Methods for Administering Chemotherapy

Chemotherapy can be administered eternally (through the gastrointestinal tract) or parenterally – through some other means.  When most people picture chemotherapy, they picture intravenous delivery and indeed, most cytotoxic therapy is given intravenously.  But there are other methods.

Enteral methods

Most non-chemo drugs are taken orally – by pill or solution. Some chemotherapy agents are available in liquid, tablet or capsule form – the newer “targeted” therapy among them as well as hormone therapy given as an adjuvant.  While patients usually prefer oral ingestion to intravenous administration, most traditional chemo agents cannot be swallowed because they would be denatured in the stomach and rendered inactive.

An advantage of oral administration is that it involves no needles (and most people find needles unpleasant). Another benefit is that patients can take the medicine at home. A disadvantage is that the medicine may irritate the digestive system.   Other disadvantages that may occur in oral chemotherapy are side effects including nausea, vomiting, diarrhea, mouth sore, hair loss and low white blood cell counts, although these side effects happen with other methods of administering chemotherapy, too.

Aside from oral (by mouth), enteral methods include gastric (direct injection to the stomach) and rectal.  Gastric administration can be through a nasogastric tube through the nose and down the esophogus to the stomach.  The similar orogastric tube goes through the mouth.  Another method of gastric administration is the percutaneous endoscopic gastrostomy tube.  Rectal administration involves getting the drug into a solid form – or absorbed into or onto a solid item – and inserting the solid as a suppository.

Parenteral Methods

Paracentral administration – paracentraol means any method that is not eternal but usually does not include regional application methods -is usually administration of the drug to a vein (intraveneous) or an artery (intra-arterial).

Peripheral Intravenous Chemotherapy

An intravenous (IV) tube is inserted via needle into a blood vessel in the hand or arm in this method of chemotherapy. The medicine (or medicines) goes straight into the circulatory system through a vein. One advantage of this type of treatment is that the medicine enters the body quickly. Peripheral intravenous chemotherapy can also be administered in the home with the proper set-up and a visiting nurse. Disadvantages can include extravasation which is when the medicineiv administation leaks out of the vein which, in turn, causes the skin to burn and blister. IV infiltration is when fluid infuses into the tissue near the entry point to the skin. It is an incorrect method of administration, but happens fairly often by accident.  It is also uncomfortable to insert the needle and the whole process is scary for some patients, at least when they start.

The drug is dissolved or otherwise suspended in an aqueous solution.  Depending on the regimen, the drug may be injected in a matter of seconds or slowly infused over the course of hours.

The most common intravenous administration is through a temporary catheter inserted into the hand or the arm.  It might take less than a minute to deliver the bolus to the patient or it might take hours – there are many regimens.  A peripherally inserted central catheter is a more permanent device for patients on a course of chemo that may last up to several weeks.

Topical Chemotherapy

Anticancer drugs are applied to the skin as a lotion, cream or ointment. The advantages are that it is easy (the patient can apply medicine), quick and can be done at home. Disadvantages can include sensitive and red skin and skin that burns, discharges fluid, itches and changes color.

Intramuscular Chemotherapy

The chemotherapy is injected into a muscle in the arm, thigh or buttock. Although the shot may hurt for a bit, this is a quick way to administer chemo medicine. This type of chemotherapy can be given in the home by a healthcare professional.

Subcutaneous Chemotherapy

This type of treatment, also known as sub-q, uses a small needle that is similar to ones used by diabetics for administering insulin. Subcutaneous injections involve needle delivery of the drug under the skin but not directly into a blood vessel.   An advantage to this method is that the chemotherapy medicine enters the circulatory system at a slower rate; therefore, the chances of systemic toxicity are lowered. Disadvantages can include irritation, damage to muscles, and damage to skin tissue.  Intramuscular injections go deeper – though the skin – but they likewise do not enter a blood vessel directly.  These delivery methods are not often used for classical chemotherapy drugs

Intra-arterial Chemotherapy

Medicine is injected straight into an artery (through a catheter), usually to treat a single area. (See page on regional chemotherapy.)  The catheter is placed directly into the artery that feeds the tumor. Because the chemotherapy agent is directed only to a specific area, the side effects of the drug are limited in other parts of the body. When used in brain cancer treatment, this method requires brain scans, arteriograms, anesthesia, seizure drugs and blood thinners. There is potential for hemorrhage or stroke following the procedure.

Regional Variations

Intrapleural and intraperitoneal administration involves delivering chemotherapy directly to cavities in the body that are afflicted with cancers such as mesothelioma and ovarian cancer.  Intravesicular administration involves delivering medicine to the bladder via a urinary catheter.  These forms of regional administration make up a minority of cases of chemotherapy.

Catheters

Today’s catheters are flexible plastic (often transparent) tubes that are employed to deliver drugs to a vein for intravenous treatment.  There are many regimens for drug therapy, so the peripheral catheters may stay in for a few minutes or even up to several days.

Old catheters are not re-used by other patients; they are disposed of as medical waste.

The most common site of injection is the hand or lower arm, but sometimes the point of insertion is the upper arm or neck.  Central venous access devices (CVADs) are more often inserted at the neck or chest.  Unlike peripheral catheters, the CVAD is closer to the central circulatory system, often being placed near a jugular vein.  The catheters can be thicker in this set up and double- and triple-lumen catheters can be employed.  Lumens are the channels through the catheter.  The multi-lumen catheter allows better control of pressure, parenternal nutrition, drug delivery, and taking samples of blood.

Anti-nausea medication can also be delivered by IV.

CVADs can remain in place for months.  Depending on the type and stage of cancer and the medical team’s approach, some patients may need to be on chemotherapy for an extended period and ports can make their lives easier.

Implantable ports, also called port-a-caths, are plastic or metal disks implanted beneath the skin.  They offer quicker and easier access to the interior of the body for frequent application of treatment.  They reduce the number of times a nurse has to prick the skin (reducing bruising) and facilitate home administration of chemotherapy.  Ports can come with two or three openings for infusion of more than one medication at a time.

Port have caps which should be on them when they are not in use.  Even so, there is the possibility for infection.  The nursing team instructs the patient about care, including avoiding touching the port when the cap is removed, washing hands before even touching the cap, and not swimming.  Blood clots are also a problem so catheters used in ports are often flushed with an anticoagulant (blood thinner) solution.  Saline solution is also used to clean catheters,

Other Forms of Chemotherapy Administration

Intralesion or Intratumoral – medicine is injected right into the tumor.

Metronomic Chemotherapy – continuous low doses

Dose-dense Chemotherapy – a regimen in which the time between administrations of drugs is shortened.

Does it hurt?  – Pain of injection is minimal most of the time.  Sometimes there is a burning when the medicine courses through the blood vessels.

Where does it take place? – Many medical facilities are employed for administration of chemotherapy.  Simple doctors’ offices, special chemotherapy clinics, and hospitals are common places.

Once the Drug is in the Body

The therapeutic window refers to the dosage that doctors administer in an attempt to make the treatment both safe and effective.  Too low a dose is not effective in treating the disease.  Too high a dose and the side effects of the drug become detrimental or dangerous.  One challenge with chemotherapy is that the therapeutic windows tend to be narrow.  The toxic dose isn’t too much higher than the effective dose.  More on dosing.

One advantage of targeted therapies is that the therapeutic window may be wider.

See page on pharmacokinetics.

Scheduling

When and how often to administer chemotherapy is a whole field unto itself.  Some methods are dose-dense, metronomic, and variable.