jovan vitanovski/Shutterstock

Most cancers cannot be cured and scientists should give up trying and, instead, look for ways to manage the disease, the director of the Centre for Cancer and Evolution at The Institute of Cancer Research, has claimed.

Professor Mel Greaves, an expert in childhood leukaemia, said developing more advanced cures would only lead to cancer cells becoming more resistant to treatment.

He believes that scientists should focus on prevention, such as giving aspirin to all over 50s to stop the onset of stomach cancer, and stalling the disease once it has emerged.

"With a lot of respect to oncologists we need to get smarter," he told journalists at a press briefing in London yesterday.

"Very intelligent people who aren't scientifically minded think there must be a cause, there must be a cure and it's just not right. It's fundamentally wrong.

"Talking about a cure in terms of elimination is just not very realistic. There are some examples of it. Childhood leukaemia had a cure rate now of 90 per cent but that is an exception.

"There are a few cancers that are curable but most are probably not including the common carcinomas in adults.

"We should be a bit more subtle. We should not try to eliminate the cancer, we should try to hold it in check."

Many institutions are attempting to find cures for individual cancers using increasingly advanced methods.

They include ramping up the body's own immune system to fight the disease; personalised treatments based on the DNA of the tumours and gene therapies.

But Prof Greaves believes no therapy will work in the long term because tumours continue to evolve like all life-forms. He is a leading figure in the study of cancer evolution – the Darwinian process by which cancer cells mutate and diversify by natural selection within our tissue ecosystems

"You must have noticed that when you read reports about new target therapies, isn't it odd that they work dramatically, but three months later (cancer) is back with a bang. It's almost always the story.

"I would argue that if you look at the age distribution of cancers, most people are in the 60s, 70s and 80s. If you could slow everything down for 10 to 15 years, maybe 20, then that would be a huge advance.

"It is wrong to think we need some fancy therapy that kills it. I think slowing it down is a much more interesting proposition. "

However, leading cancer expert Professor Karol Sikora, Dean of Medicine at the University of Buckingham, said he was confident cures could still be found.

"I think this is a pessimistic view, and strange given that Professor Greaves has done so much to help find a cure for leukaemia.

"I absolutely think we will find new cures in the future and the closer we get to understanding the mechanism of the disease, the quicker this will happen."

There are more than 200 types of cancer and more than 330,000 people are diagnosed each year. More than one in three people will develop some form of cancer in their lifetime.

Breast, lung, prostate and bowl account for more than half of all new cancers each year and more than a third of cancers are diagnosed in people over the age of 75.

Half of people now survive cancer for at least 10 years and survival rates have doubled in the UK in the last 40 years. But it still causes more than one in four of all deaths.

Prof Greaves said that preventing cancer should be of primary importance, using drugs which tackle the 'ecosystem' of the disease – by changing the chemical make-up of the body.

"I think one of the best drugs that exists is aspirin. It's fantastic what it does. There is a big debate about whether we should all take aspirin over a certain age. I think over 50 we probably should, because it has a huge impact on gastro-intestinal cancers.

"Here is another drug that doesn't attempt to kill the cancer; it simply tries to restrain it."

However Professor Peter Johnson, chief clinician at Cancer Research UK said many people had already seen their cancers cured.

"We already have cures for many types of cancer. For example, millions of people who have had breast cancer, prostate cancer or bowel cancer are alive years after their surgery to remove the tumour, if it was caught early enough," he said.

"However, when people talk about a cure for cancer they usually mean drugs, and here things are more complicated. Cancer isn't just one disease – there are hundreds of types, and as we understand the genetic signatures of individual tumours it's becoming clear that each person's cancer is as unique as they are – so it's simplistic to talk about a single cure. "