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Introduction to Chemotherapy

Cancer is defined as the unrestrained growth of cells that destroy normal tissue and body parts.

The goal of chemotherapy is to inhibit the growth of cancer cells while causing as little effect on normal cells as possible.

Cancer is the number one natural cause of death in geriatric feline and canine patients; it accounts for nearly 50 percent of deaths each year

Families hearing the words cancer and/or chemotherapy will often visualize what they may have seen friends and family members go through. Their first thoughts are of vomiting, diarrhea, and of course hair loss. Side effects in our patients are normally not as severe, the reason in part is that we can adjust our treatment plan keeping in mind our primary concern in treating our patients is to ensure quality of life, not longevity.

A chemotherapy treatment plan is best left up to the oncologist or veterinarian with the most experience treating the specific cancer your patient has. There is often a primary chemotherapy drug which is known as having the best results for each type of cancer. We often start with this drug but always keep in mind each patient is an individual and we may have to alter our initial treatment plan. Quite often it is necessary and beneficial to combine drugs which will often enhance the activities of each other. Combining can also minimize their dose-limiting toxicities and help reduce the development of tumor resistance.

The treatment schedule will vary depending on the type of cancer and the chemotherapy drug chosen. In many cases once the initial treatment plan has been concluded the patient will require periodic follow up treatments for the rest of the patient’s life. For best therapeutic results we use a drug with a dose that causes minimal toxicity with maximal effectiveness. The most effective dose is often very close to the toxic dose.

Chemotherapy drugs can be life saving to our patients but dangerous to those who are handling and administrating the drugs. Only personnel who have been trained in administrating chemotherapy should be handling the drugs. Each drug will have a list of doses, route of administration, drug interactions, laboratory requirements, etc. As a technician it is a good idea to research each drug prior to handling it.

Side Effects

Most chemotherapy drugs have side effects, though the potential benefit is huge. Hair loss is not very common, though is more noticeable in breeds that grow hair continually such as Poodles. Cats will often lose all or most of their whiskers.

Gastrointestinal disorders are common 2-7 days after chemotherapy is administered. Because of this the DVM will normally prescribe medication to help prevent or treat GI disorders.

Reduction in WBC’s –Many chemotherapy drugs impair the bone marrow’s ability to produce cells. As a result neutropenia may occur 7-10 days after chemotherapy. The patient’s ability to fight off infection is impaired. Depending on the severity in reduction of WBC’s an antibiotic may need to be dispensed as well as a repeat of the blood work.

Tissue damage can be seen if the drug accidently goes extravascular. Severe damage can occur if not treated ASAP. Each drug will have its own protocol for treating the area.

Allergic reactions are rare and would occur during administration. Treat as an allergic anaphylaxis.

Safety Items

Safety measures must be taken during all phases of chemotherapy, preparing the drug, administering, disposal of the drug and waste material.

A luminal flow biological safety cabinet should be used when preparing chemotherapy drugs.

Chemotherapy drugs must be stored in an area away from all other medication. Items to be refrigerated must be placed in a Ziploc bag. Date and time the bag when the vial is opened. You must have a refrigerator just for chemotherapy drugs.

Pills should NOT be split, and gloves are to be worn when administering in the hospital or at home by the owner.

A pill counter for chemotherapy drugs ONLY should be used.

Chemotherapy gloves are to be worn while dispensing oral drugs.

Chemotherapy latex gloves, protective eyewear, a respirator-mask, and a disposable gown with closed-cuff sleeves should be worn by all members treating the patient.

During parental administration using a Luer-Lock syringe will decrease the risk of leakage.
Hydrophobic filters that insert into chemotherapy vials will prevent aerosolization of drugs during preparation.

Handling Waste Products
24-72 hours post chemotherapy administration the patient’s urine, stool, and vomit must be considered contaminated. Care must be taken during the clean up process and pregnant and nursing woman should avoid participating in the clean up process.

Pet owner and veterinary staff must wear exam gloves during clean up.
The patient should be encouraged to urinate in an area that will drain urine quickly. If that’s not possible pouring copious amounts of water, avoiding splashing, onto the urine will help dilute the urine. Stool and vomit should be double bagged and disposed of. If indoors, the area should be cleaned with a general disinfectant, again avoiding splashing of fluids.

Avoid pressurizing soiled cages and runs to avoid aerosolizing.

For further information on the step by step directions for administration of some injectable chemotherapy drugs, a checklist and a Chemotherapy Flow Chart for charting see our specialty folder.

References:
Oncology for Veterinary Technicians and Nurses – Moore and Frimberger
www.vetcancersociety.org