Surrey-based North Downs Specialist Referrals reports that it has had 'extraordinary' results using electrochemotherapy, a form of targeted chemotherapy, after it eradicated all traces of disease in its first tranche of eight patients since the start of last November.

In one case, Tigga, a 17-year-old cat with an itchy and destructive tumour on her nose, was in complete remission within 44 days. In another case, a tumour vanished in a dog where the aim of the treatment was only to shrink the mass before an operation to remove it.

NDSR, which is based in Bletchingley, is the only referral centre in the UK and one of very few in the world offering electrochemotherapy in pets.

Electrochemotherapy is given in two stages.

First, the patient is given a mild dose of intravenous chemotherapy in the normal way and then, using a probe, a precise electrical charge is given to the area on or around the tumour.

This temporarily opens up tiny holes in the cells, big enough to allow the drug to enter, which then close again in microseconds. This means the drug will only attack cancerous cells, unlike normal chemotherapy, which also kills healthy cells. 

Gerry Polton, clinical director of oncology at NDSR, said: "Normal chemotherapy works on the principle of being more damaging to cancer than non-cancerous tissue. Some cancers are more resilient, so there are differences in how they respond to treatment, and this can cause more harm to the patient. 

"Electrochemotherapy involves clever anatomical targeting of a specific site and is an effective way of protecting healthy cells.

"The results we are seeing in cases like Tigga’s are unprecedented and we are learning about the procedure all the time. We are always looking for better ways of treating cancer without the effect of harming the patient indiscriminately and this has proved to be a very effective way of doing this."

According to NDSR, the results could help inform the development of the targeted treatment in humans, where electrochemotherapy is used in a small number of cases in the NHS.

At present, many clinical trials are carried out on laboratory animals which are bred with no immune system – but dogs have similarities in genetics to humans and have working immune systems, meaning they can provide a more accurate parallel for how the treatment may work in people.

Gerry said: "A pet dog would be a good model for human cancer studies. It's a mammal with a heartbeat, blood supply and working immune system.

"Progress with electrochemotherapy in animals is being made in parallel with progress in electrochemotherapy in the human field, and what we are learning may even inform what is happening in people.

"Electrochemotherapy is a form of treatment which Cancer Research UK describe as 'fairly new' on its website, with limited information about its effectiveness. So maybe something would be gained from learning together."

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