Chemotherapy works by attacking cells at different stages in their reproduction cycle. Cancer cells are rapidly dividing cells, so certain drugs can target them. But unfortunately, they also attack normal cells that rapidly divide. That means chemotherapy can have an effect on healthy cells as well as on cancer cells.
Not everyone will get the same drugs or receive them the same way. Your treatment will be individualized for you. Before treatment starts, you will meet with a medical oncologist. This is a doctor who specializes in treating cancer with drugs. The doctor will talk with you about your treatment and explain what you might expect. The actual treatment the doctor prescribes will be based on an evaluation of these factors:
The kind of cancer you have--whether it is colon or rectal cancer
The stage of the cancer
The goal of the treatment--for instance, to shrink a tumor before surgery or to relieve symptoms from an advanced cancer
Your general health
Concerns you have about side effects
What treatments you have had in the past (if any)
Your doctor will work with you on a plan for the appropriate drug or combination of drugs, as well as how you will receive the drugs and how long you should take them.
Most people have chemotherapy as an outpatient at a hospital or clinic, at the doctor's office, or at home. Sometimes, though, depending on the drugs and your health, you may need to stay in the hospital during treatment.
You may receive drugs by pill, by injection, or through a combination of the two. You usually receive them over a period of time. For instance, you may go to the hospital and receive drugs once a week for four weeks. Then you may have two weeks when you don't receive any drugs. At the end of the six weeks, the cycle starts over. If your doctor doesn't tell you, you should ask how long this pattern will last. Knowing when it will end can make the routine easier to stay with.
One common way people receive drugs for colorectal cancer is intravenously--as a bolus, as a longer IV infusion, or as a continuous infusion. A bolus (or IV push) is a dose of drug that's given intravenously (IV) all at once over a short period of time (usually a few minutes). An IV infusion can last from 30 minutes to a few hours. A continuous infusion is given continuously by an electric pump that you wear all day, usually for one to seven days. With this approach, the drug goes into your system more slowly, so you may be able to tolerate it better. That means you may have fewer side effects.
Here is a list of common drugs used for colorectal cancer:
Camptosar (irinotecan, CPT-11)
These drugs are often given along with targeted therapies.