You are here: Home Managing Your ... Chemotherapy 101: ... Basic Information ... Summary
Information about all aspects of finances affected by a serious health condition. Includes income sources such as work, investments, and private and government disability programs, and expenses such as medical bills, and how to deal with financial problems.
Information about all aspects of health care from choosing a doctor and treatment, staying safe in a hospital, to end of life care. Includes how to obtain, choose and maximize health insurance policies.
Answers to your practical questions such as how to travel safely despite your health condition, how to avoid getting infected by a pet, and what to say or not say to an insurance company.


Chemotherapy (often referred to as "Chemo") is the use of drugs to treat disease. 

Chemotherapy has one of three goals: cure, remission, or palliation (relief of pain).  

The use of drugs to treat cancer started after World War II when it was realized that Mustard Gas affected cancer cells.

Chemotherapy is aimed at rapidly reproducing cells. Different drugs work on different cyles of cell reproduction.

A single drug can be used to treat cancer. However, for the most part, a combination of drugs with different actions can work together to kill more cancer cells. (The use of more than one drug in chemotherapy is called combination chemotherapy.)  A combination can also reduce the chance that the cancer may become resistant to any one chemo drug. More than 100 chemo drugs are used in many combinations.

Chemo is sometimes used alone. More often it is used in combination with other treatments such as surgery or radiation. When used with other treatments, chemotherapy is known as neoadjuvant therapy (before surgery or radiation), or as adjuvant therapy (after surgery or radiation).

Chemotherapy is also known as: Chemo, Antineoplastic (meaning anti-cancer) therapy, and Cytotoxic (cell-killing) therapy.

How Does Chemotherapy Work?

To understand how chemotherapy works as a treatment on a more technical level, it is helpful to understand the normal life cycle of a cell in the body. All living tissue is composed of cells. Cells grow and reproduce to replace cells lost during injury or normal "wear and tear." The cell cycle is a series of steps that both normal cells and cancer cells go through in order to form new cells.

There are 5 phases in the cell cycle, which are labeled below using letters and numbers. Since cell reproduction happens over and over, the cell cycle is shown below as a circle. All the steps lead back to the resting phase (G0), which is the starting point.

After a cell reproduces, the 2 new cells are identical. Each of the 2 cells that is made from the first cell can go through this cell cycle again when new cells are needed.

The Cell Cycle
The Cell Cycle

  • G0 phase (resting stage): The cell has not yet started to divide. Cells spend much of their lives in this phase. Depending on the type of cell, G0 can last for a few hours to a few years. When the cell is signaled to reproduce, it moves into the G1 phase.
  • G1 phase: During this phase, the cell starts making more proteins and growing larger, so the new cells will be of normal size. This phase lasts about 18 to 30 hours.
  • S phase: In the S phase, the chromosomes containing the genetic code (DNA) are copied so that both of the new cells formed will have matching strands of DNA. This phase lasts about 18 to 20 hours.
  • G2 phase: In the G2 phase, the cell checks the DNA and prepares to start splitting into 2 cells. It lasts from 2 to 10 hours.
  • M phase (mitosis): In this phase, which lasts only 30 to 60 minutes, the cell actually splits into 2 new cells.

  • This cell cycle is important to cancer doctors (oncologists) because many chemotherapy drugs work only on cells that are actively reproducing (not on cells in the resting phase, G0). Some drugs specifically attack cells in a particular phase of the cell cycle (the M or S phases, for example). Understanding how these drugs work helps oncologists 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.

When chemotherapy drugs attack reproducing cells, they cannot tell the difference between reproducing cells of normal tissues (that are replacing worn-out normal cells) and cancer cells. The damage to normal cells can cause side effects. Each time chemotherapy is given, it involves trying to find a balance between destroying the cancer cells (in order to cure or control the disease) and sparing the normal cells (to lessen unwanted side effects).

History Of Chemotherapy

The word chemotherapy was once used to mean any medicine used to treat any disease. Even taking an aspirin was described as chemotherapy. Today, chemotherapy, or "chemo" for short, most often means taking certain types of medicines (drugs) to treat cancer.

The first drug used for cancer chemotherapy did not start out as a medicine. Mustard gas was used as a chemical warfare agent during World War I and was studied further during World War II. During a military operation in World War II, a group of people were accidentally exposed to mustard gas and were later found to have very low white blood cell counts. Doctors reasoned that an agent that damaged the rapidly growing white blood cells might have a similar effect on cancer. Therefore, in the 1940s, several patients with advanced lymphomas (cancers of certain white blood cells) were given the drug by vein, rather than by breathing the irritating gas. Their improvement, although temporary, was remarkable. That experience led researchers to look for other substances that might have similar effects against cancer. As a result, many other drugs have been developed.

