Why and how is chemotherapy given?

Why is chemotherapy used?

  • To cure certain cancers
  • To kill any microscopic cancer cells that might be present but unseen in lymph nodes
  • To shrink tumors before surgery or radiation
  • To control the growth of tumor cells when a cure is not a possibility
  • To relieve pain by shrinking a tumor pressing on a nerve(s)

How can cancer drugs be given?

How chemotherapy is given depends on the drug itself and various factors concerning the patient.

  • By mouth
  • In the vein (IV)*
  • In an artery (intra-arterial)
  • Into a muscle
  • Into the tissue just under the skin (subcutaneous)
  • Directly into a body cavity, such as the bladder or abdomen (peritoneum)
  • Directly into an organ, such as the liver or a limb.
  • Into the cerebrospinal fluid (this is the fluid that surrounds our spinal cord and brain)

*When many needle sticks into a vein are expected, some patients will have a port surgically placed just under the skin in the upper chest. This port gives health care workers easy access to a vein to give medicines or to have blood specimens drawn.

What is a chemotherapy regimen and cycle?

A chemotherapy regimen is usually given in cycles. A regimen is the specific combination of chemotherapy medicines you will receive at this stage of treatment and the number of cycles you will receive it. Your regimen may change over time as the doctors and nurses see how your body reacts to the different medicines. Some patients may have to adjust their regimen several times before they find one that works best for them.

The other term often used when talking about chemotherapy is cycle. A cycle of chemotherapy is repeating the way a drug or a group of drugs is given over a specific number of days. For example, one cycle may be taking the drug for every day the first week and then taking the next week off. The cycle is repeated a specific number of times. The doctor chooses the drugs and the number of cycles of chemotherapy from completed and successful research studies, which spell out the dose of the drugs to be given and how often they should be given. Sometimes the timing or dose of a chemo drug will have to be changed because of the way your body is responding to the drugs.

For example, a patient may receive Drug A and Drug B as their treatment. A cycle may consist of coming to the hospital to receive the chemotherapy drugs through an IV every day for two weeks and then taking two weeks off. Their regimen may be to go through three cycles of that drug combination, over a period of 12 weeks.

Last reviewed: 
October 2016

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