 2 to 3 years after the drug is given.
Mitotic inhibitors
Mitotic inhibitors are compounds derived from natural products, such as plants. They work by stopping cells from dividing to form new cells but can damage cells in all phases by keeping enzymes from making proteins needed for cell reproduction.
Examples of mitotic inhibitors include:
They are used to treat many different types of cancer including breast, lung, myelomas, lymphomas, and leukemias. These drugs may cause nerve damage, which can limit the amount that can be given.
Corticosteroids
Corticosteroids, often simply called steroids, are natural hormones and hormone-like drugs that are useful in the treatment of many types of cancer, as well as other illnesses. When these drugs are used as part of cancer treatment, they are considered chemotherapy drugs.
Examples of corticosteroids include:
Steroids are also commonly used to help prevent nausea and vomiting caused by chemo. They are used before chemo to help prevent severe allergic reactions, too.
Other chemotherapy drugs
Some chemotherapy drugs act in slightly different ways and do not fit well into any of the other categories.
Examples include drugs like L-asparaginase, which is an enzyme, and the proteosome inhibitor bortezomib (Velcade®).
Other types of drugs used to treat cancer
Other drugs and biological treatments are used to treat cancer, but aren’t considered chemotherapy. They often have less side effects than chemotherapy.. Many are used along with chemo.
Targeted therapies
Targeted therapies attack cancer cells more specifically than traditional chemotherapy drugs. These drugs can be used as part of the main treatment, or they may be used after treatment to keep the cancer under control or keep it from coming back.
Differentiating agents
These drugs act on the cancer cells to make them mature into normal cells. Examples include the retinoids, tretinoin (ATRA or Atralin®) and bexarotene (Targretin®), as well as arsenic trioxide (Arsenox®).
Hormone therapy
Drugs in this category are sex hormones, or hormone-like drugs, that are used to slow the growth of breast, prostate, and endometrial (uterine) cancers, which normally grow in response to natural sex hormones in the body. They work by making the cancer cells unable to use the hormone they need to grow, or by preventing the body from making the hormone.
Immunotherapy
Some treatments are given to people with cancer to help their immune systems recognize and attack cancer cells.
Questions to Ask About Chemotherapy
Before choosing chemo as a treatment option, you should understand the expected benefits, side effects, and risks. You will also have to give your written permission to get chemo. (This is called informed consent.)
Consider asking your doctor or nurse these questions before signing the consent form. It may help to write down questions to take with you to your next visit. Learn as much as you can about your treatment, and get an idea of the expected outcome.
Here are some tips to help you remember your doctor’s answers:
You might want to look at After Diagnosis: A Guide for Patients and Families for more ideas about the things you and your family may want to know.
Getting Chemotherapy
Learn the basics about getting chemotherapy and important safety precautions you need to consider to protect your health and those you live with.
Where will I get chemotherapy?
The place you get your treatment depends on which chemotherapy (chemo) drugs you’re getting, the drug doses, your hospital’s policies, your insurance coverage, what you prefer, and what your doctor recommends.
You may get chemotherapy:
Some of these settings may have private treatment rooms, while others treat many patients together in one large room. Ask your doctor or nurse about this ahead of time so you know what to expect your first day.
How often will I need chemotherapy and how long will it last?
How often you get chemo and how long your treatment lasts depend on the kind of cancer you have, the goals of the treatment, the drugs being used, and how your body responds to them.
You may get treatments daily, weekly, or monthly, but they’re usually given in on-and-off cycles. This means, for example, that you may get chemo the first 2 weeks and then have a week off, making it a cycle that will start over every 3 weeks. The time off lets your body build healthy new cells and regain its strength.
Your cancer care team can tell you how many cycles are planned and how long they expect your treatment to last.
Many people wonder how long the actual drugs stay in their body and how they’re removed. Your kidneys and liver break down most chemo drugs which then leave your body through urine or stool. How long it takes your body to get rid of the drugs depends on many things, including the type of chemo you get, other medicines you take, your age, and how well your kidneys and liver work. Your cancer care team will tell you if you need to take any special precautions because of the drugs you are getting.
