When can I recommend electrochemotherapy?

Electrochemotherapy is a treatment which we have been offering at NDSR for the last 4 years. It has become a very useful part of our armoury for both improving the quality of life in animals with non-resectable cancer and for preventing the recurrence of incompletely excised tumours.

When do we recommend it?

We use electrochemotherapy in two ways:

• Most commonly it is to try and prevent the recurrence of incompletely excised tumours. This includes mast cell tumours, soft tissue sarcomas, injection site sarcomas, but is not limited to these. There is evidence that the course of two treatments, given two weeks apart is successful at achieving this aim.
• We also use electrochemotherapy to control tumours for which removal is not possible or advised. Examples of cases we have successfully treated include glossal squamous cell carcinomas, malignant melanoma of the nose, large perianal adenomas, cutaneous plasmacytomas and mast cell tumours.

But what is electrochemotherapy?

Electrochemotherapy is the combination of electroporation – giving electric pulses across the area affected by the tumour- and chemotherapy, usually bleomycin given intravenously. The electroporation allows bleomycin to enter (and subsequently kill) the tumour cells. At the doses administered, we do not expect any systemic side effects.

The treatment is given with the patient anaesthetised. Electroporation doesn’t cause residual pain, but would be uncomfortable if administered to an awake patient. We administer electrochemotherapy on an outpatient basis.

Just as we do when administering chemotherapy, this treatment is administered at a dose which can control the tumour, but also aims to limit the side effects. Most cats and dogs who receive treatment to the site of an incompletely excised tumour do not experience any side effects. There is however a risk of causing local inflammation. We advise analgesia for 5 days and a Buster collar if needed.

When we successfully treat macroscopic tumours, there is expected to be necrosis and a period of healing for 1-2 weeks afterwards. Supportive care is provided as required.

How does electrochemotherapy compare to other options?

For some non-resectable tumours and for incompletely excised tumours, one of the main alternative treatment options is radiotherapy. When compared to radiotherapy, electrochemotherapy involves fewer treatments and is significantly less expensive, but there is also less evidence that it will be a successful treatment. So for dogs and cats where radiotherapy is not an option due to expense or concerns over repeated visits, electrochemotherapy can be a great alternative when compared with monitoring alone.

Case Example

Envelope is an unusually named and lovely dog who came to see us following incomplete excision of a high-grade soft tissue sarcoma.

Incompletely excised grade III soft tissue sarcomas are extremely likely to recur following surgery.

Envelope is a rescued dog and nervous in the vets. When we discussed treatment options, radiotherapy did not appear a good option to her owner given the number of visits required. When we examined the other options available to us, the only surgical option to prevent recurrence would be amputation and this would not be advised unless recurrence had already occurred. The other choice would be metronomic chemotherapy which is less likely to be successful and does have some risks and requirements for regular checks. Electrochemotherapy was therefore recommended as a good option.

A study of dogs with high grade soft tissue sarcomas treated with electrochemotherapy showed a recurrence rate of less than half of the reported rate without treatment.

Envelope came to see us for the second treatment and was admitted into the hospital at 10am. Upon examination, we found no evidence of side effects from her first treatment. She was then anaesthetised, and we marked out and clipped the treatment area surrounding the scar. We applied the electroporation, 5 minutes after injecting bleomycin.

Envelope was ready to go home by 2pm. Following her discharge from the hospital, we have advised ongoing checks every 3 months.

 

The probe and electrodes used to apply the electroporation in Envelope’s case

 

Thanks to Envelope’s owner for taking this photo!