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Cancer cure? The abscopal effect

On very rare occasions, radiotherapy on one cancer tumour can trigger the immune system to recognise and kill multiple tumours throughout the body. Dr Karl introduces the mysterious 'abscopal effect'.

A little while ago I came down with laryngitis. I wasn't worried in the slightest — although I did lie about with the 'vapours' for days! I knew what would happen. My immune system would recognise the bad guys that invaded my larynx — and then kill them. Over a period of about a week I got worse, and then I got completely better — just as I expected.

So why is cancer such a killer? Why doesn't your immune system recognise the cancer as the 'bad guy' — and kill it? The answer is that the cancer seems to be able to hide from, or trick, your immune system.

But every now and then — and let me emphasise that this is so rare that it falls into the category of the genuine medical curiosity — every now and then the immune system can recognise and kill an established widespread cancer.

Welcome to the 'abscopal effect'.

But first, let me also emphasise that there is no single disease called 'cancer'. Instead, there are several hundred different types of cancers — each with their own cause, pathology, natural history, treatment and so on. For example, most men will get cancer of the prostate. But it won't kill them, and they'll die with that cancer, not because of it. On the other hand, cancer of the stomach will kill 90 per cent of sufferers within five years.

And of course, there is another layer of complexity. For example, there are at least four different types of lung cancer, each with their own cause, cell type, aggressiveness, etc.

Now that you know that, let's dive into the abscopal effect. 'Ab' means 'away', while 'scopal' refers to a 'target'. So abscopal effect in this case means that you treat a cancer in one part of the body, and somehow, all of that cancer which is spread anywhere else in the whole body is killed.

I first read about this in Discover Magazine — their March 2014 issue. Daniel, a healthy fit man in his mid-30s was diagnosed with malignant melanoma — a particularly aggressive version of skin cancer. Even though his single original black mole was surgically removed, within two months it had spread to his lymph nodes, and within a year had sprouted secondary cancers in his lungs and liver. He couldn't play basketball any more, lost about 15 kilograms, needed a cane just to be able to walk and just recently had begun to suffer severe pain in his right hip. Unfortunately, this meant that secondary cancers were now spreading into his bones. In fact, the one inside his right hip was so far advanced that it was causing major effects on the bone, and hence, the severe pain. Daniel's outlook was grim — with probably only a few months of life left.

The consulting doctor decided to treat the hip pain with a high dose of radiation. His hope was that it would ease Daniel's hip pain. He expected the radiation to slow down the growth of the secondary cancer in the hip, or even kill some of it. This would relieve the pain. The doctor couldn't give such a high dose of radiation to all the many secondary cancers throughout Daniel's body, because it would kill him. The doctor booked Daniel a three-month follow-up appointment, not really expecting him to be well enough to actually come in — or even be alive.

Three months later, Daniel returned — weighing five kilograms more, looking healthier, and free of pain. Daniel insisted on having a CT scan. Amazingly, the many, many secondary cancers throughout his body (lymph nodes, bone, lungs, liver and so on) had vanished — leaving behind only tiny scars where once the cancers had been.

When Daniel returned another three months later, he was a different person. Not only had he regained a few more kilograms of solid muscle, he could now play basketball again, and was back at work. Fourteen years later, Daniel's malignant melanoma had still not returned. (I hope it doesn't return — for Daniel's sake).

Now you might have heard of cases where a cancer will undergo 'spontaneous regression'. The five most common cancers where this very rare phenomenon happens are renal cell carcinoma, lymphoma and leukaemia, neuroblastoma, carcinoma of the breast, and malignant melanoma (which is what Daniel had).

Perhaps the abscopal effect works in a similar way to spontaneous regression — and perhaps not.

Let me emphasise very strongly that the abscopal effect is very, very, very uncommon. Don't expect it to be clinically available or promoted as a treatment option any time in the near future.

It does seem that the abscopal effect is intimately involved and intertwined with the immune system — which is fiendishly complicated.

At the moment, our understanding of the immune system is still very shallow and primitive. But we have a few strong leads and a couple of wild guesses. So I'll talk more about them, next time ...

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