Revised March 2007
This page provides general information on drug therapy and what it can do. For information on specific cancer drugs, see our Cancer Drug Manual.
Overview
Cancer drugs such as chemotherapy, hormone therapy, and other biological or genetic treatments, are used to destroy cancer cells. Sometimes the goal of cancer drugs is to cure. When cure is not possible, cancer drugs can often prolong life or improve quality of life.
Drugs can work in a number of ways to kill cancer cells. Chemotherapy drugs (cytotoxic) can slow down cancer cells from growing or multiplying. They can also encourage these cells to die naturally (apoptosis). In general, chemotherapy drugs can harm some of the healthy cells in the same way, causing side effects.
Hormone drugs usually stop your body’s hormones from helping some cancers to continue to grow. Biological therapy involves drugs which help the immune system in your body to fight against cancer. Targeted drug therapy includes drugs which are designed to attack only certain areas found mainly in cancer cells. These drugs tend to cause less harm to healthy cells, which means fewer side effects.
Chemotherapy uses drugs to treat cancers of the blood and bone marrow as well as for cancers of the lymphatic system (lymphomas). Chemotherapy is also used to treat cancer when it has spread, when it has come back, or when there is a strong chance it could come back (recur). Hormone therapy uses drugs to interfere with hormone production or hormone action, to kill cancer cells or slow their growth. Surgery is also used to remove hormone-producing glands to slow or kill cancer cells.
Cancer drugs can:
- Cure specific types of cancer
- Shrink tumours prior to surgery or radiation therapy
- Prevent cancers from spreading
- Control the spread of cancer when a tumour cannot be completely removed by surgery or radiation therapy
- Relieve symptoms such as pain
- Stop or slow tumour growth
If you would like assistance dealing with side effects from cancer drugs please go to our Coping with Cancer -> Managing Symptoms and Side Effects section of the website.
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Why do some patients receive cancer drugs and others don't?
Chemotherapy is recommended to patients as an option based on the following:
- Does the specific cancer react to chemotherapy? Only certain types of cancers (the ones with large proportions of dividing cells) are responsive to drugs. These are usually small tumours (either because they are detected early or because most of the tumour has been removed by surgery or radiation) or are systemic cancers like leukemias and lymphomas (systemic means they are everywhere in the body)
- Location of the Tumour: Even if the tumour can respond to cancer drugs, its actual location will affect the choice of treatment. In some cases, tumour location will make cancer drugs, perhaps combined with radiation therapy, the only treatment option. For example, certain brain tumours cannot be removed surgically, so cancer drugs and/or radiation therapy are the only choices
- General Condition of the Patient: Your body has to be otherwise healthy in order to tolerate some chemotherapy drugs. Cancer patients are often shocked when they hear medical personnel refer to them as healthy. How can someone with cancer be healthy? When doctors term a cancer patient "healthy", they are referring to how well the body is functioning, except for the site of the cancer. When they speak about a cancer patient being "sick" they are talking about a serious breakdown in the functioning of vital organs and systems
Selecting Specific Drugs
For some cancers, only one drug is needed for effective chemotherapy. For others, a combination of drugs is used.
The selection of drug combinations depends on three things:
- The proven effectiveness of each drug when used alone against that cancer
- A difference in each drug's method of attacking the cancer (so that maximum cancer-kill can be achieved in each cycle while minimizing the chance of developing resistance to any one drug)
- A difference in the side effects of each drug (minimally overlapping toxicity), so that your healthy tissue will not be badly damaged by the cancer drugs
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How are cancer drugs given?
How often you receive drugs depends on your:
- Treatment program (which may be called a regime, regimen, or protocol)
- Cycle length: how long your cycle is (from the start of one round of chemotherapy to the start of another)
- Number of cycles: how many cycles are in your treatment plan. Typical cycles are two to six weeks long. The cycle is divided into two parts: the period when you receive the drugs and the period of rest and recovery before the next cycle
Intravenous
Intravenous (IV) drugs are injected directly into a vein. This is done either in the form of a fluid drip (commonly called an "IV" or "drip") or as an IV push. If it's given as a drip, a needle is inserted into your vein. The needle is connected to a tube that's attached to a bag or bottle of the drug that is hanging on a pole. The drug drips into the vein at a specified rate. An "IV push" is like a regular shot (the drug is in a syringe rather than a bag), but goes directly into a vein.
IV chemotherapy can take from 15 minutes to 12 hours or longer.
If a vein is not easily accessible, a temporary port can be surgically implanted under the skin in the chest or in an arm or leg. The port allows direct access to a vein for the duration of your chemotherapy treatments. The port can remain in place for several years. One or more small scars will result from the placement of this port.
Other Injections
- Intramuscular (IM) - a regular shot into the muscle of the arm, thigh, or buttocks
- Subcutaneous (SQ) - a shot under the skin
- Intra-Arterial (IA) - the same as an IV (drip or push) except that the needle is inserted into an artery instead of a vein
- Intrathecal (IT) - injecting the drug directly into the spinal fluid that circulates over the brain and spinal cord. Sometimes a device is implanted under the skin on top of the head to make access easier
- Intracavitary (IC) 0 injecting drugs directly into a cavity, or "empty space," usually around the lung (pleural space) or into the abdomen
- Regional Perfusion - a technique that concentrates certain drugs in one area (usually arms or legs) by creating a closed-circuit system in the bloodstream. A tourniquet is used to stop the blood flow out of the affected area so that no harm comes to other organs. The drug is put into the artery, which carries it to the cancerous area; it is then taken out of a vein and pumped back into the artery for a continuous high concentration of the drug.
Oral
You swallow the drugs either in the form of pills, capsules or liquid.
Topical
For some cancers, usually skin cancers, drugs can be administered in the form of a cream.
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Side Effects
If you would like assistance dealing with side effects from cancer drugs please go to the Coping with Cancer -> Managing Symptoms and Side Effects section of the website.