When he first started suffering from sharp pains in the summer of 2009 – usually when he was having a pint with friends after work, or after a round of golf – he assumed it was heartburn. Antacids made no difference. his GP thought it might be an ulcer; tablets did not help. Blood tests found diabetes, for which he was treated, yet still the pains continued. Mr Jones began to worry.

“I started to do some research on the internet, and I wondered if it might be pancreatitis, an inflammation that could explain the diabetes, because the pancreas produces insulin. I went back to my GP and asked to be referred to a specialist in pancreatic disease.”

Scans detected some kind of mass in the organ. It could be scar tissue, or a benign lump, the businessman was told. two weeks before Christmas he received the results of a biopsy. It was cancer, it was advanced, and it was inoperable. the expected prognosis was 12 to 14 months.

“I was only 43, my son was then not yet 15, and he has special needs,” says Mr Jones. “The idea that I could be gone in a year, that I would leave him was just not something I could accept. Everyone in my family was crying, but I felt totally numb.”

In fact, he says, he never accepted the prognosis. “I never thought this might be my last Christmas. I couldn’t let myself think that. I thought, well that’s the average, I might get more. I decided whatever they said, I would settle for three years. that would mean my boy had finished school; it was enough time to sort out my business and my will. Three years would do.”

Searching online, he read about experimental trials for patients with pancreatic cancer. “When you’ve got nothing to get hold of, when you have nowhere to go, you grab at anything,” says Mr Jones. He asked his specialist at Poole Hospital if there were any such trials in which he could take part. within weeks, he had signed up for one of the most ground-breaking pieces of medical research of recent decades.

Five years ago, a group of scientists embarked on a radical trial. In recent years, most of the advances in treatment of pancreatic cancer had involved improved targeting of radiation, to deliver the burning rays most precisely to the cancer, and to limit damage to the tissue around it. but at the same time, scientists were increasingly aware of the role of genes in making some cancers more resistant to radiation than others.

The question was, could anything be done to switch off some of the molecular reactions that occur with cancer, and to make tumours more sensitive to radiation, so that they shrunk sufficiently that they could be removed. the group of scientists, now based at the Gray Institute for Radiation Oncology and Biology, in Oxford, decided to see whether a drug called Nelfinavir, used for the treatment of HIV, could change the way tumours responded to radiation.

Twelve patients with inoperable tumours were enrolled on a phase I trial, used to establish the safety and toxicity of a drug. they were given daily doses of the drug before radiation therapy. At the end of the trial, led by Dr Thomas Brunner, the patients were scanned again.

The research team was stunned by the results. of 10 patients who completed the course, six were able to have previously inoperable tumours removed. across the group, overall average survival time more than doubled. More remarkably still, in one case the combination of drug treatment and radiotherapy had eradicated every living cancer cell, with no trace of disease found by surgeons.

“There was a complete pathological response. No sign of the cancer at all. It had completely disappeared.”

The excitement from Professor Gillies McKenna, the head of the Gray Institute, is palpable. He quickly checks himself. forty years pioneering advances in cancer treatment make him all too aware of the desperation of those diagnosed with advanced disease, and the rush to pin “miracle” labels on significant, but faltering, steps.

Yet four years since the trial started, the man remains free of cancer. a female patient, who had 90 per cent of cancer cells destroyed, also remains healthy, more than three years on.

“We are really excited about this,” says Prof McKenna. “We are still several years away from proving that this is a major breakthrough, because this was a small trial. but to get these kinds of results for pancreatic cancer – well, we just couldn’t help but prick up our ears.”

Early this year, the team embarked on a larger phase II trial. Kevin Jones is among 80 patients being recruited to try the experimental technique. He began treatment in March.

“They never gave any false promises,” says Mr Jones. “It had taken years of research to get to this point, and the results they had were on a small group. Why would there be a major breakthrough now? well, the way I saw it, why not?”

For two weeks, he took a daily dose of the HIV drug. for six more weeks, he underwent daily radiation treatment at Oxford’s Churchill Hospital. Regular measurements of tumour markers, which reflect the extent of disease, showed dramatic improvements. but by the end of the treatment, he felt terrible.

“I felt really sick, I couldn’t eat and I didn’t have much strength. I decided to take a holiday with my son in case it was the last one we had,” says Mr Jones.

He took his son Brett, who has Asperger’s syndrome, to Canada, where they had been building a holiday home. “It was a special time, bonding, building this home together. Whatever else happened, I was grateful for that time.”

He returned to England to undergo further scans. In June, the research team asked him to come for a consultation with one of the hospital’s surgeons. “They showed me the scan. Where there had previously been a solid mass of two-and-a-half inches, there was now a faint outline, with a hole in the middle.”

The research team and surgeons were cautious, warning him it was impossible to say from seeing the scans whether any of the tissues were cancerous. Nevertheless, says Mr Jones: “I walked out of that room feeling 10ft tall.”

In July, he underwent surgery to remove the mass. It was then that surgeons told him that not a single cancer cell had been found; every deadly tissue had been destroyed. He was now the second such case to emerge from the Oxford trials.

“They couldn’t believe it. the surgeon who operated said he had never seen anything like it,” says Mr Jones.

In such unchartered territory, no one can predict whether his cancer will return.

He says: “The surgeons said to me, ‘Don’t think in terms of three years, or five years, you might have two decades – you might have more.’ This time last year I’d have settled for three years. Now I might be cured.”

The centre is still recruiting patients for the current trial, which will run for two years. Scientists like Prof McKenna, who returned to Britain to set up the institute, after 40 years leading radiation therapy programmes across the US, believe the evidence emerging may be “the tip of an iceberg” – giving scientists valuable lessons about ways to both block the progress of many aggressive cancers, and to enable different types of tumours to respond better to treatment.

But medical breakthroughs are expensive. the institute, set up just two years ago, receives most of its funding from Cancer Research UK, which is funded by donations from the public. Prof McKenna has had to fight hard to ensure funding for research into treatments, such as radiation therapy, which can be neglected.

“People dismiss radiotherapy as somehow being old-fashioned, as something that would die out when new treatments were being invented,” he says. “Actually, that prediction was almost 100 per cent wrong; some of the most dramatic improvements in cancer over the past decade have come from this field.

“Our teams are here and we are ready to go to work, but we are totally dependent on the generosity of the public to make the breakthroughs we need.”

 to find out about trials for advanced pancreatic cancer: rob.ox.ac.uk