Veterinary Oncology: Electrochemotherapy
The oncology service at Oakland Veterinary Referral Services offers an advanced treatment option for cancer patients called electrochemotherapy (ECT). ECT involves combining a normally poorly absorbed chemotherapy agent with delivery of an electrical field (electroporation) to the tumor bed or surgical scar. Electroporation allows the pores within cells to become temporarily enlarged, increasing the drug concentration into the affected area by up to one thousand fold.
Questions About Electrochemotherapy
- How is ECT given?
Patients are dropped off in the morning fasted (no food or water after midnight) and will go home that same day (outpatient procedure). Blood testing will be performed prior to anesthesia. Your pet will be anesthetized with a short-acting anesthetic. The chemotherapy drug will be given IV or intratumoral, determined on a case-by-case basis. The concentration of drug used is lower compared to standard chemotherapy, allowing much less toxicity. Five to ten minutes following chemotherapy administration, very brief electrical pulses are delivered to the tumor or surgical scar. The electrical pulses cause only the cells directly around the electrode to become permeable, and only these cells absorb any significant quantity of chemotherapy.
- What are the side effects?
Due to the low dose of chemotherapy, systemic side effects are low (vomiting, nausea, depression). If these occur, they may be due to anesthesia; we can consider other anesthetic protocols or administer medications to help prevent nausea.
Typical side effects are limited to the tumor site itself and can include local reactions such as inflammation, redness, itchiness and discomfort. These side effects are temporary and peak about 1-3 days post-treatment and are managed with pain medications, anti-inflammatories and cold-packing the site for 1-7 days post-treatment.
Pets with bulky tumors that have a good response to ECT may experience tumor necrosis (cells dying within the tumor) and can be at higher risk for infection. Antibiotics may be recommended.
- How safe is this treatment?
Chemotherapy doses are lowered decreasing risk of side effects. Risk with anesthesia is generally low, but risk is a case-by-case basis depending upon other pre-existing medical problems. This procedure is considered safe.
- What tumors can be treated with ECT?
Your veterinary oncologist will determine if ECT is an appropriate treatment for your pet. The following tumors have been treated with ECT:
- Tumors of the mouth (melanoma, epulides, squamous cell carcinoma, fibrosarcoma)
- Nasal planum tumors
- Soft tissue sarcoma (to treat certain inoperable tumors or residual disease following incomplete surgical removal)
- Mast cell tumors (to treat certain inoperable tumors or residual disease following incomplete surgical removal)
- Tumors around the anus or rectum
- Carcinoma of the skin
- Epitheliotropic lymphoma limited to one area of skin
- Mammary tumors
- How many treatments will my pet need?
For many pets in which ECT is recommended for incompletely removed tumors (soft tissue sarcoma or mast cell tumors), two treatments are given two weeks apart. For pets with visible tumors to which ECT is given, the number of treatments is dependent upon tumor size and response to treatment, but generally at least three are required to assess response.
- How soon can ECT be given to my pet post-surgery?
Some pets may be given their first treatment the same day of surgery. If ECT is given the same day of surgery, staples should not be placed to close the wound. There is concern of possible increased risk with wound dehiscence when ECT is given on the same day of surgery.
- Can my pet receive additional ECT if the tumor returns?
Yes, ECT can be given again in pets that have previously had a good response to treatment. Additional treatment options, such as surgery or radiation, may be recommended by your oncologist.
- Can ECT be given post-radiation?
Yes, however there is a higher risk for development of radiation recall. Radiation recall is an acute inflammatory reaction confined to previously irradiated areas that can be triggered when chemotherapy agents are administered after radiotherapy. It remains a poorly understood phenomenon, but increased awareness may aid early diagnosis and appropriate management.