The Goals of Treatment With Chemotherapy

There are 3 possible goals for chemotherapy treatment: cure, control and palliation.


If possible, chemotherapy is used to cure the cancer, meaning that the tumor or cancer disappears and does not return. However, most doctors do not use the word "cure" except as a possibility or intention. When giving treatment that has a chance of curing a person's cancer, the doctor may describe it as treatment with curative intent. But it can take many years to know whether a person's cancer is actually cured.

Many oncologists suggest that rather than "cure," it is better to think of cancer as a chronic condition which occasionally has acute phases. This kind of           thinking brings front and center the part you can play on an ongoing basis by eating right, exercising, doing what you can to reduce stress and getting               appropriate rest/sleep.


If cure is not possible, the goal may be to control the disease - to shrink any tumors and to stop the cancer from growing and spreading. This can help someone with cancer feel better and hopefully live longer. In many cases, the cancer does not completely go away, but is controlled and managed as a chronic disease, much like hypertension or diabetes. In other cases, the cancer may even seem to have gone away for a while, but it is expected to come back.


When the cancer is at an advanced stage, chemotherapy drugs may be used to relieve symptoms caused by the cancer. When the only goal of treatment is to improve the quality of life, it is called palliation.

How Chemotherapy Treatments Are Given

Chemotherapy Form

Chemotherapy comes in two forms:

  • a pill 
  • a liquid that enters the body through a needle in a vein (intraveneously). (Those clear plastic bags of liquid that hang on a pole that we see on every t.v. show that takes place in a hospital).

Chemotherapy injections are given in a private foctor's office, in a hospital, or in a cancer center.

Intraveneous chemotherapy is given in cycles. For example, a dose may be given  5 days a week for a few weeks, then a few weeks without, then more weeks with chemo. Or it may be given once a week for a number of weeks, etc. The time off gives your body a chance to recover between treatments. A full course of chemo could be a few months, or 12 months, or longer or shorter depending on the spefic situation.

While pills may be more convenient because they can be taken anywhere, they may not be treated the same by your health insurance company as chemotherapy given intraveneously. Chemo given intraveneously is covered like a treatment. Chemo given in pill form may be treated like a drug which means you pay a larger share of the cost. 

Chemotherapy: How Intraveneous Chemotherapy Is Given

Chemotherapy is given in a health facility such as a hospital or outpatient facility.

Before giving the dose, a nurse will draw your blood to check whether the treatment to date has affected the blood-producing cells in your bone marrow or the function of your liver. If the results are okay, the nurse will start the intraveneous line (IV) through which the drug will be injected.

If the blood results are not okay, your oncologist may lower the dose or postpone the treatment.


Will Chemotherapy Be My Only Treatment For Cancer?

Sometimes chemo is the only treatment you will need. More often, chemo is used along with surgery or radiation therapy or with both. Here's why:
  • Chemo may be used to shrink a tumor before surgery or radiation therapy.
  • It may be used after surgery or radiation therapy to help kill any remaining cancer cells.
  • It may be used with other treatments if your cancer returns.

When chemo is given after surgery to kill any cancer cells that may still be present, it is called adjuvant therapy. When chemo is used to shrink a tumor before surgery or radiation therapy, it is called neoadjuvant therapy.

How Chemotherapy Is Different From Other Cancer Treatments

It differs from surgery or radiation in that it is almost always used as a systemic treatment. This means the medicines travel throughout the body to reach cancer cells wherever they may have spread.

Treatments like radiation and surgery act in a specific area such as the breast, lung, or colon, and so are considered local treatments.

How Often Chemotherapy Is Given And For How Long

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 are usually given in on-and-off cycles. These breaks allow rest periods so that your body can build healthy new cells and regain its strength.

Many people wonder how long the actual drugs stay in their body and how they are removed. Most chemo drugs are broken down by your kidneys and liver and then removed from your body through your urine or stool. The time 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 your kidney and liver functions. Your doctor will tell you if you will need to take any special precautions because of the drugs you are getting.

If your cancer returns, chemo may be used again. This time you may be given different drugs to relieve symptoms or to slow the cancer's growth or spread. Side effects may be different, depending on the drug, the dose, and how it is given.