How is chemotherapy given?

Author:  Gesche Tallen, MD, PhD, Editor:  Maria Yiallouros, Reviewer:  Prof. Dr. med. Dr. h.c. Günter Henze, English Translation:  Hannah McRae, Last modification:  2015/05/11

For a successful cancer treatment, a careful balance between killing the cancer cells and not damaging the healthy cells needs to be kept. This balance is mainly dependent on the dosage and administration route of the cytostatic agent as well as on when and how often it is given.

The following routes of administration for chemotherapy and corresponding abbreviations are commonly used by the caregiver team:

PO – “per os” (Latin) means “orally” or “by mouth”. The drug can be taken as a tablet, capsule, or juice, and is absorbed through the oral, gastric, and intestinal mucosa into the blood. The medication travels throughout the bloodstream and is carried to organs that process it further so that it can exert its effects on the cancer. Not every medication may reach the bloodstream through the digestive tract, thereby requiring other routes of administration.

IV – “intravenous” means “into the vein”. The medication is given directly into a vein by using a syringe or an indwelling venous catheter (central venous catheter). For some drugs, this is the only feasible route owing to their chemical structure. Also, drugs given intravenously can be expected to have a faster effect. Intravenous administration may be performed as a rapid injection called “bolus” or as a short- or long-term infusion.

SC – “subcutaneous” means “under the skin”. The medication is injected with a thin cannula (needle) under the skin from where it distributes.

IM – “intramuscular” means “into the muscle”. The medication is injected with a fine needle into a muscle (for example, into a muscle in the thigh).

I.Th – “intrathecal” means “into the cerebrospinal fluid (CSF)”. The drug is injected via a lumbar puncture into the CSF to reach the central nervous system (CNS).

I.Ven – “intraventricular” means “into the ventricle” (of the brain). The drug is administered through a Rickham or Ommaya reservoir into one of the side ventricles, from where it distributes into the central nervous system (CNS).

Long-term infusions serve to continuously provide the organism with a specific medication, such as a cytostatic drug or a certain fluid. A tumour, for example, may thus be exposed to a certain constant level of cytostatics for a longer period of time. In contrast, short-term intravenous or oral administrations, with the drug given at certain intervals, result in varying drug concentrations in the body, enabling the doctors to control the effects and side effects of the treatment in a different way.

Taken together, different administration routes result in different cumulative doses of a medication in the body. Choosing a feasible route of administration based on the type of disease and the drug's mechanism of action helps controlling the side effects of chemotherapy. Therefore, and based on the individual clinical situation of the patient, different types of cytostatic agents are used for treating different types of cancer with different dosages and routes of administration.