If your cancer comes back, you might have chemo again. This time, you could be given different drugs to relieve symptoms or to slow the cancer’s growth or spread. Side effects might be different, depending on the drugs, the doses, and how they’re given.
How will I be given chemotherapy ?
Through a vein
Most chemotherapy drugs are put right into your bloodstream through a tiny, soft, plastic tube called a catheter. A needle is used to put the catheter into a vein in your forearm or hand; then the needle is taken out, leaving the catheter behind. This is called intravenous or IV treatment. Intravenous drugs are given in these ways:
The needles and catheters can scar and damage veins with ongoing chemo. Another option is the central venous catheter (CVC). The CVC is a bigger catheter that’s put into a large vein in the chest or arm. It stays in as long as you’re getting treatment so you won’t need to be stuck with a needle each time. Different kinds of CVCs are available.
Many people talk about CVC options with their doctor even before starting treatment. Some find out during treatment that they need a CVC because their hand and arm veins aren’t going to last to complete the planned chemo. Your doctor can help you decide if you need a CVC and the right type of CVC for you.
By mouth
You swallow the chemo as a pill, capsule, or liquid – just like other medicines. This chemo can often be taken at home. If you take chemo drugs by mouth, it’s very important to take the exact dosage, at the right time, for as long as you’re supposed to do so. For more, please see Oral Chemotherapy: What You Need to Know.
Intrathecal or IT
IT chemo is put into the spinal canal and goes into the fluid that surrounds the brain and spinal cord to reach cancer cells there. This fluid is called the cerebrospinal fluid or CSF. This is important because most chemo drugs delivered by IV or by mouth are unable to reach the brain due to the blood-brain barrier.
Chemo can be delivered to the CSF through a needle placed in the spinal area, or a long-term catheter and port that can be put under the skin on your head during surgery. This port is called an Ommaya reservoir. The Ommaya is a small drum-like device with a small tube attached to it. The tube goes into the CSF in a cavity of your brain. The Ommaya stays in place under your scalp until treatment is done.
Intra-arterial
In this use, the chemo drug is put right into the main artery that supplies blood to the tumor to treat a single area (such as the liver, an arm, or leg). This method helps limit the effect the drug has on other parts of the body and is called regional chemo.
Intracavitary
Chemo drugs may be given through a catheter into an enclosed area of the body such as the abdomen (this is called intraperitoneal chemo) or chest (called intrapleural chemo).
Intramuscular or IM
The drug is put in through a needle into a muscle (as an injection or shot).
Intralesional
A needle is used to put the drug right into a tumor. It’s only possible when the tumor can be safely reached with a needle.
Intravesical
The chemo is put right into the bladder through a soft catheter. It stays in for a few hours and is then drained out, and the catheter is removed.
Topical
The drug is put right on an area of cancer on the skin as a cream, gel, or ointment.
What should I eat before my first chemo treatment?
Your chemo can take anywhere from a few minutes to many hours. Make sure you eat something before treatment. Most people find that a light meal or snack an hour or so before chemo works best. If you’ll be there several hours, plan ahead and bring a small meal or snacks in an insulated bag or cooler. Find out if there’s a refrigerator or microwave you can use.
Can I be around my family and friends while I’m getting chemo?
Most chemo drugs make you less able to fight infection, but there are ways you can avoid them.
How can I protect myself and those I live with while I’m getting chemo?
There are many things you can do during and after chemo to keep yourself and your loved ones from being affected by the chemo drugs while your body is getting rid of them. It takes about 48 hours for your body to break down and/or get rid of most chemo drugs.
Most of the waste comes out in your body fluids – urine, stool, tears, and vomit. The drugs are also in your blood. When chemo drugs get outside your body, they can harm or irritate skin – yours or even other people’s. Keep in mind that this means toilets can be a hazard for children and pets, and it’s important to be careful. Talk to your cancer care team about these and any other precautions you should follow.
During – and for 48 hours after – chemo:
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